The McMinnville Photos
by Bruce Maccabee (c) 2000 by Bruce Maccabee
(Referred to as CUFOS Paper #2)

Original link at:

NOTE: The main text of this paper was started in 1977 and completed in 1981 and then submitted to the Center for UFO Studies (CUFOS) for presentation at the Second CUFOS UFO Symposium. The intent of this paper was to supplement the previous paper on the Trent photos, "On the Possibility that the McMinnville Photos Show A Distant Unidentifed Object," published by CUFOS in the Proceedings of the 1976 CUFOS Symposium. For various reasons this and the other papers presented at the Second CUFOS Symposium were not published until 1989 in the "Spectrum of UFO Research." Therefore, the previously published version includes the Addendum (1984) which provided further information on the analysis and further testimony regarding the Trents. Some modifications, clarifications and additions to the original text have been made in April and May, 2000 and are designated by "(NOTE 2000:....)" . An Addendum (2000) has also been added to bring the status of the Trent case up to date (as of my own site visit to the "remains" of the Trent farm, May 11, 2000!) 

On June 8, 1950 the local newspaper in McMinnville, Oregon (USA) published two photos of a "flying saucer" which had been taken by a farmer, Mr. Paul Trent. There was also a brief description of the sighting of the object by the farmer and his wife. Copies of the photos are presented in Figures 1 and 2. (NOTE 2000: see the photos associated with the previous paper.) Several other newspapers published reports of the Trent sighting based upon independent interviews and an International News Service (INS) newswire story about the sighting. The INS also obtained the original negatives, which were never returned to the Trents (nor did INS pay for the photos). The Trent photos subsequently appeared in many UFO books and articles. (NOTE 2000: as of the year 2000 the Trent photos have been published hundreds of times in newspapers, journals and books worldwide.) They achieved a unique measure of official recognition in 1968-1969 when the "Condon Report" (1) was published. In the report of that Air-Force funded study at the University of Colorado the photoanalyst, Dr. William Hartmann, stated that the photographic and verbal evidence in the Trent case was essentally consistent with the claim of the witnesses that " extraordinary flying object... tens of meters in diameter and evidently artificial, flew within the sight of two witnesses." Despite this strong endorsement, Hartmann admitted that a hoax could not be positively ruled out. (NOTE 2000: this was the first scientific analysis of this sighting even though the photos had been available for study for 17 years as 1967.) Several years later an investigation by Philip J. Klass and Robert Sheaffer (2) argued that the photographic evidence used by Hartmann (1) was not conclusive and that, furthermore, there seemed to be some discrepancies between the photographic evidence and the witness' story. Moreover, the stories published in the newspaper accounts seemed to be inconsistent with what Klass would have expected if the story had been true, leading Klass to indicate that the photos were probably a hoax. After seeing the analysis of Klass and Sheaffer, Hartmann revised his opinion: "I think Sheaffer's work removes the McMinnville case from consideration as evidence for the existence of disk like artificial aircraft...(and it) proves once again how difficult it is for any one solve all the cases. Perhaps no one has the experience for that because there are too many phenomena and methods for hoaxing."(2) My subsequent investigation (3, 4) of the original negatives confirmed Hartmann's original conclusion about the excessive brightness of the bottom of the image of the Unidentified Object (UO) and eliminated the claim (2) that there was a relatively long time lapse between the photos. Dr. Robert Nathan, at the Jet Propulsion Laboratory in Pasedena, CA (NOTE 2000: now retired), also searched for, and failed to find, indications of a suspending thread. (NOTE 2000: in recent years the original negatives have also been studied by interested persons at the Los Alamos National Laboratory in New Mexico and also at the Brooks Institute of Photography in Santa Barbara, CA. 

None of these independent investigations has turned up evidence of a hoax.) At the same time I was carefully studying the original negatives and improving upon the photometric analysis of Hartmann and Sheaffer (between January 1974 and November, 1977, when the first version of this paper was written), I carried out an intensive investigation into the background of the sighting and into the subsequent developments . (NOTE 2000: I continued the investigation into the early 1980s and again in the late 1990's, long after the original version of this paper was presented at the 1981 CUFOS conference. Pertinent results of those investigations are included in this presentation.) I have concluded, from communications with many people who have talked to the Trents, that no one who has met them personally would believe that they would think of creating any hoax or perpetrating a hoax as successful and long lasting as their flying saucer report. Dr. Hartmann, who interviewed them in 1967, was convinced of their veracity (1). However, as mentioned above, he later changed his mind (2,6) after reading Sheaffer's analysis (7). I have further concluded, contrary to the opinions expressed in Reference 2, that it cannot be proven from either verbal or photographic evidence that the case was a hoax. Instead, the available verbal and photographic evidence indicates that the sighting was not a hoax. (NOTE 2000: Evelyn died in 1997 and Paul in 1998. They were last interviewed in 1995 by Terry Halstead for a video documentary. They repeated their story once again and avowed that it was the truth.) 

The "classical" date, as reported in the initial newspaper stories (8,9,10) is May 11, 1950, which was a Thursday. That date is accepted here despite the seeming contradiction between the weather reported in a newspaper story (sky overcast at 5000 ft (10) ) and the McMinnville Airport weather report (mostly clear sky (11) ) or a sky that is uniformly overcast. (NOTE 2000: although the only source for the date is the Trent's themselves, there is nothing to contradict their claim.) 

The initial newspaper reports placed the time at 7:45 PM (8,9) or 7:30 PM (10) local standard time. Mrs. Trent has repeatedly claimed to me that the sun had not yet gone down when the photos were taken (12). According to the Salem, Oregon Airport Weather Report (13), the sunset was about 7:30 PM (rather than 7:15 as reported by Hartmann(1) ). A visible sunset would be consistent with the nearly clear sky reported for the evening of May 11. (NOTE 2000: there are hills to the west of the Trent farm. Hence the exact time when the sun would be below the local horizon could be different from the time of "official sunset.") Klass and Sheaffer (2, 14) have pointed to the rather sharp-appearing shadows of the ends of the roof rafters on the east wall of the garage at the left side of each photo as proof that the photos were taken in the morning rather than in the evening. This proof is based on a simplified estimate of the required brightness of a cloud in the east to create shadows on east wall of a structure. Sheaffer concluded it was _physically impossible_ for a cloud to create the shadows such as those on the garage wall. Having rejected the evening as the time of the photos Sheaffer estimated that the actual time, assuming that the sun was due east of the garage wall, was about 7:23 AM PST when the elevation of the sun was about 25 degrees. The shadows are illustrated in Figure 3, which is a highly magnified portion of the image of the garage wall shown in Photo 1. Klass has argued that the motive for saying that the photos were taken in the evening rather than in the morning (assuming a hoax) was to make the lack of reports from other farmers more plausible because, according to Klass, around 7:30 PM "most farmers have retired to their houses for dinner..."(2) However, by Klass' reasoning, the lack of reports from other farmers would also be explainable if the photos were not a hoax and an "extraordinary flying object" did fly by in the evening. In order to determine whether or not the shadows could have been made by any source other than the sun, specifically, a brightly reflecting cloud east of the garage, I have (a) analyzed the shadow images to determine whether or not they are consistent with shadows caused by the sun and (b) observed and photographed shadows made by bright clouds in the east at sunset. These two approaches to the problem have shown that it is _physically possible_ for a cloud in the east to cause shadows on an east wall at sunset and that the actual shadows on the garage wall are more diffuse at their edges than would be expected for sun shadows. Hence the possibility that a bright cloud in the east made the shadows on the Trent garage cannot be ruled out. Regarding (a) above, careful densitometric measurements of the relative brightness variations of the edges of the shadows on the image of the garage wall using the original negatives. These measurements are outlined in detail in Appendix A. They show that the shadows under the edge of the roof are more diffuse than would be expected from morning solar illumination, even on a hazy day. I have made experimental measurements of brightness vs. position across shadow edges using a scanning apparatus outdoors during clear and cloudy days. The shadow on a surface was created as a simulation of the Trent garage shadows. (The shadow was created by a simulated eave; the shaded portion of the simulated wall surface was illuminated by skylight.) These measurements demonstrate that the effective angular size of the solar disk increases with an increase in cloud thickness. This is important because the effective angular size of the sun determines the width (or "thickness") of the "edge" of the shadow. I call this width the shadow gradient distance or "shadow gradient region." This is the distance, measured perpendicular to the boundary line between the shaded and dark areas (i.e., perpendicular to the "edge" of a shadow), over which the amount of light on the surface (on which the shadow appears) goes from maximum brightness (direct sunlight outside the shaded area) to minimum (no direct sunlight; shaded surface). An increase in effective angular size of the sun increases the width of the shadow gradient region. The amount of increase in effective angular size is strongly dependent upon how the "effective angular size" is defined. In these experiments the measured widths of the gradient regions for various cloud conditions were used to define effective angular sizes of the sun. The experiments indicated that the effective angular size _may_ be as much as 2.5 to 3 times the actual angular size of the sun (0.53 degree) when clouds covering the sun are sufficiently dense that the brightnesses of shaded and unshaded areas differ by only 1% or less. By comparison, the width of the gradient region of the shadow under the edge of the roof of the Trent garage is 10 or more times greater than one would expect if the shadows were made by the unobscured sun (see Appendix A) . Even if one assumes that the sun were partially obscured by clouds so that the contrast in brightness between fully illuminated and fully shaded areas agrees with the contrast in the Trent photos, the width of the garage shadow gradient region is 4 or more times greater than expected if the (partly obscured) sun were the source. Thus the horizontal shadow data (the "edge" of the horizontal shadow of the roof) indicates that a source with an angular size in the vertical direction that was much larger than the angular size of the sun was east of the Trent garage when the photos were taken. Besides the horizontal shadow under the edge of the roof there are also shadows of the ends of the roof rafters. Sheaffer analyzed these shadows and concluded that the angular size of the source might be more than 1 degree in the horizontal direction. (7) Scanning densitometer data from these small images are sufficiently noisy to be somewhat equivocal on the angular size of the source in the horizontal direction, but they appear to indicate an angular size in the range 3 to 4 degrees. Taken together, the widths of the "edges" of horizontal and vertical shadows suggest that the light source may have had an angular size of more than 5 degrees in the vertical direction and 1 to 4 degrees in the horizontal direction. Thus the shadows seem inconsistent with what would be expected if they were caused by the sun. As explained in Appendix A, one does not expect the edges of shadows made by the sun to be noticeably diffuse, even when the sun is partly obscured by clouds. An alternative source of light of relatively large angular size would be an brightly reflecting cloud east of the Trent garage at sunset. In order to resolve the question of whether or not a cloud could produce such shadows I first carried out a theoretical investigation making use of sky and cloud brightness data. Although the investigation was not conclusive, it did indicate that shadows such as appeared on the Trent garage might occur if a brightly reflecting but not too large cloud were optimally illuminated. Conclusive evidence that clouds can produce rather sharp shadows was obtained in Maryland in the summer of 1977, and is presented in Figures 4a and 4b. One evening I observed a cumulous cloud east of my house which made shadows of the edge of the roof at sunset. As quickly as possible, I obtained my camera and photographed shadows of the edge of the roof and also of a board which I leaned against the house. The cloud which produced the shadows was not particularly bright and had an angular size of about 5 or 6 degrees in diameter. Unfortunately the cloud had dimmed somewhat by the time I got the camera and began taking photos of a board leaning against the wall under the eave shown in Figure 4. I believe that, had I been able to take photos when I first noticed the cloud, the shadows would have been more distinct and sharper. The cloud made shadows which appear to be quite sharp, as do the shadows on the Trent garage. In an earlier "sighting" of cloud shadows (during the late summer of 1976 when I had no camera available) I observed shadows made by a cloud that was about 2 to 4 degrees wide by about 8 to 12 degreees high (estimated by the "finger technique.. ...a finger at arm's length subtends an angle of about 2 degrees). This cloud, illuminated at sunset, was bright enough to make a shadow of my finger (3/4" wide) on the white surface of a car when my finger was about a foot from the car with no shading of a portion of the sky (no "eave"). This earlier sighting took place in Florida , while the photographic evidence was obtained in Maryland. I have since been informed of an observation of cloud shadows in San Francisco. (5) Thus it appears that, contrary to the opinion advanced by Sheaffer (7), it is physically possible for illuminated clouds to make shadows similar to those on the Trent garage wall. (NOTE 2000: several other people have mentioned seeing such shadows since the preceding statement  was written.) Having shown that cloud shadows can occur, it would now be necessary to demonstrate that there was a brightly lit cloud east of the Trent garage at about 7:30 P.M. on May 11 , 1950. This is, of course, is impossible to do (without resorting to the shadow data in the Trent photos). However, the weather reports for both McMinnville and Salem, Oregon indicate that there were cumulous clouds in the area during the afternoon of that day. Both of these weather reporting stations are east of the Trent farm (the McMinnville station is northeast and the Salem station is southeast). Besides the shadow data, there are also other brightness data in the Trent photos which suggest that the sun was not the source of light east of the garage. The brightness scale, to be described in a later section, is much lower than one would expect if the early morning sun at an elevation near 25 degrees were the light source. The verbal testimony of Mrs. Trent also has a considerable bearing on whether or not the photos might have been taken in the morning. In many conversations (by phone) with Mrs. Trent I asked her questions which, I believe, she had never been asked before, at least not in relation to the UO photos. Some of these questions had to do with the daily activities of the Trents. Her answers were quite consistent during the three year period of our conversations. According to Mrs. Trent, she was "out feeding the rabbits in the yard alongside the garage" (9) just before she saw the object. (She said the same thing to Hartmann.) I therefore asked her, in several different conversations and in different contexts, when she fed the rabbits. She replied that she fed them in the morning before going to work (i.e. , before 8:00 AM) and in the evening. I also asked her what their usual morning and evening activities were "back in those days." She recalled that she and her husband would arise about 4:30 AM and take care of the animals in the barn (cleaning, milking, etc.). After finishing these chores and eating breakfast Mr. Trent would drive a truck from farm to farm collecting milk for transport to a local dairy. His "milk run" began between 5:30 and 6:30 AM, and he usually did not finish until after 10:00 AM, depending upon the number of farms he had to visit. Mrs. Trent pointed out that this milk run took place daily except under unusual circumstances (sickness, very cold weather). In the afternoon Mr. Trent worked at the Alderman berry farm . He would have been home in the evening after about 6:00 PM. (10,16,17,18) Besides the farm chores, Mrs. Trent had to take care of her children (whom she left with her mother-in-law who lived several hundred feet west of them) before going to work at about 8:30 AM with a friend. She worked at a chicken cannery until late in the afternoon. Thus the daily schedule of the Trents strongly suggests that they would not have had time for perpetrating a photographic hoax in the morning. Moreover, their schedule indicates that Mr. Trent would not even have been home in the time frame suggested by Sheaffer. Consider the following question: if it was a hoax, why did they do it at a very inconvenient time during the morning of a weekday when they had many other things to do in the morning? If it was a hoax they could have made the photos at any convenient time such as, for example, the evening. Clearly the Paul and Evelyn were very busy people in those years. They had plenty to do besides thinking of ways to create a photographic hoax to "prove" the Mrs. Trent had actually seen "flying saucers" three times before, as suggested by Klass(2). (Note: her previous sightings might have been misidentifications, as are the bulk of UFO reports. She also said she had seen some UFOs in the years following the photos but they were much farther away. Of course, if the original sighting had been a hoax, a very successful one at that, they might have easily taken more photos in later years, but they didn't.) If the Trents had publicized their photos widely and had tried to capitalize on their success one might be tempted to think that they had created a hoax for monetary gain. However, as pointed out by Hartmann, there is no indication that the Trents ever received any money for their photos, nor is there any indication that ever even tried to capitalize on their photographs. 

The last sentence of reference 9 states that the sky at 7:30 PM was "overcast at 5000 feet". Hartmann indicated that this sort of cloud cover was "confirmed" by the photos (1). Klass (2) obtained the McMinnville airport weather report and found a meteorological symbol which he interpreted as meaning "perfectly clear. Actually the symbol means "less than 10% sky cover," thereby allowing for the presence of some clouds within 5 - 10 miles of the airport and any number of clouds farther than 15 miles(19). (The airport weather observer is primarily interested in the cloud conditions near the airport where they could affect take-offs and landings.) The McMinnville airport is about 12 miles northeast of the former Trent farm. Another nearby airport, at Salem, Oregon, is about 17 miles southeast of the farm. The Salem airport at 7:28 PM reported altocumulus at about 12,000 ft covering about 10% of the sky and cirrus at 25,000 ft covering about 25% of the sky. Both airports reported cumulus clouds, which are puffy clouds with considerable vertical structure in the afternoon. The Salem airport indicated about 10% sky coverage with cumulus clouds at about 3000 ft from 12:28 PM to 3:28 PM. According to various residents of the area with whom I have spoken, the weather conditions near the coast of Oregon are quite variable, so conditions reported by the airports may not have been exactly the same as conditions nearer the coast where the Trent farm was. Both airports reported a light (10 mph) wind blowing toward the east or northeast, and visibilities of 15 miles or greater. For comparison, at about 7:30 AM PST, according to the McMinnville airport, the sky was "clear" (i.e., less than 10% sky coverage) . According to the Salem airport the sky was 40% covered with cirrus clouds at about 25,000 ft. Visibilities were in the 12-15 miles range and the wind was negligible. As Klass has pointed out, the McMinnville airport reported "smoky" conditions, which is interpreted as meaning smoky or hazy. No such conditions were reported at the Salem airport, although earlier in the morning there was some ground fog near the Salem airport . The photos neither confirm nor deny the sky conditions given by the airports. The photos show a sky which brightens toward the west, but is otherwise quite featureless. As pointed out by Sheaffer (7), such a brightness distribution can be consistent with the sun being either in the east or the west because of the nature of the scattering of light by small particles and molecules. There does appear to be a sort of haze over the distant mountain tops. This seems to be a real image rather than a fault in the development of the negatives . The "haze layer" does not have much contrast with respect to the sky, but it does appear slightly darker than the sky. Whether this is a relatively nearby haze or a distant, very thin cloud cannot be determined. However, if this were a distant cloud being illuminated by the sun in the east, one might expect it to appear brighter than the surrounding sky rather than darker, since water drops scatter light more stongly than clear air. On the other hand, if the source of light were in the west and the light were therefore coming through a thin cloud or haze layer, then less light would get through where the cloud is thickest and this could make the cloud appear darker than the surrounding sky. Because the photographs can no longer be used as positive proof that the photos were taken in the morning, and because the daily activities of the Trents made it unlikely or impossible for Mr. Trent to have taken the photos at about 7: 30 AM., it appears that the weather conditions at the time of the sighting were those conditions prevailing at about 7:30 P.M. on May 11,1950. 


According to the original sources, Mrs. Trent had been feeding the rabbits which were in a cage located south of the house and at the east side of the southern garage wall (1, 8,9,10,12,20) (Hartmann's report is considered to be an original source since he actually interviewed the Trents) . She had just started walking back toward the house when she first saw the object. She yelled to Mr. Trent who was in the house (1,9,10) and they both scrambled to find the camera (see footnote 60). As soon as they found the camera Mr. Trent ran into the back yard south of the back door of the house and, looking toward the northwest, he saw the object moving southward. (NOTE 2000: it is likely that he heard her yell from the back yard, found the camera and went running out to approximately where she was standing and then he saw it and took the pictures from there.) Holding the camera at stomach or chest height and looking down into the viewfinder he took two pictures, pausing between pictures only long enough to wind the film in the camera. Available verbal and photographic data indicate that he took the photos from locations about 20 feet south of the house and 30 feet east of the garage. Because the object was moving southward he moved several feet to his right and a foot or so eastward to take the second picture. Both of the Trents also saw Mr. Trent's father and mother on the back porch of their house about 400 feet west of their house (9). They yelled to the in-laws to look and Evelyn ran into her house to call Paul's father and mother on a private telephone line. (9) According to Evelyn, there was no answer on the phone so she ran back into the yard in time to see the object vanishing in the west. Paul's mother had apparently gone into the house, probably to answer the phone, because she was no longer on the back porch of the other house when Evelyn came back outside. Apparently Paul's father heard Paul and Evelyn yelling and looked westward in time to see a distant shiny object fading into the distance (21, 22, 23). Paul and Evelyn think that Paul's mother may have seen the object, but they are not sure (25). During the interviews with reporters the Trents did not mention that Mr. Trent's father had also seen the object because they did not want his parents to be bothered by reporters, especially since Paul's mother was sick with cancer at the time. (25) 


All the original sources of information agree that the object approached from the north-northwest at a rapid rate of speed. An estimated path of the object is illustrated in Figure 5. This map is based on the general approach and departure directions and also upon Mrs. Trent's statement that it never actually-passed over their farmhouse but rather that its point of closest approach may have been near the distant farmhouse that appears in both photographs. (26) That farmhouse is on the west side of the Salmon River Parkway according to Hartmann (1). During an interview with Dr. James McDonald in 1969 Paul said that the object might have been a thousand feet away but certainly no closer than 400 feet (24). Hartmann included a loop in the flight path of the object, probably as a result of talking with Paul Trent. (Evelyn didn't mention a loop to me. However, if she ran inside to call her in-laws she might have missed a loop in the flight path (see the illustration labeled TrntHrtmnn1.jpg). I never talked to Paul because he didn't like to talk on the phone because of his hearing problem. ) This suggests that the flight path may have been more complicated than the path illustrated in Fig. 5. Mr. Trent reported that the object climbed rapidly during departure and that he didn't have time to run around the garage to see it and photograph it once more. According to reference 9, he found his camera and "took two shots. During this time the object moved across the horizon through an arc of about 15 degrees according to her description." (Note: this quantitative estimate was probably made by the reporter who interviewed Mrs. Trent for the newspaper article rather than by Mrs. Trent herself.) This quantitative estimate of the angular motion of the object across the western sky is surprisingly close to the actual angular displacement (change in direction) as determined by comparing the sighting directions in the two photos. The sighting direction to the UO in photo 2 is about 17 degrees to the left of the sighting direction in photo 1. (Mrs. Trent would have had to be quite lucky to have described a flight path that would have given about a 17 degree spacing between sighting lines if the object had actually been a small model hanging under the overhead wires, as suggested by the hoax hypothesis of Klass and others (1,2,7).) 


The elliptical shape of the image in photo 1 suggests that the Mr. Trent photographed a circular object seen from below and to the side (an oblique view). The witnesses described it as "bright, almost silvery" (8) or "brightly metallic, silver or aluminum colored, with a touch of bronze"(9). When Hartmann interviewed the Trents in 1967 they repeated their general descriptions, adding that it seemed silvery on top and more bronze on the bottom, that it was "shiny but not as bright as a hub cap", and that it resembled a dull, aluminum painted tank ."(1) These descriptions are consistent with the brightness distribution of the images in the photographs. The bottom of the image in photo 1 is clearly darker than the image of the top part, but probably most of this darkening results from the fact that the lower surface is shaded from the sun. There is some indication that the left edge of the object as seen in photo 1 is not a perfectly round contour, but may actually be more pointed, as illustrated in Figure 6. Figure 6 contains tracings of 40X blowups made by Hartmann. At such large magnifications the fuzziness of the edges of the images becomes apparent, and therefore the solid boundary lines in the figure indicate only the apparent edges of the image. To within the accuracy of the photographic medium, it appears that the left edge is not perfectly circular. A small drawing illustrates the outline as seen from above which would be consistent with the photos. The blowup of photo 2 shows, again to within the accuracy of the photographic medium, that the right and left edges are not identical. Moreover, the "post" on the top is not centered (it is slightly to the left of center) and it tilts slightly to the left. In both the tracings of photo 1 and photo 2 the density of crosshatch lines is intended to indicate the relative darkness of the surface. The post tilts to the left at an angle of about 5 degrees. It is not uniformly bright. It appears darkest near the main body of the object and at two small regions ("dots") near the top. These dark dots at the top are also seen in photo 1, just barely protruding above the main body of the object. The length of the elliptical image in photo 1 is 2.92 mm and in photo 2 the length is about 2.55 mm. The thickness (vertical dimension) in photo 2 is about 0.48 mm. Assume that Mr. Trent was standing roughly 16 ft from the nearby electrical wires which appear at the top of each photo. Since the camera focal length was about 103 mm ( 27), if the object were a small circular model UFO hanging from the wires at the time of photo 1 the size would have been about (2.92 mm/103 mm) x 16 ft = 0.45 ft = 5.4". On the other hand, if it were at a distance of about 1/2 km (not a hoax!; see Fig. 5) it would have been about 14 m in diameter. The thickness, using the vertical measurement from photo 2 , would have been about (0.48 mm/103) x 16 ft = 0.074 ft = 0.95" if under the wires and about 2.3 m if at a distance of 1/2 km . The diameter of the pole would have been about 0.38" if at a distance of 16 ft, and about 0.92 m if at a distance of 1/2 km. (NOTE 2000: during a re-investigation in the year 1999 it was determined that the camera was of a type - see below - which had a rated focal length of 100 mm rather than the 103 mm assumed in 1977 when this paper was written. Hence the calculated sizes should be increased by 3%, an amount which is comparable to the "noise" in the dimensional measurements themselves because of the natural diffuseness of the edges of photographic images, even when well focused, as these are.) 


A) Resolution The photographs were taken with a Kodak Monitor or Vigilant type of camera (the original camera was lost years ago) which had either a f/4.5 or f/6.3 ( the least expensive) lens. The rated focal length with the bellows extended and locked was 103 or 105 mm. (I have used 103 mm (27).) (NOTE 2000: through the joint efforts of Brad Sparks, David Silver [President of the International Photographic Historical Society], Terry Halstead and Joel Carpenter in 1999 it was determined that the camera was actually a "Roamer 1" built by the Universal Camera Corporation rather than a Kodak type which had been assumed during the early analysis. The focal length for this type of camera was about 100 mm. The minimum f-stop was 11 and the shutter was fixed at about 1/50 second.) The camera was evidently well focused, and perhaps a large f# was used (like f#22), since distant telephone wires can easily be seen in the photographs. The most distant wires were probably over 60 m away. Using a wire diameter of about 0.6 cm (1/4"), the angular width of the distant wires would have been about 0.0001 radians . Experiments with detection of small linear structures (e.g., threads) by photographic means indicate that if there is sufficient contrast between the structure and the background a linear image structure much smaller than the grain size of the film can be detected. Since the grain size of the film used by the Trents was on the order of 5-10 microns, linear structures with images as narrow as 1 micron might be detectable, corresponding to angular sizes of about 0.001 mm/100mm = 0.00001 radians (where 1 micron = 0.001 mm). This would correspond to a thickness of about 0 .05 mm at a distance of 5 meters (about 16 ft) , which would have been the distance to the object if it had been hanging under the overhead wires. A typical thread is about 0.03-0.06 mm in diameter. Images comparable in size to the film grain are very "bumpy'' or rough. The film grain accounts for a portion of the blurring of the edges of the images in the photographs. This blurring is especially apparent in high -power blowups of images . Other contributors to image blur are diffractive ("MTF") effects and perhaps a slight amount of imperfect focus or motion blur. Nevertheless, in spite of the slight blurring effects, it appears that the photographs should have been able to detect a linear structure as small as a thread under the illumination conditions prevalent at the time if the thread had a high contrast relative to the background sky, for example if it were either black or white, but not if it had been color matched to the sky. No such structure has been found in any analysis of the photographs. 

B) Photometric Estimate of the Distance of the Object The relative brightnesses of various objects appearing in the photographs allowed Hartmann to estimate the distance to the object by making some assumptions about its intrinsic brightness or reflectivity (1). (The photometric analysis of Hartmann was criticized on fundamental grounds by Sheaffer (2,7,14) and myself (27). Hartmann noted that the image of the bottom of the object in photo 1 (i.e., the dark elliptical image), which was presumably shaded from skylight, was nevertheless brighter than any of the other shadows in the photo. He then argued that the excessive brightness would be consistent with an object that had an intrinsically dark surface (i.e., appears dark when viewed close up and is not a source of light) but which was at a considerable distance from the camera. Light scattered by the atmosphere between the camera and the object could increase the _apparent brightness_ of the surface (the apparent brightness is the brightness that it appears to have when viewed over a long distance). He used a simple formula (the "contrast reduction formula" based on exponential extinction in the atmosphere) that relates intrinsic brightness, apparent (i.e., photographic) brightness and object distance to predict the distance for various assumed intrinsic brightness levels of the bottom surface. His calculations led to an estimate of about 1 km to the object in photo 1, even if the bottom of the object were as intrinsically bright as one could expect for a maximally diffusely reflective surface, that is, for a white bottom. If the bottom were intrinsically darker than white (say, bronze colored, as reported by the witnesses) the calculation implied an even greater distance. (NOTE 2000: in my calculations I assumed a white bottom, thereby biasing the result toward the hoax hypothesis of a neaby object.) Sheaffer was the first person to point out that veiling glare could account for the excessive brightness of the bottom (2). I undertook a study of veiling glare and published a rather comprehensive paper on the subject (with no reference to the McMinnville photos) in a technical journal (28). During the study I determined how much veiling glare would have added to the brightness of the UO image so that I could subtract the veiling glare leaving the true image brightness. I also discovered a factor not accounted for by either Sheaffer or Hartmann which affected the estimate of the intrinsic brightness of the bottom surface of the UO. The complete details of the revised calculation were published in ref. 4, along with the conclusion that, if the bottom surface were white but not itself a source of light, the object would have been about a kilometer away. This calculation has not been challenged.(14) However, as I pointed out (4), this does not prove that the object was distant, because the bottom surface could, possibly be a source a light. The uniformity of the brightness distribution and the small size of the object (if hanging under the wires) would rule out an internal source of light such as a small light bulb. However, if the hypothetical model UO were translucent, light from the sky or from the source which produced the shadows could travel through the UO and out the bottom, creating an excessively bright bottom. Experiments with simple paper models under illumination conditions such as prevailed at the time indicated that a simple paper model might not yield a sufficiently constant brightness bottom (the bottom surface closest to the light source would be brighter than the portion of the bottom farthest from the light source) . However, the experiments did not rule out the possibility that a model might be constructed out of some material in such a way as to create a uniformly bright bottom. The general conclusion from the photometric analysis of the UO is that the brightness is consistent with the witness' claim that the object was approximately over the distant farmhouse or farther away, as indicated in Figure 5. The photometric analysis did not, however, prove that the object was distant. 

C) The Brightness Scale of the Negatives The most noticeable overall feature of the negatives is the apparent underexposure (Hartmann referred to the negatives as "thin"). The lack of high photographic density regions (regions of high brightness, such as the sky) suggests that the f stop setting was not correct for the amount of light available. (Another possible explanation for the "thinness" of the negatives which I considered (4) was that the negatives had been underdeveloped. However, a comparison of the "fog densities" - in regions of the film which had not been exposed to light - indicated that the film was developed at least to a film "gamma" rating of 0.4 , and probably to a gamma of about 0.6 to 1.0. Standard development procedure required that film be developed long enough to reach a gamma of 1.0) A quantitative measure of the degree of exposure of a film is called the brightness scale. The brightness scale is the ratio of the brightness of the brightest area of the photograph to the brightness of the most shaded area. In the Trent photos the brightest areas are in the image of the sky, and the darkest areas are in the image of the shadow under the nearby tank. (NOTE: if the sun in the east were light source one would expect the brightest part of the photo would be the reflection from the tank rather than the western sky.) The brightness scale for the Trent photos is about 13. This can be compared with the scale of 30 or more expected if this were a "front-lit" scene with the light source behind the photographer, i.e., if these photos were taken in the morning and the light source was the sun (e.g., the sun east of Mr. Trent and the garage wall). Jones and Condit (30) found that the brightness scale of front-lit scenes in which the sun was the source of light (clear days) ranged from 40 to 600. Even when the sun was largely obscured by clouds the brightness scale was greater than about 30. Thus the brightness scale of the Trent photos seems quite inconsistent with the claim that the source of light was the sun east of the garage. The low brightness scale would not be inconsistent, however, with the lighting conditions at sunset when there was a bright cloud east of the garage because the cloud would not change the brightness of the western sky , and because the generally uniform lighting near sunset would result in a low brightness scale for any photographs, regardless of the direction in which the photographs were taken. If the photos were taken near sunset then the low overall exposure of the negatives is consistent with the hypothesis that Mr. Trent did not take the time to change the camera settings (shutter speed and f stop) from the values which were used when he took the previous pictures on the roll. According to Mrs. Trent the previous pictures were taken during bright daytime conditions (a snow scene and a picture of a tree in the front yard of his house (31) ). Considering that the previous photographs had been taken during bright daytime conditions, it is probable that the camera settings were in the range f/16 to f/22 and 1/50 of a second when Mr. Trent photographed the UO. On the other hand, these same settings would probably not have produced underexposed negatives if the pictures had been taken in the morning when the sun was at an angular altitude of more than twenty degrees (32). The rather low brightness scale and exposure level of the UO photographs indicate that the photos probably were not taken in the morning. On the other hand, the brightness scale and general exposure level of the photographs are consistent with the witness's claim that the photos were taken in the evening. Furthermore, they are consistent with the hypothesis that a bright cloud in the east could have produced the shadows on the garage. 

D) Photogrammetric Analysis of the Nearby Model Hypothesis Whereas photometry, discussed in the previous sections, is a study of relative brightnesses of objects, photogrammetry is a study of the relative angular sizes and relative directions of the various objects in the photographs. Photogrammetry and photometry are therefore independent types of analysis (e.g. , an object of large angular size could have any relative brightness, and an object of some particular brightness could have any angular size). In the first chapter of ref. 1, Dr. Edward Condon rejected the Trent photos on the basis of a comment by photoanalyst Dr. Everitt Merritt who said the photos were "too fuzzy to allow worthwhile photogrammetric analysis."(33) However, Merritt's statement did not justif'y Condon's implication that Hartmann's photometric analysis was wrong or not useful. In his summary Condon never mentioned Hartmann's conclusion . He only referred to Merritt's comment. This may have been a deliberate attempt to confuse the lay reader and thus to "hide" Hartmann's conclusion. I'm sure that Dr. Condon knew the difference between photogrammetry and photometry. Perhaps he hoped that the lay public wouldn't know the difference. The main intent of the photogrammetric analysis, apart from the simple estimate of actual size of the UO from its angular size once a distance has been specified, is to determine whether or not the photographic evidence is consistent with the hypothesis that the UO was a model hanging under the wires. Attempts at a truly accurate photogrammetric reconstruction of the sighting have been hampered by a lack of data on the distance of the photographer from the garage wall, the exact location of the overhead wires, and the distance from the garage wall to the Trent house. (All of these measurements could have been made by Hartmann when he visited the site in 1967, but he made no measurements. Unfortunately several years after Hartmann's visit the former Trent farmhouse burned down, and several years after that the garage was torn down. ) Nevertheless it has been possible to estimate the locations of the photographer and the overhead wires with some accuracy just from information contained within the photographs, combined with some educated guesses as to true sizes of objects near the garage. (NOTE 2000: the following analysis has been greatly improved by using aerial survey photos not available when this paper was written. Nevertheless it is being retained for historical reasons. The improved photogrammetric reconstruction of the scene is presented in the Addendum 1984 which follows Appendix B.) The analysis has considered the following questions: a) do the sighting lines cross underneath the wires and (b) is the ratio of angular sizes of the UO in the photos equal to the inverse ratio of distances of the photographer from the point where the sighting lines cross? If it were possible to show that the sighting lines crossed exactly under the wires, then one would have a rather unlikely occurrence if the UO were large and distant. Similarly, if the ratio of the angular size of the UO in photo 2 to the angular size of the UO in photo 1 were the same as the ratio of the distance of the photographer from the point of .intersection of the sighting lines when photo 2 was taken to the comparable distance when photo I was taken, one would have another rather unlikely occurrence if the object were distant. If both (a) and (b) occurred, the sighting lines crossed under the wires and the angular size ratio of the object equaled the ratio of distances to the sighting line crossover point, then the photogrammetric analysis would definitely point toward a nearby model rather than a distant object, since conditions (a) and (b) would be satisfied if a model were hanging under the wires, but would probably not be satisfied of the object were large and distant. The details of the analysis are presented in Appendix B. I have specifically pointed out the difficulties with the analysis in the absence of dimensional data. However, several attempts at reconstructing the area of the sighting such as is indicated in Figure B2 have yielded similar answers to questions (a) and (b) : the sighting lines do not cross under the wires and the object size ratio does not equal the photographer distance ratio. Of course, the failure to prove that the sighting lines cross under the wires and the failure to prove that the size ratio is the same as the distance ratio does not mean that the photos cannot be a hoax. If the UO were swinging toward and away from the photographer in a pendulum- like motion, or if the hypothetical suspension of the UO were moved along the wire between photos, the sighting lines would not cross under the wires and the two ratios would not be equal. Thus the most definitive answer I can give about the photogrammetric test is that the test does not prove the photos are a hoax. 


The history of the Trent photos is quite long and complicated. Some specific details will be presented later, but first let me summarize the history as told to me by Evelyn Trent in numerous conversations. After the photos were taken the Trents waited about three days (until Mother's Day) to finish off the roll of film (1,34). Then probably during the following week , they took the film to a local drugstore (1,8,35) to have it developed. It probably took a week or more for the film to be returned (35). The Trents showed the pictures to their family and some friends, and, in particular, to a boyfriend of one of Mr. Trent's nieces (12,36). This young man, Andy Horness, was in the Army and about to travel to Korea (he was killed on the way). He apparently took an interest in the photos and suggested that Mr. Trent take them to the local banker, Mr. Frank Wortmann, to find out if he might know what the object was. The banker, upon seeing the photos, called the local newspaper. A slightly different version of the story of how the banker happened to see the photos was revealed in a letter by Frank Wortmann to the late Dr. James McDonald. Writing to McDonald in 1969 Wortmann stated "It was several days later (i.e., after the photos were taken) that we heard of his picture, but he had not then had the film developed and we got him to have it cared for..." (37) Mr. Trent himself, in a phone conversation with McDonald in 1969, said "(We) didn't show (the pictures) around...(I) was talking to (my) local banker and he put it up in (the) bank window" (reconstructed from notes made by McDonald while talking to Mr. Trent on the phone (36) ) At this late date it would be impossible to reconstruct the exact sequence of events that led to the publication of the photos. On the same day that the banker heard of the photos (June 7, 1950), Bill Powell, the reporter for the local newspaper was contacted. He went to the Trent farm and interviewed the Trents at length (35). He also obtained the negatives which the children were playing with (he found them under the sofa). Trent was reluctant to release the negatives for publication because he was afraid he would get into trouble with the government. (35) He apparently thought that he had photographed some secret military device. However, Powell apparently convinced Mr. Trent that there would be no problem. The interest of Mr. Horness, who was in the Army, may also have had an effect on Trent's point of view. In one newspaper interview, when asked why he had delayed so long before saying anything about the photos, Trent responded that he was "kinda scared of it" . He then said " ...I didn't believe all that talk about flying saucers before, but now I have an idea the Army knows what they are." (10) Powell took the negatives back to the newspaper office and studied them as carefully as he could. He told me he "blew them up every which way" and couldn't figure out how the Trents might have faked the pictures. (35) He could find no evidence of tampering with the negatives, so he made large blowups of the complete negatives and published them on the front page of the newspaper along with a brief story. This appeared in the June 8, 1950 issue of the paper. It was at this point that the long Trent photo "saga" truly begins. The clarity and detail of the photos combined with the public testimony of the banker that the Trents were honest people and with the statement by Powell that he could find nothing wrong with the photos (Powell was _very_ convinced that the Trents would not have been able to carry off a hoax of this nature(35) ) made the photos instant celebrities. By the tenth of June the Trents' story was carried by the International News Service (INS) and was circulated throughout the USA and the world. Apparently the INS news story was based on a second interview carried out by a reporter for the Portland paper, Lou Gillette. Life Magazine became interested and included the pictures with a very short story of the sighting. Powell gave the negatives to Life with the understanding that the negatives would be returned to the Trents (who were never paid for the use of the negatives). The Trents also accepted an invitation to appear on a TV show, "We the People," which was produced in New York City. While on the show the Trents resisted efforts by the show staff to make statements which they, the Trents, considered unfounded. (1) They were also supposed to receive their negatives after the show, but the negatives were not returned.(1,12) The negatives were subsequently "lost" in the files of the INS in 1950, and were only found again as a result of the efforts of the Colorado University investigation (Hartmann) in 1967.(1) The negatives were in the files of the United Press International which had bought INS. After the Dr. Hartmann finished with the negatives he returned them to the UPI. However, since the Trents had never been paid for the negatives, Philip Bladine, the editor of the McMinnville News Register (he was also the editor in 1950, when the paper was called the Telephone Register) wrote to UPI on behalf of the Trents to obtain the photos. UPI sent the negatives to Bladine in 1970. When I called Bladine in 1975 to find out if he could help me located the negatives he told me they were on his desk! He had had the negatives for about 5 years, but hadn't informed the Trents! (I subsequently arranged with Mrs. Trent to borrow the negatives for research. In return I sent her excellent prints and copy negatives so she could make her own copies.) In retrospect it probably a good thing that the negatives were "lost" between 1950 and 1967 because they were well protected during that time, and therefore the photographic information was minimally degraded. Also, in retrospect, it is interesting to contemplate the amount of money which UPI may have made off the Trent photos, which must have appeared in hundreds or thousands of UFO publications since 1950, while the Trents received nothing but trouble and harassment (crank phone calls, letters, etc.) whenever their photos appeared in widely circulated publications. (According to Mrs. Trent, over the years they received phone calls, letters, and direct visitations from people who called them liars, hoaxers, and other uncomplimentary names. They have also been contacted by "true-believers" and saucer "nuts". In my opinion she maintained a remarkable degree of equanimity in the face of all this notoriety. In all the conversations I had with her she never once referred to the object as a flying saucer, nor did she try to convince me flying saucers exist, nor did she say, anything about alien contact, space brothers, or any of the saucer-related extraterrestrial mumbo jumbo which we sometimes hear from people whose sightings have become famous.) 


Apparently no reporters followed up on the Trent story after the visit by Lou Gillette on June 10 or 11, 1950. Since there were, at that time, no civilian UFO organizations, there were no further civilian investigations into the sighting until many years later. However, the Trents have claimed that there was a brief government investigation, and that claim is backed in part by Bill Powell. The first mention of a government investigation in a written document (at least the first mention that I was able to find) is in a letter from the late Frank Halstead (an astronomer) to Maj. Donald Keyhoe (a retired Marine pilot, author of the first popular UFO book and several other UFO books and the first director the civilian UFO organization called the National Investigations Committee on Aerial Phenomena (NICAP)). (NOTE 2000: NICAP ceased operation in 1980 and the voluminous files of about 10,000 sighting cases were turned over to the Center for UFO Studies.) The letter of April 18, 1959 states that Halstead visited the Trents and "I spent about an hour with them and they told me that the FBI came there and questioned them for several hours and some time later a man from the A.F. base from Denver, Colorado... This man spent a considerable time with them asking, but did answer their questions." Halstead also offered to make a tape recording of the Trents' story. Richard Hall, who was the executive secretary of NICAP at the time, responded to Halstead's letter, saying that NICAP would be very interested in getting a tape recording and "as a separate section of the tape, a description of the interviews the Trents had with the two FBI agents and the Air Force officer."(39) I don't know why Hall referred to "two" FBI agents since there is no written record of Halstead referring to two agents. Perhaps Halstead telephoned Keyhoe (or Hall) in relation to the interview and conveyed further information that way. (Note: apparently Halstead never did tape the Trents. As late as May, 1961 Halstead informed Keyhoe by letter that he still intended to tape an interview with the Trents, but there is no such tape in the NICAP files. ) The next mention of possible government involvement occurs in two sources in 1967. Mrs. Trent told Look Magazine that "Air Force officials investigated the sighting and took Geiger Counter readings but they didn't let us know anything." (40) The second source is the Portland Oregonian of Aug. 3, 1967 which says that Mrs. Trent reported that" 'two detectives' examined their house and furnishings after they reported the pictures. She didn't know why." (41) In a 1969 phone conversation with Dr. James McDonald, Paul Trent was asked "what he thought it was" and he replied as follows: "Thought it was something the Army was experimenting with. Don't say much about it now... because get so much fuss. FBI checked (us); came right out to where (I) was working and questioned (me). That was right at (the) time, 1950, three weeks after it got out in the papers. (They) gave no reason. (They were) just talking to (me) but (they) showed FBI identification (papers)." (Reconstructed from telephone notes by James McDonald (24).) In several conversations with me, Mrs. Trent recounted the story of "detectives" who visited the house while she was home. I asked her "Was that during the day when you were home or something?"(42) She answered "Yeah, it was later in the day. I don't know, it was probably about 4:00, say to 4:30 when he came in. Yeah, he went through everything. _Everything!_ (her emphasis) And I don't mean maybe! He never stopped (until he had everything spread out) on the table." I asked her if the man said where he was from and she answered "No. He even went where to where my husband was at work, on the Alderman farm there. He asked all different questions there." Mrs. Trent gave a rather graphic description of how the "detective" went through the dresser drawers and other drawers in the house looking for something and generally making a mess of the place and they didn't put anything back where it was supposed to be. She said she wasn't sure that the detective was from the FBI. She also said that there was another man, too, who spent some time outside the house as well as inside. Both men took lots of pictures. They were "throwing stuff up in the air 'n' taking pictures, 'n' trying all different things like that, too, garbage can lids 'n' stuff like that, but they went all through it just to see what they could find, I guess. They didn't find nothin', but that's what they said they had (to do), said it was their job, that's the way they worded it." Mrs. Trent did not recall whether or not they wore uniforms. Although I have not been able, to find any documents associated with an on-the-spot investigation by the Air Force, it would not be too difficult to imagine that one or more agents of the Air Force's Office of Special Investigations (AFOSI; basically a criminal investigative unit of the Air Force) did investigate the Trent sighting. During the period 1949-1951 the AFOSI was the agency charged with on-site UFO investigations on behalf Project Grudge (headquartered at Wright -Patterson Air Force Base in Dayton, Ohio; Grudge followed Project Sign and preceded the better known Project Blue Book ). There are no documents on the Trent case in the files of Project Blue Book itself (which include the files of Sign and Grudge; these files are all at the National Archives) other than responses to letters written in the mid 1960's for information on the case. Lt. Col. Hector Quintanilla, Jr., who was in charge of Project Blue Book in the mid 1960's, wrote to P. Klass in 1969 (44) "the Air Force never officially got involved in the analysis of this case. We don't even have a good print of the alleged vehicle." Actually, Project Blue Book must have had at least one print in 1966 because at that time Quintanilla requested an analysis of the photographs by the photo analysis branch. The photo analysis branch did not provide an analysis, however. Despite Quintanilla's answer to Klass, it is not impossible that the AFOSI investigated the sighting in 1950 and did not file a report with Project Grudge. A study of the microfilm record at the National Archives (45) has shown that not all of the files of the AFOSI were entered into the Grudge or Blue Book records. In particular, on roll 91 of the microfilm records (45) there is an AFOSI document entitled "Spot Intelligence Report" which discusses the "Flying Saucer Photograph (taken by ) Trent (of ) McMinnville, Oregon ". The spot intelligence report was filed in the records of the 19th AFOSI district office and a copy was sent to AFOSI headquarters in Washington, D.C., but no copy was sent to Project Grudge. (Therefore Quintanilla was not aware of it because it was not in the Grudge/Blue Book file of reports.) The date on the spot report is June 21, 1950. Apparently an agent of the AFOSI saw a newspaper article in the Vallejo (California) News Chronical of that date. The newspaper article, which was included in the spot report, featured the Trent photos along with a very brief summary of the sighting. The text of the spot intelligence report says that " Sgt. Lawrence J. Hyder", of the 1704th Air Traffic Squadron, Fairfield-Suisan Air Force Base in California, "advised this District that (Mr. Trent) and all the Trents are known to residents of McMinnville, Oregon as being substantial, solid, honest citizens of the community. Hyder said that while he was home on leave, approximately June 8, his home town paper, the 'Telephone Register' published these photographs on the front page with the story that Trent said the 'Saucer' was shining silver, made no noise or smoke, and shortly afterward disappeared over the horizon to the Northwest." There is no specific indication that the AFOSI took any action as a result of this report by Sgt. Hyder. However, I should point out that June 21 was almost three weeks after the photos had been published and that Mr. Trent told J. McDonald (in 1969) that the "FBI'.' men came "right out to where (I) was working and questioned me, three weeks after it got out in the papers."(24) An independent statement about government involvement was made by a reliable source, Bill Powell, the newspaperman who originally published the Trent's story. Powell volunteered the information (without any question about it from me) in a phone conversation in 1976. Referring to copy negatives and prints which he had retained at the newspaper office (the original negatives had, by this time, been "lost" in the files of the INS) Powell said, "Anyway, the damn Air Force latched onto them and I never did get them back." (35) He went on to say that "They sent in a plainclothes (man who) had the paper to do it" about "two weeks to a month after the pictures were published". Note that this time period agrees with Trent's claim that he was visited about three weeks after the pictures were published. Powell said that he wrote registered letters and sent telegrams to the Air Force but never got a response and never got the pictures back. Philip Bladine, the editor, wasn't in McMinnville on the day that Powell published the Trent photos, but he heard about the sighting when he returned. In a letter to P. Klass, Bladine stated that, after the negatives were sent to Life Magazine, "they (Life) claimed the negatives were returned but we never received them." (46) Bladine then stated that he had "always been suspicious that they were confiscated by military people." The military involvement was echoed, in a somewhat distorted manner, by Frank Edwards in an article published in 1965. (47) In 1950 Edwards was a radio commentator who had an interest in saucer sightings. Shortly after the Trent photos were published he arranged with Bladine to send out free reprints of the first page of the Telephone Register of June 8 (1950) to anyone who wrote for a copy. Edwards announced this offer during a radio program and, according to Bladine, the newspaper received nearly 10,000 requests for copies, and hundreds, or thousands, of letters. Because of Edwards' interest in the Trent sighting and his arrangement with the newspaper, he was in close contact with the newspaper in June of 1950. According to Edwards," the Air Force had picked up all the available prints from the McMinnville Tribune (sic), had 'borrowed' the original negatives from Life and tried and failed to secure the two prints in my possession." (47) The statement by Powell, backed up by Bladine and Edwards, strongly suggests Air Force involvement between two and four weeks after the pictures were published. On the other hand, Trent claimed that he was visited by FBI men. (Note: Mrs. Trent did refer to the visit of an Air Force Officer who spent quite a long time talking with her, but this was much later than three weeks after the sighting.) In order to confirm or deny the claim that FBI investigators were involved, in the fall of 1976 I filed a request under the Freedom of Information and Privacy Act. I was informed, in May, 1977, that a search of the files at FBI headquarters in Washington D.C. failed to turn up any information on Mr. Trent. However, from other information in the FBI file on "Flying Discs" I learned that the FBI had been instructed to investigate reports officially during the summer of 1947. The agents had then been instructed to discontinue official investigations, but to pass along any information they might acquire to the Air Force Office of Special Investigations.(48) Nevertheless, agents continued to send "disc" related information to headquarters during the 1950's. I also learned from agents at FBI headquarters that local FBI offices may carry out investigations and have the option of sending or not sending the results of these investigations to headquarters as the local agents see fit. Thus it is possible that local agents might have investigated the Trents and, having found no evidence of subversive activity (the official FBI investigation of 1947 had been directed toward the discovery of subversive activity), the local agents did not send the results of their investigation to headquarters. I also learned from FBI headquarters that, whereas the main office cannot destroy records (by order of Congress), local offices can destroy records after five or ten years. Thus there would no longer be any evidence of an FBI investigation of the Trents in any FBI files. Thus it is not possible to refute Mr. Trent's claim that he was visited by FBI agents. However, if plainclothes Air Force agents had interviewed the Trents they might have forgotten that they were Air Force agents and thought many years later (e.g., 1959 when questioned by Frank Halstead) that the men had been from the FBI (because they did not wear uniforms). If the Trents made an error in thinking that they had been visited by the FBI, then their story would agree closely with that of Powell (who said a plainclothes Air Force man visited the newspaper office) and their story would suggest that the report by Sgt. Hyder caused the AFOSI to investigate (although no record of such an investigation has been found). On the other hand, if both the Trents and Powell are correct, both the FBI and the AFOSI were involved. (NOTE: in the letter I wrote to the FBI asking for information on the Trents I also included a request for any other UFO related information they might have, under the then-recent rulings of the Freedom of Information and Privacy Act. I didn't expect to receive any other information since, as of 1976, there had never been any publicly available references to the FBI investigating UFO sightings. (In fact, in the 1960's the FBI had specifically denied being ever involved.) In May, 1977, I received a phone call from the very surprised FBI agent who had handled my request. He told me there were over a thousand pages of material in the "flying disc" file. Over the next few years about 1,600 pages were released and are now available on the web at the FBI site: Some of the sightings investigated in 1947 by the FBI were filed under "Security Matter - X"...the "real X Files!" The story of the FBI involvement with UFOs is told in my book "THE UFO-FBI CONNECTION" published in May, 2000, by the Llewellyn Publishing Co. The genesis of this book is the FBI documents which were released over 20 years ago as a result of my request. But I would not have made that request had the Trents not said anything about potential FBI involvement so, in some sense the writing and publication of this book is directly traceable to Paul and Evelyn Trent!) 


According to the brief story in Life Magazine of June 1950 "none of Trent's neighbors saw (the) saucer." (31) No other witnesses were mentioned in the initial newspaper accounts, although the attempt to contact Mr. Trent's mother by telephone was mentioned in the Portland paper (9). The first mention of other witnesses was made by Mr. Trent in a phone conversation with Dr. McDonald. (24) Mr. Trent said that his father saw the object as it was departing toward the west because he and his wife yelled to Trent's father and mother to look. Mrs. Trent told me that she thought her mother-in-law might also have seen it. She also talked about another possible witness whose name was Chapin or Chaplain. (Mrs. Trent could not remember the name exactly after so many years.) According to Mrs. Trent (21), Mrs. Chapin, with whom she was not well acquainted, came to her one day after church several weeks (or months) after the photos had been published and said " 'You know that object that you guys saw and took a photo of.....I think I saw the same object that same day you was (sic) talking about'. And then I ( Mrs. Trent) described it to her 'n' she (Mrs. Chapin) said, 'Yes, that's what it looked like. I just thought at first it was just some parachute. After I read that in the paper, I knew good 'n' well that that was the same thing I saw'." Of course, I do not expect that these are the exact words of Mrs. Chapin, recalled by Mrs. Trent after about 26 years. However, Mrs. Trent recalled the story told by Ms. Chapin in a similar way several times over the several years that I talked to her. The description of the object as resembling a parachute may have been an modification of Mrs. Chapin's alleged account. I say this because Mrs. Trent, in conversations with me and also in an original newspaper report, referred to the object as resembling "a good sized parachute canopy without the strings, only silvery bright mixed with bronze."(9) According to Mrs. Trent, Mrs. Chapin died around 1970, so she still would have been alive in 1967 when Hartmann could have interviewed her as part of his investigation. Unfortunately Hartmann never asked about other witnesses. McDonald asked Mr. Trent about other witnesses in 1969. Mr. Trent mentioned his father. He may not have known (or did not remember) about Mrs. Chapin, since Mrs. Chapin talked to Mrs. Trent. Although McDonald talked to Mrs. Trent as well as to Mr. Trent, there is no evidence that he asked Mrs. Trent about other witnesses. (24) In many conversations spaced over several years Mrs. Trent repeated her. claim about Mrs. Chapin (Chaplain). If she had been making this story up simply for my benefit, to bolster the credibility of the sighting , she must had have a remarkable memory for detailed falsehoods! (21,26,49,50) 


Over the years many people have visited the Trents to ask them about their sighting. Others who know the Trents, or who know of the Trents, have offered opinions as to the truthfulness of the Trents. For those readers who have not actually conversed with either of the Trents the following list of people who have talked to the Trents or who know of the them through intermediaries (friends of friends) will be of interest because of the quotable opinions of these people. I have listed these people in chronological order of their interactions with the Trents. 


Bill Powell June, 1950; wrote the original story "I think the photos and published the photos were authentic." The Trents were telling the truth.(35) 

Frank Wortmann June 1950; Trent's banker. Publicly vouched for Mr. Trent's He notified Powell about the photos. veracity; repeated his opinion in letters to McDonald(37) and Klass(51) 

Philip Bladine June,1950; editor of the paper; Believed the Trents knew the Trents, Powell, and wouldn't fake the photos (5). "We Wortmann always figured it was legitimate."(53) 

L.J.Hyder June, 1950; Air Force Sergeant who The Trents were known provided information to the AFOSI to residents of McMinnville as substantial, solid, honest citizens (45) 

Frank Halstead April, 1958; retired astronomer After an hour long interview he who traveled around the country gained the impression that the investigating sightings and sending Trents were "very sincere people" (38) information to NICAP 

William Hartmann 1967; photographic case From his description in the investigator for the Colorado Condon report and a UFO study ("Condon Report") statement to McDonald in a phone conversation it is clear that he was impressed with the Trents (1). However he also made it clear that he could not positively rule out the hoax hypothesis. He later changed his mind on the veracity of the sighting (6,54). 

James A. McDonald 1969-1970; atmospheric "I find them to be the physicist at the University kind of people who could of Arizona and independent scarcely carry off an investigator of UFO sightings imaginative hoax or fabrication"(55) 

Veikko Itkonen 1969; film producer and "The conclusions made by director; interviewed and Dr. William K. Hartmann filmed the Trents for a UFO in the Condon Report... documentary that was shown are very close to the in Europe impressions we got during our visit to McMinnville and meeting with the Trent family" (56) 

Arthur Fryer Dec. 1976; retired high "No question in my mind school science teacher in that they weren't trying McMinnville who interviewed to hoax. She never the Trents at my request called it a flying saucer or UFO"(57) 

B. Maccabee 1974-1977; physicist and "I have never detected any UFO investigator; had 26 tendency to hold back or conversations with Mrs. distort information intentionally; Trent (some short, some differences in various retellings long; most transcribed of the sighting and surrounding for later analysis) events seem to be no more than what one would expect of a person trying to recall events of more than 24 years before. 

This list of people who have interviewed one or both of the Trents is doubtless too short. However, these are the people who have made statements that I have on record. Also of interest are the opinions of two independent investigators who analyzed a tape I made of a conversation with Mrs. Trent. The analyses were made by voice stress analysts using equipment constructed by the Dektor corporation. One test was carried out by an employee of a security system company in Los Angeles (name on record (58)). The opinion of the chief examiner was "that the statements given by Mrs. Trent to the interviewer on this tape are true to the best of her knowledge." An independent study of the tape by C. Andrews of the Dektor Corporation led Ms. Andrews to state that there was little or no detectable stress in Mrs. Trent's voice when she answered questions about the sighting, about other alleged witness and about other subjects (59). Criticisms of voice stress analysis notwithstanding, the apparent lack of stress suggests that, at the very least, Mrs. Trent believes what she is saying. Perhaps if she were a pathological liar she could have avoided stress, but it would seem that at least one of the people who interviewed her personally over the years would have discovered that by getting her to make a statement which could be proven to be untrue. 


The Trent photo case is a classic because of its "age" and also because the object is depicted so clearly that it is either a model (hoax) or it is an "extraordinary flying object" (to use Hartmann's phrase). It certainly is neither a bird, nor a plane, nor Superman (i.e., not a misidentified object). This case is also a perfect illustration of the fact that, when trying to prove an extraordinary sighting is factual, it is not sufficient to have clear photographs and several witnesses. Ever since the photos were published explanations have been offered by people who never spoke to the Trents. These explanations have often been based on imperfect or incomplete investigations of the case. Unfortunately scientists were not interested in the case at the time that the photos were published, so the Trents were not interviewed in depth, the negatives were not carefully analyzed, and valuable data were lost forever. However, even though data are lacking, it appears from the analysis presented in this paper (and in the earlier CUFOS paper (4)) that there is no positive proof of a hoax. Rather, the available data, which do include a "life history" of the Trents since 1950, suggest that the sighting actually occurred as the witnesses claimed. The photos themselves, for reasons discussed earlier, are equivocal on the hoax hypothesis, although they strongly confirm the verbal statements if the case is not a hoax. Since the hard photographic evidence does not positively rule out the hoax hypothesis, the case will have to be resolved by studying the life history of the Trents since the sighting, and/or by a "confession". The preponderance of the information collected and analyzed by this investigator suggests that the life style of the Trents is not compatible with assuming that their very "successful" photographs resulted from a hoax . Only a confession with a description of how the hoax was carried off would now convince me that Mr. Trent did not photograph a large, distant object, the intrinsic nature of which has not yet been established. 

For an updated discussion see the ADDENDA. 


1. "Scientific Study of Unidentified Flying Objects," E.U. Condon, Director (Bantam, 1969, Pg. 396) This is the final report of the Air Force funded investigation carried out at the University of Colorado. (D.S. Gilmore, Ed.) 2. Klass, Philip J., "UFOs Explained," Random House, New York, 1974 3. Bulletin of the American Physical Society, 21, 623(1976) 4. Maccabee, B., "On The Possibility That The McMinnville Photos Show A Distant Unidentified Object," Proceedings of the 1976 CUFOS Symposium, pg. 152 , Center for UFO Studies, Evanston, Ill. 5. Ibid., pg. 234 6. "UFOs, A Scientific Debate," C. Sagan and T. Page, Ed., pg. 12 7. Sheaffer, R. "A Further Investigation of the McMinnville, Oregon Photographs", private communication (unpublished), and ref. 2 8. McMinnville Telephone Register, June 8, 1950 9. Portland Oregonian, June 10, 1950 10. Los Angeles Examiner, June 11, 1950 11. Dept. of Commerce, Ashville, N.C., weather records for McMinnville, Oregon, May 11, 1950 12. Mrs. E. Trent, private communication (Note: this refers to information obtained during 26 telephone conversations over the time period January 1974 through July 1977.) 13. Dept. of Commerce, Ashville, N.C., weather records for Salem, Oregon, May 11, 1950 14. Sheaffer, R., "The UFO Verdict," Prometheous Books , Buffalo, NY 1981, pg. 60 15. B. Sparks, private communication 16. E. Trent, July 9, 1976 , private communication 17. " , Feb. 3, 1974, " " 18. " , Dec. 9 1975 , " " 19. Key to decoding Aviation Weather Reports, Dept. of Commerce National Weather Service, Wash., D.C. 20. W. Hartmann, private communication 21. E. Trent, Feb. 22, 1976 private communication 22. " , Mar. 9 1976 23. " , Jul. 9 1976 24. McDonald, Dr. James E, notes made during phone conversations with Mr. P. Trent, Mar. 9, 1969, and with Mrs. E. Trent, Feb. 17, 1970 and Mar. 2, 1970 25. E. Trent, Oct. 25, 1976, private communication 26. " , May 29, 1976, " " 27. Maccabee, B. (see ref. 4) 28. Maccabee, B., and C. Grover, "Veiling Glare in Camera Lens Systems", Proceedings of the Society of Photo-optical Instrumentation Engineers, Volume 107, 158 (1977) 29. Claude Poher, private communication 30. Jones, L.A., and H.R. Condit, J. Optical Society of America, 11, 651 (1941) 31. Life Magazine, June 1950 32. Jones, L.A., and H.R. Condit, J. Optical Society of America, 38, 123, (1948) 33. See ref. 1, pg. 37 34. Life Magazine, June 1950 35. W. Powell, private communication, July 19, 1976 36. See ref. 24, Feb. 17, 1970 37. Letter from F. Wortmann to J. McDonald, May 5, 1969 38. Letter from F. Halstead to Maj. D. Keyhoe, Apr. 4, 1959 39. Letter from R. Hall to F. Halstead, May 5, 1959 40. Look Magazine, Flying Saucer Special, 1967 41. Portland Oregonian, Aug. 3, 1967 42. E. Trent, Feb. 3, 1974 , private communication 43. " , Jan.31, 1977 , " " 44. P. Klass, private communication (letter from Maj. Hector Quintanilla to P. Klass, July, 1969) 45. Microfilm files of Project Blue Book and the Air Force Office of Special Investigations at the National Archives 46. P. Klass, private communication (letter from P. Bladine, July 30, 1969) 47. F. Edwards, syndicated newspaper column, Aug. 1965 48. Maccabee, B. "UFO Related Information from the FBI File" published in monthly issues of the MUFON Journal, International UFO Reporter, NICAP Investigator, APRO Bulletin, during 1977-1979 49. E. Trent, March 9, 1976, private communication 50. " , July 23, 1977, " " 51. P.Klass, private communication (letters from F. Wortmann in 1969 and 1972) 52. P. Klass, private communication (see ref. 46) 53. P. Bladine, private communication, April 14, 1975 54. W. Hartmann changed his opinion about the Trent case after reading Sheaffer's analysis (ref. 7) which discussed three problems with the Trent case. According to Sheaffer: (a) there are shadows on the wall which prove that the photos were taken in the morning rather than as the witnesses stated (in the evening); b) one of the shadows moved on the garage wall between photos indicating a long time between photos (minutes) rather than tens of seconds as the witnesses stated; and c) veiling glare caused by grease on the camera lens could have made the UO image in photo 1 too bright, thus invalidating Hartmann's distance calculation. Points (a) and (c) are discussed at length in the text of this paper and in ref. 4. Point (b) was found to be in error after the original negatives were carefully investigated and no shadow movement was detected. 55. Letter from Dr. J. McDonald to W. DeFaria, March 26, 1970 56. Veikko Itkonen in a letter to Ole Henningsen, 5/19/77 and in a private communication to this author 57. A. Fryer, private communication, Dec. 10, 1976 58. Letter on file 59. C. Andrews, private communication 60. One may wonder how it happened that Mrs. Trent had the presence of' mind to think of a camera, when it is known that in some cases witnesses who have cameras near by have not thought to use them (see, for example "Missing Time" by Budd Hopkins, Richard Marek Publishers, New York, 1981 , pg 29). Her quick thinking may have been a result of previous sightings . According to ref. 9, Mrs. Trent had seen similar objects three times before. Whether these were bonafide sightings or misidentifications is immaterial as long as she thought she had seen similar things previously. Perhaps in the previous sightings she had wished she had a camera because, according to ref. 9, no one would believe-her. Apparently "no one" included her husband, because he was quoted as saying "I didn't believe all that talk about flying saucers before, but now I have an idea that the Army knows what they are"(ref. 10). But this time when she saw an unusual object she was home with her husband and she could prove it. Moreover, she knew that a camera was available, so she yelled to her husband to get the camera and he did. From the original stories and what she has told me it seems reasonable that she looked in the car while her husband, who was in the house, looked in the house for the camera. Klass (ref. 2) has used her claim to have seen objects three times previously as a "reason" for the presumed hoax, "Now, thanks to the photos, skeptical friends would be convinced." If Klass were correct, she must have convinced her husband before the photos were taken since hoax photos would not be proof for him. Either that or she convinced her husband to put on a blindfold and take pictures in the back yard while, unbeknownst to him, she hung a model saucer under the wires in line with the direction he was photographing. Then, after the pictures were developed, he was convinced. Klass (ref. 2) has also pointed out that the Trents are "repeaters," although, in fact, only Mrs. Trent reported several sightings before the photos and several afterward. This presumably means that the Trents have seen "impossibilities" occur more than once, which is highly improbable if UFOs are real, and, of course, impossible if they are not. Assuming with Klass that UFOs (saucers) are not real, then the repeated sightings must be either misidentifications or hoaxes. Since by this assumption the photos must be a hoax, then it is reasonable to assume that at least some of the later sightings were also hoaxes to bolster their story. But pushing this assumption to its consistent limit, and considering the success of the 1950 'hoax' photos, the Trents should have produced more photos to back up their claims of further sightings. Instead, according to Mrs. Trent (who, we are to believe, had a need to create a hoax to prove herself right in 1950) "We've seen quite a few since then, but we didn't get any pictures. They flew away too fast " (ref. 41). If the original photos were hoaxes, then Mrs. Trent's reason for not producing more pictures must be considered to be an excuse ... a "cop out". It would have been easy to produce more hoax pictures and apparently not time consuming since they managed to do it during one of their busy mornings in 1950, assuming the photos are a hoax. Perhaps the Trents were too lazy to produce more photos? But this seems inconsistent, since they are apparently very industrious people otherwise. Actually, the failure to produce further pictures in spite of the later sightings makes it seem more likely that the original photos were not the product of a hoax. 

61.I thank all of the respondents to my requests for information, including especially Mrs. Trent, Philip Bladine, Arther Fryer, Mrs. James MacDonald, and Philip Klass. I also thank Brad Sparks for helpful comments on sighting directions to the UO in the two photos. 



The images of the garage wall in both photos have been analyzed using a scanning densitometer to study the variations in brightness (density) of the images of the shadows under the garage eave. The densitometer scans have been done both "horizontally" and "vertically" on the images using scanning slits that are generally very small in the scanning direction (5 - 50 microns) and somewhat wider in the perpendicular direction (30 - 100 microns). The slit dimensions have been adjusted for each scan to maximize the signal-to-noise-ratio for a particular shadow image of interest in a particular scan. Representative densitometer tracings are presented in Figures A1, A2, and A3. Figure A1 is a "vertical" scan at 50X (magnification of 50 times) upwards under the eave near Rafter B (second from the right hand edge of the garage image). Figure A2 is a collection of similar scans at 10X at various places under the eave as denoted by I, II, III and IV. Figures A1 and A2 illustrate data from photo 2; similar data from photo 1 are illustrated in Figure A3. The bottom half of Figure A3 also illustrates "horizontal" scans through the images of the ends of the rafters and also, through the images of the shadows of the rafter ends in photo 1. The scans in the bottom half of Figure A3 give indications of the widths of the images of the ends of the rafters and also the widths of the associated shadows, as well as the brightness variations of the shadows. Figure A4 is a compilation of rafter shadow brightness data from photo 2. It is the result of the analysis of many parallel "horizontal" scans and it clearly illustrates that the shadows of the ends of the rafters get brighter (image density increases) as the distance downward below the eave increases. Figure A1shows that the "horizontal" shadow under the eave does not have a steep brightness (density) gradient in moving upward from the portion of the wall which is fully illuminated to the portion which is fully shaded from the source of light which caused the shadows. Instead, the gradient region is wide, apparently about 0.8 mm wide on the original negatives (Figure A1 is magnified 50 times). This is contrary to what would be expected if the bright source were as small in angular size as the sun. If the source were the sun one would expect a very narrow gradient region. One main objective of the analysis presented in this Appendix is to determine just how narrow the gradient region would be if the source were the sun, and to compare that calculated gradient width with the measured width in Figure A1. Although the calculated width of the gradient will only be compared with one (very carefully made) densitometer tracing of the shadow under eave (Fig. A1), analyses of similar gradient region density data taken at other locations in photo 1 and in photo 2 lead to similar conclusions: the width of the gradient region is wider than expected if the sun were the source. 

Calculation of the Expected Width of the Gradient Region if the Sun made the Shadows on the Garage Wall 

Using geometric optics as shown in Figure A5 (light travels in straight lines; diffraction effects are small enough to ignore) one can show that the width of the gradient region of the shadow caused by a source of angular size A in degrees, when projected past an edge to a surface at a distance R in meters from the edge is given by 

W = 2R TAN(A/2) (A-1) 

where TAN is the tangent function from trigonometry. Note that the brightness or illumination on the surface increases in a continuous manner from the fully shaded region to the fully illuminated region. The exact shape of the brightness gradient curve depends upon the overall size and shape of and brightness distribution over the surface of the light source. Figure A6 illustrates actual graphs of sun shadow edge gradients. These graphs were made by a scanning "brightness meter" (actually an "illuminance meter" that consisted of a resistively loaded solar cell with a small aperture and with the output voltage measured by a moving chart recorder that scanned the solar cell across the shadow edge). The shadow was created as a model of the Trent garage wall, i.e., a board representing the edge of the garage roof blocked part of the sky light when the brightness meter was not directly illuminated by the sun. The graph at the right side of Figure A6 shows the ratio of direct illumination brightness to the brightness when shaded by the "eave." This graph was made when the sun was partially obscured by haze or thin cloud. The ratio of the maximum brightness to the minimum, called Rb, for this graph is 3.17. When the sun is not obscured the ratio can go as high as 20 or so. As the sun becomes more and more obscured by cloud the ratio drops, as shown in the graph at the left side of Figure A6. The lowest ratio on that figure is 1.20. The effective width of the gradient region is indicated as Rs next to each graph. These data and many more similar data points were used to create Figure A7. In this discussion I ignore the exact shape of the graph gradient region in the photos because various photographic and instrumental effects have doubtless modified its shape. Instead, in the comparisons described below I use only the effective width of the gradient on the photos and from graphs such as in Figure A6. The shadow under the eave of the garage roof has a brightness gradient with a width determined by the angular of the sun, 0.53 degrees (in clear sky), and by the distance from the edge of the roof to the wall as measured along the (optical) path from the sun to the wall. The hoax hypothesis is that the sun was at an angular elevation of B degrees above horizontal. In this case, from Figure A6, the distance from the edge to the wall is the slant distance given by 

R = L/COS(B), (A - 2) 

where COS is the cosine function. There is one further addition to Equation (A -1) which accounts for the fact that the vertical wall surface is not perpendicular to the light rays . This makes the width W slightly greater than if the wall surface were perpendicular to the light rays. This addition results in the following equation for Wg which is the width of the gradient region on the garage wall: 

Wg = W/ COS(B) = 2 L TAN(A/2)/COS^2(B). (A - 3) 

The distance of overhang of the roof beyond the wall is not known, but a reasonable estimate based on standard construction is 6 to 12 inches. Choosing 10" as the distance, L , and with B = 16 degrees and A = 0.53 degrees , the width of the gradient region if the sun were the source would be 

Wg,sun = 0.10 inches (A - 4) (NOTE 2000: measurements made of the original garage show that the roof board extended about an inch beyond the end of the eave rafters which, in turn, extended about 6 inches from the wall. Hence L = 7 inches. In this case the gradient region width would be 0.07" Measurements made May 11, 2000.) 

To relate this width on the garage wall to the width of the gradient region in the image of the garage wall it is necessary to make use of the geometric relation between object sizes and image sizes that is established by the (focused) camera optics: 

Wg Iw ---- = ---- (A - 5) 
Dc F 

where Wg is the width of the gradient region regardless of what the light source was, Dc is the distance from the camera to the garage wall, Iw is the width of the image of the gradient region, and F is the camera focal length. In Appendix B I have shown that the camera was approximately 30 ft from the corner of the garage . As pointed out in the text, the camera focal length was about 103 mm. Therefore, using 30 ft = 360 inches, the width of the image of the gradient region, if the light source were the sun, would be (after rearranging Equation A - 5 appropriately) 

Iw,sun = F (Wg,sun /Dc) = 103 ( 0.1/360) = 0.0286 mm (A-6) (NOTE 2000: use of 100 mm as the focal length makes a trivial difference here) (NOTE 2000: use of 7" as the overhang makes Iw,sun = 0.020 mm) 

Now look at the brightness gradient curve in Figure A5. Note that the width of the gradient region is the distance from the edge of the low light level region to the edge of the high light level (unshaded) region . Figure A6 further illustrates this measurement on actual solar edge gradients. Thus the width Wg,sun can be found by measuring, on the image of the gradient region, the distance from the maximum brightness area to the minimum brightness area. Now look at Figure A1. There I have indicated the expected gradient curve if the sun were the source (unobscured sun--solid line) along with the measured gradient width of about 0.8 mm. Of course the gradient width which one would measure on the densitometer scan graph depends upon where one places the maximum and minimum brightness levels (the unshaded and shaded brightness levels). If we allow for the possibility that the brightness levels as indicated (solid horizontal lines) should be moved closer together, then the gradient width region would be reduced. Perhaps a width as small as 0.3 mm would be barely consistent with the densitometer data. Using this as a minimum measured value we can write the following equations for explicit comparison of predicted and measured image widths: 

Iw, sun = 0.029 mm (approx) (NOTE 2000: 0.020 mm) (A-7A) and Iw,photo = 0.3 to 0.8 mm (approx) (A-7B) 

where Iw,photo is the width of the image of the gradient region on the Trent garage wall. 

Effects of Cloud Cover on the Brightness Ratio and on the Effective Angular Size of the Sun 

The calculation just completed makes it clear that the shadow of the edge of the roof could not have been made by the unobscured sun, which has an effective angular size of 0.53 degrees . However, the relative brightnesses of the fully illuminated and fully shaded regions are not very different, which suggests that if the sun were the light source, it was partially obscured by clouds. More specifically, when the sun is not obscured by clouds the brightness of a shaded area (such as shaded area beneath the roof of the Trent garage) is less than 1/20 of the brightness of a fully illuminated area (such as the wall of the Trent garage below the edge of the shadow). As thin clouds gradually obscure the sun the brightness of the fully illuminated area drops rapidly, while that of the shaded area (which is illuminated by skylight and light reflected from the ground) drops relatively slowly, so that the ratio of the brightness of the illuminated area to the brightness of the shaded area decreases as cloud cover increases. In the Trent photos the ratio of the brightness of the illuminated area of the garage wall to the brightness of the shaded area under the eave is about 1.75, whereas the same ratio would be greater than 20 if the unobscured sun were the source. Thus I conclude that, if the sun were the source, it must have been partially obscured by clouds. The question then arises as to whether or not the effective angular size of the sun is effected by the presence of clouds. Specifically, forward scattering of light by ice crystals in the clouds may make the sun appear to be larger in angular size than it actually is. To answer this question I did some experiments in which I made a "model" of the garage wall and used a scanning "brightness meter" (which measures the relative amount of light or "illuminance" incident on a surface) to scan through the shadow gradient region created by the edge of the eave of the model garage. These and other experiments indicate that the effective angular size of the sun (as defined here in terms of the width of the gradient region) does increase somewhat as cloud cover increases. Figure A7 illustrates the experimental results. The brightness ratio, Rb, shrinks from some maximum value (sun unobscured) toward unity when the sun is completely obscured and there is no shadow. At this time the whole wall surface is illuminated only by skylight and ground-reflected light. As Rb shrinks the relative effective solar diameter, Rs, increases, perhaps reaching a number as high as 3. For Rb = 1.75, which is the value measured on the Trent photos (for gamma = 0.6; it would be larger if gamma were larger), Figure A7 shows that Rs may be as large as 2.5 - 3, meaning that the effective angular size of the sun might be as large as 2.5 x 0.53 = 1.3 degrees to 3 x 0.53 = 1.6 degrees. However, these measurements must be treated cautiously since instrumental effects and problems with the analysis of the scanning "brightness meter" data may have made the angular size ratios in Figure A7 _too_ large. However, assuming the data of Figure A7 are correct, one can repeat the calculation leading to the expected image size in Equation (A - 6). Using 1.3 degrees to 1.6 degrees as the effective angular size of the sun yields 

Iw,sun,maximum = 0.072 to 0.086 mm (A-8) (NOTE 2000: use of 7 inch overhang yields 0.050 to 0.060 mm) 

This range of values predicted for the width of the gradient region if the sun were the source are still about one quarter of the minimum estimated gradient width of the image on garage wall, 0.3 mm. Therefore, it appears that, even allowing for the possibility that cloud cover increased the effective angular size of the sun (a hypothesis which may be totally unique to the research reported here, I might add), the light source which made the horizontal shadow of the edge of the garage roof had a vertical angular size that was four or more times greater than the largest measured effective angular size of the sun. By reversing the procedure and using Equations (A - 3) and (A - 5) to calculate the angular size of the source in the vertical direction one finds that the source had an angular size of more than 5 degrees, with the actual size depending upon whether the gradient region width on the image is taken to be 0.3 mm or larger (up to 0.8 mm). The low brightness contrast and the corresponding large gradient region widths of other portions of the horizontal eave shadow (see Figure A2) confirm the conclusion that the light source was not as bright as the unobscured sun and had a vertical angular extent of 5 degrees or more. The vertical extent of the light source has been estimated from the width of the horizontal shadow made by a horizontal edge (i.e., the edge of the roof). It is also possible to make an estimate of the horizontal extent of the light source by looking at a vertical shadow, such as is made by the vertical sides of the ends of the eave rafters (2 x 4's). There are four shadows made by the ends of the four rafters (only three appear in photo 1). Figure A3 illustrates densitometer graphs (scans) that were made in a "horizontal" direction through the ends of the rafters and also through the shadows of the ends (lower half of Fig. A3). Figures A2 and A4 contain illustrations of the ends of the eave rafters and of their associated shadows. Figure A3 shows the rafter shadow densitometer graphs at the left of their associated rafter end graphs, and it also shows the rafter shadow graphs below their associated rafter end graphs. Of particular interest are the relative sizes (widths) of the rafter end graphs and the shadow graphs. The relative widths can easily be compared by eye by comparing the width of the graph of a particular shadow that has been shifted to the right (see notations on Figure A3) with its associated rafter end graphs just above it. In general the widths of the shadows appear to be slightly greater than the widths of the rafter ends. This is to be expected if the light source has a finite angular size (i.e., is not a source of zero angular size) as illustrated in the sketch in Figure A8. With a source of angular size A , the end of the rafter of width s, and the distance from the rafter end to the wall equal to R, the total width of the shadow, from the left side of the penumbra to the right side of the penumbra is given by 

W = 2[(s/2)+ R TAN(A/2)] = s + 2R TAN (A/2). (A - 9) 

If we again use ten inches as the distance of the rafter end from the wall, include the COS(B) factor to account for the fact that the light source is at an angular elevation of about 16 degrees, assume the source is the sun (A = 0.53 deg), and assume that the end of the rafter is 1.5 inches wide (standard for a so-called "2 x 4," then the total width of the shadow would be 

W = 1.5" +2(10)TAN (0.53/2) / cos(16)) = 1.6 inches (A - 10) (NOTE 2000: using 6 inches as th extension of the rafter end beyond the wall yields W = 1.56 inches) 

This assumes an unobscured sun.. If we allow for the possibility that the effective angular size of the sun had grown by a factor of three the total width becomes 1.78 inches (NOTE 2000: 1.68 inches). Thus the total width of the shadow of a rafter end is in the range 

Wrafter,sun = 1.6 to 1.8 inches (A-11) (NOTE 2000: 1.56 to 1.68 inches) 

Thus, if the sun were the source the maximum width of the shadow of a rafter end would be about (1.6/1.5) = 1.07 to (1.8/1.5) = 1.20 times the width of the rafter end. (NOTE 2000: 1.04 to 1.12 times the width of the rafter end.) Therefore, in order to determine whether or not the sun made the shadows of the rafter end it is only necessary to compare relative sizes of the shadow and rafter end images. Referring to Figure A3 we see that for rafter C the ratio is 0.825 mm/ 0.50 mm = 1.65 (using the average between 0.80 and 0.85 mm as the width of the shadow). For rafter B the ratio is 0.55/0.50 = 1.10. Similar measurements using densitometer scans for Photo 2 yield for rafter D (0.55/0.50) = 1.10; for rafter C, (0.70/0.40) = 1.75; and for rafter B, (0.60/0.40) = 1.50. (The comparable data using rafter A and shadow A have not been used since shadow A is at the edge of the garage wall and so part of the shadow may have extended beyond the wall where it could not be registered by the camera. See Fig. A4. ) The average of these ratios is 1.42, which is noticeably larger than the largest expected value of the ratio if the sun were the source. The large variability in the measured ratios, ranging from as low as 1.1 to as high as 1.75 are indicative of the experimental problems with measuring the widths of images as small as those of the rafter ends and of the shadows of the rafter ends. In particular, the contrast between the brightness of the shadows and of the adjacent illuminated wall is so low that photographic noise plays an important role in determining the "edges" of the images of the shadows. Another important factor in determining the locations of edges is the finite aperture ( slit) size of the scanning densitometer, which tends to blur out very fine details. However, after taking these effects into account it seems that the photographic data do indicate a light source larger in horizontal angular extent than the sun. By reversing Equation (A - 9) to find A, and using K = W/s , it is possible to find A using the calculated values of K given above: 

A = 2 ARCTAN (s (K-1)/2(R) ) (A - 12) 

With s = 1.5", R = 10", and K = 1.42 this yields 3.6 degrees, which is much larger than the effective angular size of the sun could ever be. Even the lowest ratio values found, 1.10, correspond to an angular size of about 0.86 deg, which is greater than that of the unobscured sun (0.53 deg). (NOTE 2000: using R = 6 inches with s = 1.5 and K = 1.42 yields about 6 degrees.) 

Other Darkened Areas Under the Eave: Possible Other Shadows 

Besides the very apparent horizontal shadow of the edge of the roof and the shadows of the eave rafters, there are other darkened areas of the board under the eave . These darkened areas are on the right hand sides of rafters D, C and B. They look like what one might expect if there were a somewhat bright source southeast of the garage causing shadows of the ends of the eave rafters to appear on the board just under the eave. This hypothetical "southeast source" would have been less bright and larger in angular size than the source which made the shadows which I have discussed in previous sections of this appendix. On the photos these other "possible shadows" extend to the right for a considerable distance from rafter D and from rafter C, and for only a short distance to the right from rafter B. They are illustrated in Fig. Al. If they are not shadows but "anomalous" darkenings of the board for some other reason, then they just happen to be remarkably consistent with what one might expect if there were a source southeast of the garage as well as a brighter, smaller source roughly east of the garage. Needless to say, if the sun were the main source east of the garage in the morning it seems inconceivable that there could be another source southeast of the garage that could be bright enough to create shadows, even if the sun were partially obscured by a thin cloud. Thus these other darkened areas argue against the sun as the source which was east of the garage. On the other hand, there would be no problem with having two clouds, one south of the other, at sunset causing shadows on the garage. There is one further darkening of a board which appears to be a shadow that would require the source east of the garage to be very narrow indeed, if it is the shadow of the protruding 2 x 4. This darkening runs downward along a vertical board at the corner of the garage (see Fig A1 and the notation "Shadow of 'Protruding Rafter?"). This darkening, although visible in prints and emphasized in the figure, is much fainter than the shadows of the ends of the eave rafters (that is, there is less contrast between the brightness of this darkened area and the illuminated board to its left than there is between the brightness of a shadow of a rafter end and the illuminated board adjacent to it). It seems that the width of this vertical shadow increases with an increase in distance downward along the board. Such an increase would be consistent with a source larger than the sun, but the shadow is so faint that it would be difficult to say just how much wider than the sun. This darkening could also be the shadow, not of the protruding 2 x 4 rafter, but rather of the immediately adjacent vertical board to the right of the shadow that was apparently nailed to the front surface of the garage and therefore blocks all skylight coming from north of (roughly) due east. 


Things may not be what they appear to the "naked eye". Careful analysis of the shadows under the eave suggest that they have characteristics that are incompatible with the sun-shadow hypothesis, but not necessarily incompatible with a hypothesis which includes one or more bright clouds in the sky east (and southeast?) of the wall at sunset. As pointed out in the text of this report, cloud-produced shadows have been observed (and photographed). Hence cloud-produced shadows similar to those on the Trent garage wall are not "physically impossible." 

(NOTE: aerial survey photos obtained after this analysis was completed show that east of the garage wall were a chicken house and a pump house. Each of these buildings would have blocked some of the skylight which could compete with light reflected from a cloud. The less skylight there is the more likely that a bright cloud could cause noticeable shadows.) 


Photogrammetric Estimate of the Location of the Overhead Wires Relative to the Sighting Lines to the UO in Photos 1 and 2 

By estimating or guessing at the dimensions of certain objects which appear in the Trent photos it is possible to reconstruct the relationships between the cameraman and the overhead wires . Once the locations of the wires and of the cameraman are determined, the sighting lines to the UO can be added and it is then possible to estimate the answers to two questions : (a) do the sighting lines cross under the wires, and (b) calling the point where the sighting lines cross SLC, is the ratio of the distances of the camera from SLC in photos I and 2 the same as the ratio of the image sizes in photos I and 2 ? It is the objective of this appendix to present evidence which can answer these questions. The first problem is to locate the camera positions for the two photos. Unfortunately Hartmann did not record any measurements at the time he visited the house, and since both the house and garage are now gone it it is necessary to determine these positions from photographic data alone. Surprisingly, these positions can be determined rather accurately by using the garage wall as a source of data. Specifically, the rafter ends of the garage wall are located as to azimuth angle ( that is, the angle left or right) in the two photos and these angles are projected backward from the rafter ends to the locations of the camera. Further information comes from the known standard size of the largest pipe which protrudes upward from the tank (the filling pipe). Necessary data are as follows: 


Quantity Directions (degrees west of north) 
Center of Photo 26.6 (26.6 deg west of north) 39.30 
deg Direction to UO 25.6 42.9 
Direction to Rafter A (Ra) 41.4 50.1 
Direction to Rafter B (Rb) 43.9 52.6 
" " " C (Rc) 46.8 55.5 
" " " D (Rd) ----- 58.5 

Corner of Main House 5.40 18.9 (NOTE: recalculation in 2000 - 4.5 deg 17.3 deg) 

Estimates Related to the Lower of the Two Overhead Wires Left Side of Picture 

Distance from Lens Axis 23.9 21.9 

Elevation above Horizontal 24.1 19.2 

Brightness Halfwidth* 0.140 mm 0.12 mm 

Middle of Picture: Distance from Lens Axis 11.3 deg 
8.5 deg Elevation above 
Horizontal 22.8 20.00 Brightness 
Half'width 0.144 mm 0.128 mm 

Right Side of Picture: Distance from Lens 
Axis 22.8deg 22.8 deg Elevation above 
Horizontal 24.1 23.0 Brightness 
Halfwidth 0.148 mm 0.138 mm 

Width of the Image of the 0.84+/- 0.05 mm 0.79 
+/-0.02 mm Filling Pipe at the Top of the Tank 

Angle from the Lens Axis to Pipe Image 22 degrees 18 degrees 

*Wire diameter measurements are illustrated in Figure B1. The brightness halfwidth is the image width at one half the maximum brightness variation between the image of the wire and the sky background. (NOTE 2000: the direction of the center of each photo was determined by reference to the direction to the distant white house as identified by Hartmann combined with a geological survey map which showed that house and the Trent farm. Angles, A, to the left and right of the white house were determined by measurements on the photographs and the formula, A = arctan (distance on negative divided by the focal length). The focal length used was 103 mm. Use of the Roamer camera focal length of 100 mm increases the above angles by several percent. For example, the largest angles from center, around 21.6 degrees, the angle increases by about 1/2 degree when the focal length changes from 103 to 100 mm.) 

The photogrammetric reconstruction proceeds as follows: 1.) Choose a spacing for the eave rafters. I chose 2 feet. The actual spacing may have been less, but probably it wasn't greater. The ends of the roof rafters, assumed to be standard "2 x 4" rafters, are 1.5" wide. (NOTE: probably the actual rafters were "2 x 6" but probably not as large as "2 by 8." The vertical dimension of the rafter plays no role in this analysis.) The ratio 24/1.5 = 16 is the same to within experimental error as the ratio of the widths of the images of the ends of the rafters to the spacing between the images of the ends of the rafters, indicating that the-photographic evidence is consistent with the assumption of a 24" spacing. 

2) Assume the garage wall runs due north-south. Actually the direction might be several degrees off, but the Trent house was built next to a road which runs due east-west according to the U.S. Geological Survey Maps (7.5 minute series) . Thus the walls of the house and garage which would have been nearly parallel or perpendicular to the road, probably are close to running due north south or due east-west, depending upon the location of the wall. (NOTE: aerial photos obtained several years after this was written show that the walls of the garage are rotated about 2 degrees counterclockwise (north end toward the west).) The east wall of the garage appears in the photos, according to Hartmann. 

3) Draw the eave rafters two feet apart along a north south line on a scaled map. (See Figure B2; see the scale at the bottom indicating 4 ft. ) Let the eave rafter extend 1 ft beyond the wall. (NOTE: this may be excessive. The distance could be as low as 6 inches.) (NOTE in 2000: during a site visit in May 11, 2000, I found that the east garage wall was covered by a sort of corrugate metal siding which had been placed on top of the 3/4" thick horizontal board siding - shown in Hartmann's site photos of 1967 - which, in turn, was on top of the original boards. The end of the eave rafter was about 5" from the metal siding and therefore about 6" from the original board siding.) 

4) Draw lines from the rafter ends in directions opposite to the directions listed in the above table. For example, for Rafter A in photo I draw a line at azimuth -26.6+ 180 = 153.40; for Rafter A in photo 2 draw a line at azimuth -39.3 + 180 = 140.7 (measured clockwise from due north on the map, with the line starting at the rafter end). The Intersections of the lines locate (approximately) the camera positions from photos 1 and 2. (See Figure B2.) 

5) The filling pipe on the tank appears in both photos. Its image size is directly related to the distance to the camera. Standard filling pipes have outer dimensions of 2.375". Oil tanks are typically 27" wide. Allowing 3" for a spacing between the side of the tank and the garage wall places the filling pipe about (27 + 3)/2 = 15 " from the wall, or about 3" beyond the eave rafters (NOTE: or 9" beyond, if the eave rafters stuck out only 6" from the wall.). To locate the filling pipe in its proper north-south location, proceed as follows: note that the image of the pipe appears just below the image of the shadow of Rc in photo 1. Assuming that the light source is due east of the garage, the shadow would be due west of the end of the rafter. This locates the shadow of Rc on the garage wall. Draw a line from the garage wall just west of Rc (where the shadow is) toward the general location of the camera in photo I , as determined in step 4 above. Now mark a location along this line which is 15" = 1.25' from the garage wall. This locates the (estimated) position of the filling pipe. 

6) The distance from the filling pipe to the camera is given by 

D = {[F/COS(a)]/i} { w/12 } in feet (B-1) 

where F = 103 mm, e is the angle from the axis of the lens to the image of the pipe, and W is the actual pipe width in inches. The COS(e) factor is needed to account for the fact that the effective focal length is not constant over the whole film plane because the film plane is flat (not a constant distance from the center of the camera lens). Using the appropriate values of the quantities i and e from the table, with F = 103 mm yields D = 26.1 ft for photo 1 and D = 27.1 ft. for photo 2. In each case the possible error is +/- 1.5 ft. (NOTE: use of 100 mm as the focal length for a Roamer camera yields distances only 3% smaller: 25.3 ft and 26.3 ft. This is within the likely error in measurements which is approximately 100 x (+/- 1.5 ft/26 ft) = (+/-) 5.7%, or about 6%.) 

7) Draw the distance ranges just calculated from the pipe in the appropriate areas on the map where the sighting lines from the rafter ends cross, thereby further locating the positions of the camera. 

8) As a further check , using data not listed in the table, mark off distances from the corner of the garage according to the fact that the ratio of distances to the corner should be the same as the ratio of the spacings between the images of the cracks between the boards on the garage wall at the corner of the garage. This ratio is about 1.1 after correction for the fact that the corner of the garage wall is somewhat to the left of the center of the lens in each photo (cosine correction mentioned above). Pick one camera position to be "exact" and set the other position 1.1 times farther from the corner of the garage wall. I chose position 1 to be 30 ft from the corner of the wall (26.5 ft from the filling pipe on the tank), and this "forces" position 2 to be 33 ft from the corner and also about 30 ft from the filling pipe. Since this is too far from the filling pipe I have compromised on a distance of 32 ft from the corner, which is 29 ft from the filling pipe, a distance only 1/2 ft greater than the maximum value calculated in step 6. 

9) Place the lower of the two overhead wires on the map by assuming a wire diameter such as 3/16" or 1/8" . Do this by using the image Brightness Halfwidths in the formula given in step 6 to locate the left end, middle, and right end of the wire from the camera positions for photos one and two. The angular "Distances from the Lens Axis" given in the table should be substituted for the angle e in the formula. The formula then gives radial distances from the camera ("slant distances"). To convert to horizontal distances appropriate for plotting on the map, use the angles listed as Elevation above Horizontal in place of b in the following formula 

H = D COS(b). (B-2) 

When the distances have been calculated place marks an the diagram corresponding to the left end, middle, and right end positions for both 3/16 and 1/8 " diameter wires. Note that each photo provides an estimated position. I have drawn average lines through the locations provided by photos 1 and 2 for both 3/16 and 1/8 " diameter wire. 

10) Locate the corner of the Trent house by drawing lines from the camera positions according to the angles given in the table. The above steps yield a diagram similar to that in Figure B2. The final step is to draw in sighting lines from the camera positions according to the data in the table. 

The above steps yield a diagram similar to that in Figure B2. The final step is to draw in sighting lines from the camera positions according to the data in the table. First notice that the sighting lines do not cross under the wire if the wire was not larger than 3/16" diameter. Second, note that the ratio of the distances from the Sighting Line Crossing (SLC) to the camera positions is 

16.25 ft for photo 1 
---------------------------- =0.956 (B - 3) 
17.0 ft for photo 2 

This is to be compared with the ratio of images sizes of the UO: 

UO diameter in photo 2 0.255 mm 
--------------------------------- = ---------------- = 0.873 (B 
- 4) UO diameter in photo 1 0.292 mm 

Note that the size ratio, photo 2/photo 1, should be compared to the inverse of the distance ratio, photo 1/photo 2, because image size is inversely proportional to distance, that is, the image size shrinks as the distance increases. These ratios, although comparable, are not equal. They differ by about 10%. I have tried other map reconstructions starting from other assumed rafter spacings, but the general result has been the same: the sighting lines do not cross under the wires and the ratios are not equal. Since the location of the wires is of critical importance in the reconstruction, it is worth mentioning that Hartmann did take a picture in 1967 which indicated that at that time the north ends of the wires were attached to insulators which were near the peak of the roof of the house. Unfortunately, the distance from the corner of' the house to the peak (measured horizontally) was not recorded. As for the other ends of the wires we only have Mrs. Trent's statement that they went to the "center of the garage." It seems to me unlikely that they attached at the front-back center, i.e., in the middle of the roof, where an attachment could create holes in the roof making it less than watertight. Hence I interpret this as meaning that they went to a post that was sticking up from the center of the garage, but at the rear end. Assuming that the horizontal distance from the corner of the house to the north ends of the wires was about 12 ft and assuming that the wires ran to a post at the peak of the roof at the back of the garage, one can estimate the location of the wires. However, this estimate must be considered highly tentative, especially since there are no data on the exact location of the southern ends of the wires. Nevertheless, it does seem consistent with the estimated wire location if the wires were 3/16 inch thick. One further comment about the wires is in order. Clearly if the wires were as large as 1/4" diameter they would pass essentially (or exactly) over the SLC point. However, it is highly unlikely that wires as large as 1/4" diameter would have been used because of the cost . The purpose of the wires was only to power a light bulb of a 100 watts or so. Useable wires would have been as small as 1/8" diameter, which is standard for house wiring. Such wire is also stiff enough to hold kinks ( kinks in the wires when the photos were taken were still in the wires when Hartmann visited the former Trent farm 17 years later.) 


The lack of data makes it necessary to reconstruct the scene of the photos using photogrammetric techniques combined with estimated sizes of objects shown in the photos. This method introduces considerable uncertainty into the reconstruction. The uncertainty is sufficiently great that a rather wide range of answers to the two questions posed at the beginning of this appendix can be obtained. However, reasonable reconstructions without any "forcing" of the available photographic data and size estimates indicates that the sighting lines did not cross under the wires and that the ratios are not equal. As pointed out in the text, these results, even if perfectly accurate, would not prove the sighting was not a hoax. On the other hand, these results, if reasonably accurate, do not prove that the sighting was a hoax. 


Since this paper was completed in the fall of 1981 for presentation at the Second UFO Conference of the Center for UFO Studies, some new and valuable information about the layout of the Trent farm has been obtained from the Agriculture Survey Department. The Aerial Photography Field Office (Box 30010 , Salt Lake City, Utah 84130) located two photos that had been taken in the time frame of interest. The first picture is dated 7/2/48 (DFQ Roll 4ED,exposure 93) and the second is dated 5/15/56 (DFQ Roll 1P, exposure 88). These were taken from aircraft that flew over the area but not directly over the Trent farm. The scale of both photos was 1:22222 (1" = 1851' ; see Fig. ADD84A). Both photos show the same buildings at the Trent farm but the 1948 photo is clearer (better focused?) so I have concentrated my measurement effort on the first photo. The Aerial Photography Office sent me a print of the original aerial photo and a five power blowup. (Actually it is a 5.045 power blowup with a scale 1" = 367', as determined by comparing the spacings of identifiable objects with the spacings given on the geological survey map ). I used photographic magnification to create prints at a scale as large as 1" = 107'. I scaled the print of the original using a U.S. Geological Survey map. I then measured the separations of the images of the buildings on the blowups. The estimated accuracy of measurement is about one foot (plus or minus). The accuracy is limited by the slight fuzziness of the edges of the magnified images. (NOTE 2000: on May 11, 2000 I visited the site of the Trent farm. The house burned down some 40 years ago and was replaced by a single-wide trailer. Then about 20 years ago the present owners replaced that with a double wide trailer. The original base for the Trent house partially used under the trailer which does not align with the original house. However, the present resident had a good idea of where the southwest corner of the original house was, based on the present cement foundation. There is a pump house, which is no longer used as a pump house (used as a laundry), which lies on a cement slab and is made of cement blocks. It probably is the original pump house. There have been rather large additions to the original garage. However, the north, east and south walls are still there, albeit with nice wood siding on the original wood walls. As a check on the scaling of the magnified aerial photo I measured the distance from the garage to the center of the present road. Starting at the north edge of the original garage wall the distance along the driveway to the center of the east-west road is about 109 ft. The edge of the roof extends about 1 foot beyond the wall. Therefore from the edge of the roof to the center of the road is about 108 ft. On the blowup photo, with the estimated scale of 1" = 107 ft, the distance from the image of the edge of the garage roof to the center of the road is 1." Hence to within a foot or so the scaling I did years ago was accurate.) These data allowed me to create a diagram or "map" of the back yard as shown in the illustration (Fig. ADD84B). I was pleased to find that the scaling which I had done several years before, using only the original UFO photos plus some educated guesses, was very close to correct. For example, in the previous reconstruction I had estimated the distances of 18 ft between the house and garage The aerial photo indicates a distance of 17-19 ft. The distance in the new reconstruction is set at 18 ft. (NOTE 2000: based on the present occupant's best guess, the southwest corner of the original house was about 17 ft east of the northeast corner of the garage. The north wall of the present "pump house" is 2 ft north of the north end of the garage. Assuming that the present pump house is the building identified by Mrs. Trent as the pump house shown in the aerial survey, then the south wall of the main house was north of the north wall of the pump house and hence at least 2 ft north and perhaps as much as 4 ft north of the north end of the garage.) The identifications of the various buildings other than the house and garage were provided by Mrs. Trent in a number of conversations, including the most recent (Dec. 9, 1982) after I sent her copes of the blowups (and copy negatives and prints of her original photos). The diagram shows the locations at which Mr. Trent was standing are illustrated along with the location of the overhead wires as determined by a photo taken by Hartmann in 1967 and by descriptions provided by Mrs. Trent. Hartmann's photo shows the wires attached to insulators near the peak of the house roof. The other end of the wires, according to Mrs. Trent, went to the "middle" of the garage which, I assume, means the middle of the rear end of the garage. Hartmann's photo confirms that the wires ran toward the back of the garage, but it does not show here they were attached. According to Mrs. Trent her (and, through her, according to Paul) the wires provided power for a light bulb in the garage. Since the wires were not heavy and were not carrying much power it may be that they were attached to a board (2 x 4 or 2 x 6) which stuck up from the back of the garage at the peak of the roof. I have seen an arrangement of that type myself in rural settings. It is assumed in this reconstruction that the wires did actually attach to a point at the center of the back of the garage. (NOTE 2000: I examined the rear end of the garage carefully for evidence of a structure that could have supported the wires. There is no such structure at present, but then, the wires are not present either, having been removed some 40 years ago when te house burned down and before the siding was added to the walls. I was too far from the peak of the rear wall of the garage to determine whether or not there were nail holes in the eave rafters indicating that at some time there had been something attached to the wall. There still is an outdoor light fixture attached to the front end of the original garage which looks exactly like the light fixture that was attached to the rear of the house, as shown in Hartmann's photo. This may be the light to which Mrs. Trent referred. There may have also been a light inside the garage, but "modern" paneling in the garage has covered up any evidence there might be of the original electrical wiring. ) One of the important "successes" of my original photogrammetric reconstruction was a "prediction" that the garage was unexpectedly long, perhaps more than 25 ft long from front (north) to back (south). This prediction was confirmed by the aerial photos which indicate the garage was a least 25 ft and perhaps about 28 ft long. (NOTE 2000: the garage walls form a rectangle 18 ft wide by 24 ft long. The roof overhang adds about a foot at each end and 1/2 ft at each side, making the roof dimensions, as seen from above, about 19 ft by 26 ft.) The major reason for undertaking the original reconstruction of the back yard was to determine whether or not the overhead wires passed over the sighting line crossover point (SLCP) (as described in Appendix B). The new reconstruction of the back yard combined with the previously determined sighting directions shows that the SLCP was about 4 ft northwest of the overhead wires, which is reasonably close to the original reconstruction which indicated 5.5 ft if the wires were 3/16" in diameter. The decrease from 5.5 ft to 4 ft resulted from better scaling and from a decrease in the distance from the corner of the house to the point where the wires were fastened to the house. I had initially estimated that the distance was 12 ft, corresponding to a house width of 24 ft using a photo supplied by Hartmann. However, the aerial photos suggest that the house width was only 22 ft so I have adjusted the scaled map accordingly. The aerial photos confirm that the farmhouse of Mr. Trent's father was 440 ft west of Mr. Trent's house. Furthermore, they confirm that there were no obstructions between the houses so that it would have been possible for Mr. and Mrs. Trent to see Trent's father on the back porch and yell to him before the object disappeared in the west. (I thank Brad Sparks for initially suggesting aerial survey photos and Philip J. Klass for suggesting that I write for Agriculture department aerial photos.) 


As I pointed out in the discussion at the end of the main text of this paper, the photos tend to be equivocal on the hoax hypothesis because one could imagine a way in which they could have been hoaxed and perhaps the Trents could have hoaxed them with some effort and a lot of "luck." (Luck: they hung a small model which just happened to diffuse light coming from the sky above in such a way that the bottom became a nearly uniform source of light; this "luck" requires that the model be constructed from translucent material rather than a simple "hang a pie pan" approach; more luck - they suspended the model with a thread that was very thin or else the thread happened to match the color of the sky background.) If they were lucky in making a model, then their good luck was partly offset by bad luck: they allowed the photos to show the overhead wire from which the model was hung. Because the photos are not completely definitive the argument over the truth of their story must be based in large part upon their own testimony given to reporters, investigators and friends over the years. In evaluating the testimony skeptics have emphasized the differences between the reported versions of the sighting. In particular, they have pointed to differences between initial newspaper accounts as well as differences between initial and later accounts. These differences are cited as evidence that the Trents really did not witness the event they have described and are therefore reporting a hoax story which they made up but forgot to "coordinate" with each other. On the other hand, if the Trents' reports had been 100% identical these these same skeptics would point to the complete correlation as evidence of a hoax because witnesses generally don't see the same event in the same way and no one remembers everything exactly as it happened. It is my opinion that the slight differences in the reports of the original sighting can be attributed to the fact that the Trents were interviewed after about a month had passed and that the more detailed interviews (reported after the original Telephone Register article) were done separately, for example, with Mrs. Trent at home and Mr. Trent where he worked. Two people never give completely identical reports of the same event. Therefore it is not surprising that the reports would differ. A further source of difference in the published reports lies in the fact that reporters usually do not report exactly what they were told by a witness. (Even quoted statements are not always correct.) A reporter generally publishes his or her interpretation of what the witness had said. The interpretation which might not accurately portray what the witness was trying to describe. Finally, a newspaper story is usually edited to make it read smoothly and to fit within a certain space. This editing may further change the report by leaving out or modifying the statements by the witness. Thus, given the fact that the Trents' memory of the exact event would be "faded" during the month before they were interviewed, given the tendency or reporters to write their interpretations of what the witness has said and given the tendency of newspapers to edit stories, it is remarkable that there is a considerable consistency between published versions of their report. Besides the consistency in the versions of the sighting itself, there is a further factor which must be taken into account if one is to decide whether or not the photos are a hoax. That factor relates to the Trents themselves: would they be capable of or likely to create such a hoax? In the text of this paper I have already listed a number of people who have interviewed the Trents and concluded that it was unlikely that they hoaxed the pictures. The reason generally given that they did not hoax the pictures is that they were basically honest people. This opinion was stated by the newspaper people who were first involved with the story and by the banker (Wortmann) at the time that the photos were published and again many years later. Other people who had talked to the Trents gained the same impression (including William Hartmann). As I conversed by phone or by letter with these people who had actually met the Trents I detected an undercurrent of opinion which went beyond simply saying they were honest people. However I did not mention that undercurrent in the main text of this paper because its importance did not become clear to me until very recently (May, 1984) when I had the good fortune to be in touch with a farm family that had been neighbors of the Trents since they moved to Dayton, Oregon, in the 1950's. These people stated that they could not remember either Mr. or Mrs. Trent ever mentioning the photos. The opinion which I received from talking with them reinforced what I had suspected from my earlier information: Paul and Evelyn are not mentally capable of thinking of producing a hoax for any reason, and even if the thought did cross their minds they would not be likely to carry it out since it would require extra work that would not relate to any of their familiar daily activities. When I talked on the phone with Mrs. Trent I found that a large portion of the time was taken up in discussions of recent daily events and family matters (i.e., things that had happened in the days or weeks before my phone calls), even though I repeatedly tried to direct the conversation to the subject of my interest. I concluded that the UFO pictures were definitely not the most important event in their lives. Instead, they were more of an annoyance to be ignored as much as possible. My opinion was supported very strongly by the neighbors. As I discussed the Trents with their neighbors I was reminded of a statement by Bill Powell, the reporter who first interviewed them, I asked if he thought the Trents could have hoaxed the photos and his blunt answer was essentially that they were not mentally capable of producing a hoax. In a similar vein, Arthur Fryer, the retired science teacher who visited the Trents at my request, when asked about the possibility of a hoax, said, "I can't believe that these people would have the mental capacity to figure ways of fooling anybody. I really think a photo of Paul would be quite convincing." The "discovery" that the Trents really didn't have the intelligence necessary to conceive and carry out hoax of any kind provides further evidence that they were telling the truth. I would suggest that any skeptic who is serious about disproving the Trents' report must do more than search for small discrepancies between newspaper stories. The skeptic must obtain opinions from people preferably professionals, who knew the Trents well as to whether or not a hoax is consistent with the life history of the Trents. If the photos were hoaxed these opinions should show conclusively that the Trents have the mental capacity and the will to produce a hoax if they so desired. Without such opinions it is useless to continue the discussion of how the hoax was carried off and how the Trents managed to convince so many people. 


In closing I would like to point out that further research could be done on this case, although I don't intend to continue. One could search through local newspapers to locate all of the news stories that were written in the weeks after the publication of the photos. According to an article in the McMinnville newspaper, on June 15, 1950, the Trents were "besieged with reporters and cameramen." The stories written by all these reporters must reside somewhere in newspaper archives. Besides doing historical research, it would also be valuable to interview a number of people who have known the Trents for years in order to compile their life history. Because of the results of my own considerable efforts I would be greatly surprised if further historical research or further studies of the Trents produced any information that is noticeably different from what I already have. However, if someone should undertake such a study I would be interested in knowing the results. 


Since the preceding text, appendices and Addendum were written the Trents' life history was completed. They died in 1997 (Evelyn) and 1998 (Paul) (see obituary notices below). There was no other large investigation of their sighting and I did no work on the case following 1984, until 1999. At that time a re-investigation was initiated by Brad Sparks and David Rudiak. As part of the reinvestigation that started in 1999 I wrote a computer program to make a mathematical model of the Trents' back yard. I did this in order to speed up the process of determining, for various assumed values of the "parameters" (see below) of the sighting, whether or not the wires passed over the sighting line crossover point (SLCP) and whether or not the ratio of the UO image sizes equaled the inverse ratio of the distances of the camera locations from the SLCP. (Until I developed this program it was necessary to draw a new, carefully dimensioned diagram each time parameter values were changed.) One assumption in this program is that the wires ran from the center of the house near the peak of the roof to a post at the center of the rear of the garage. The calculation is based on the following "parameter values:" the sighting directions to the UO relative to true north, the directions to the corner of the house and the corner of the garage, the measured widths of the UO images, the width of the house, the length and width of the garage, the spacing between the garage and the house and the north-south offset (if any) of the front of the garage relative to the rear of the house. The program then calculates the locations of the camera, the location of the SLCP, the (horizontal) distance from the SLCP to the overhead wires and the ratios mentioned above. This program is contained in Appendix C. As the re-investigation continued it was determined through the joint efforts of Brad Sparks, Terry Halstead, David Silver (President of the International Photographic Historical Society) and Joel Carpenter that the camera was not a Kodak, as originally supposed, but rather a Roamer 1 built by the Universal Camera Corporation. The focal length for this type of camera was about 100 mm. (The minimum f-stop was 11 and the shutter was fixed at about 1/50 second.) Hence all of the angles which I had calculated based on the 103 mm focal length for a Kodak camera had to be recomputed. However, it was found that the computer program gives essentially the same results, namely that the inverse distance ratio mentioned above is about 1.01 to 1.02, while the UFO image ratio is 1.145, and the (horizontal) distance from the SLC to the wires is 3 to 4 ft if the wires attached to a post at the center of the rear of the garage. 


In 1957 two magazines, the Flying Saucer Review and the Royal Air Force Flying Review both published a photograph that was said to have been taken by a French military pilot. These publications are illustrated in the files labeled TrntRouenFSR.jpg and TrntRouenRAFFR.gif. The text of neither publication discussed the photo and the only information is contained within the photo caption. At my request Claude Poher, formerly of the French National Space Agency (CNES), tried to locate the presumably French military source for the photo. At the same time I contacted the publishers of both the magazines. This was done in the 1976-1977 time frame, 20 years after the photo was published. In both cases the search ended in failure to locate the original source. About all that can be said about the image in the photo is that it is clearly the same sort of object as appears in the Trent photo #2 but it is not simply a "rephotograph" of the Trent photo because the orientation in 3-D space is different, i.e., the object in the Rouen photo is rotated somewhat from the orientation in Trent #2. If the story behind the photo is correct, that it was taken by a French miliary pilot, then if provides strong corroboration for the Trent photos. Unfortunately we will probably never know whether or not the Rouen photo is actually what it purports to be, 


In 1995 I was contacted by Terry Halstead who wanted to make a video documentary of the Trent sighting to use as part of a large UO documentary. I provided him with copies of my work and suggested lines of investigation for him to use. We are fortunate that he managed to obtain a videotaped interview with the Trents. This was probably the first extensive interview in 30 years (the previous being by Veikko Itkonen in 1969, which was never shown in the USA, so far as I know). During this interview Evelyn, who did most of the talking because Paul was having difficulty talking, repeated what I had heard her say numerous times 20 year before about the events of the sighting, the description of the object (she never called it a flying saucer) and so on. Paul contributed a few comments during the interview to support what Evelyn said. Two years later Evelyn died. The obituary in the McMinnville News-Register of Aug. 7, 1997 reads as follows: 


Services for Evelyn Mae Trent of McMinnville will be held at 11 a.m. Friday in the chapel of Macy & Son Funeral Directors, with the Rev. Kyle French of Dayton Christian Church officiating. Interment will be in Evergreen Memorial Park, McMinnville. The funeral home will be open for viewing until 7 p.m. today and from 8 to 11 a.m. Friday. Mrs.Trent died Aug. 4, 1997, in Columbia Willamette Valley Medical Center, McMinnville. She was 71. She was born Jan. 1, 1926, in Wheeler, the daughter of Jessie Clifford and Mabel A. Page Eades. She moved to Buell at an early age. She and Paul Trent were married on March 6, 1943. After marrying, the couple moved to Cloverdale, where they owned and operated a dairy farm. They moved in 1958 to their farm in Dayton, where they raised corn, berries and grain. Mrs. Trent had lived in McMinnville since 1987. She enjoyed canning and crocheting and loved spending time with her family. Survivors include her husband; four sons, Larry Trent of Dayton, Arthur Trent of Dundee, Thomas Trent of Newberg and Jerry Trent of Roseburg; two daughters, Linda Sayler and Tammy Gochenour, both of Dayton; three brothers, Thomas Eades of Salem, Buster Eades of Portland and John Eades of Seleth, Wash.; a sister Betty, of Dallas; 17 grandchildren and six great grandchildren. She was preceded in death by two brothers, Virgil Eades and Vernon Eades and a sister, Mary Orr. Memorial contributions may be made to the American Diabetes Association or the American Heart Association, in care of Macy & Son Funeral Directors, 135 N. Evans St., McMinnville, Ore. 97128. 

About six months later Paul died. His obituary in the News-Register of February 17, 1998 reads: 

Paul A. Trent 1917-1998 

Services for Paul Arthur Trent of McMinnville will be held at 11 a.m. Wednesday in the chapel of Macy & Son Funeral Directors. The Rev. Kyle French of Dayton Christian Church will officiate. Interment will be in Evergreen Memorial Park, McMinnville. The funeral home will be open for viewing from 3 to 7 p.m. today. Mr. Trent died Feb. 13, 1998, in Life Care Center, McMinnville. He was 80. He was born Feb. 28, 1917, in McMinnville, the son of John and Alice Bowers Trent. He was raised and schooled in McMinnville and Buell. He and Evelyn Eades were married on March 6, 1943. He moved in 1958 to a farm in Dayton area and raised corn, berries and grain. He had lived in McMinnville since 1987. He enjoyed country music and the Oregon Coast. Survivors include two daughters, Linda Sayler and Tammy Gochenour, both of Dayton; four sons, Larry Trent of Dayton, Arthur Trent of Dundee, Tommy Lee Trent of Newberg and Jerry Trent of Roseburg; a brother, Clayton Trent of Dayton; 17 grandchildren; and six great-grandchildren. He was preceded in death by his wife in 1997; and by a brother, Everett Trent and a sister Mae Shelburn. Memorial contributions may be made to the Paul Trent Memorial Fund in care of Macy and Son Funeral Directors, 135 N. Evans St. McMinnville, Ore. 97128. 

Several years before the death of Evelyn I was told that a rumor going around at that time was that Paul Trent had confessed to the hoax just before he died. I checked up on this rumor by calling the Trents. Evelyn answered the phone. I asked if I could speak to Paul and she said what she had told me some 20 years before, "he doesn't like to talk on the phone because he has a hearing aid." One rumor quashed! The skeptics have claimed that the UFO sighting was the most important thing to have happened in their lives. Skeptics wanted to believe that because It would explain (to the skeptics) why the Trents would continue to maintain the supposed hoax in the face of all the criticism they received. From this point of view, then, it must be considered ironic that the "most important event in their lives," the event which made the Trents internationally famous, was not even mentioned in either obituary. The lives of the witnesses are over, but the saga of their photos lives on. 


' This is the TrentYyard Program to determine the location the sighting line crossing point (SLCP) and its location relative to the overhead wires 'as a function of the following parameter values: '(a) location of the house relative to the garage, (b) the 'width of the house, (c) the north-south offset (if any) of the south wall 'of the house relative to the north end of the garage wall '(d) the width of the garage and (e) the location of the 'attachment of the electric wires to the garage. 'Of course all the sighting directions are also built into the program 'and can b adjusted within the program itself. The preceding parameter values 'are variables that are entered as the program runs. 

'The origin of coordinates is at the northeast corner of the garage wall. 'East is Positive X. South is Positive Y. 'From Hartmann's photo we know that the north end of the power wires were 'attached at the center of the south wall of the house. The X value of 'this attachment point is 1/2 the house width plus the X distance from the 'garage corner to the house corner. The Y location of the attachment point is 'the north-south offset of the south wall of the house relative to the 'north end of the garage. 

'It is assumed that the other ends of the wires were attached to a board 'that stuck up from the center of the rear of the garage. 'The X-Y coordinates of this board relative to the coordinate 'origin at the northeast corner of the garage are determined by the length 'and width of the garage (Xboard = 1/2 width of garage; Yboard = length of 'garage). If the wires were NOT attached to a board rising up from the 'center of the rear but from some other point then shrink or expand the 'garage length and width appropriately to make the coordinate of 'attachment point be at the desired X-Y position. ' 'IN the following program the location of the camera is determined by the 'angles or lines of sight from the camera to the corner of the garage 'and to the corner of the house and by the actual assumed positions of 'these corners. Hence if the locations of the corners are fixed at some 'chosen values and other parameters are varied the X-Y positions of the 'camera will not change, nor will the location of the SLCP. The positions where 'the wires cross over the sighting lines will change if the garage length, 'garage width and house width are changed even if the corner positions are 'fixed. 

UO1 = .292: 'measured width on negative of UO image in photo 1, in cm UO2 = .255: 
'width of UO image in cm photo 2 RAD = 3.14159 / 180: 'degrees to radians conversion 'The following angles are with respect to the Geological Survey Map 'and based on the aerial survey photos which suggests that the house and 'garage east and west walls were 2.5 degrees away from pointing due 'north south; 2.5 rotated clockwise 'Angles WITH RESPECT TO NORTH, rotating counterclockwise; these can be 'changed if necessary: T11 = 4.5 + 2.5: ' angle from camera to corner of house in photo 1 T12 = 41.5 + 2.5: 'angle from camera to rafter A at corner of garage in photo 1 T21 = 17.3 + 2.5: 'angle from camera to corner of house in Photo 2 T22 = 50.6 + 2.5: 'angle from camera to Rafter A, Photo 2 PHI1 = RAD * (25.6 + 2.5): 'sighting line to UO in photo 1; angle w.r.t. north PHI2 = RAD * (42.9 + 2.5): 'sighting line to UO in photo 2;angle w,r,t, north INPUT "Enter the width of the house in feet, e.g., 22 "; HW INPUT "Enter the length of the garage in feet, e.g., 28 "; GL INPUT "Enter the width of the garage in feet, e.g., 17 "; GW INPUT "Enter the assumed east-west separation between the house and garage "; S PRINT "Enter the assumed north-south offset distance between the south wall " PRINT "of the house and the north end of the garage" INPUT "with a NEGATIVE sign if the house is NORTH of the garage "; of1 of = -of1: 'change sign to work in formulas below E = ATN(of / S): 'E is angle in radians away from due east-west if the rear house 'wall is north or south of the northeast corner of the garage; positive northward DS = (S ^ 2 + of ^ 2) ^ .5: ' the distance between the corner of the garage and 'the southwest corner of the house B1 = DS * COS(RAD * T11 - E) / SIN(RAD * (T12 - T11)): 'distance from camera 1 'position to corner of garage; use law of sines with sin(90+ t11-E) = cos(t11-E) B2 = DS * COS(RAD * T21 - E) / SIN(RAD * (T22 - T21)): 'distance from camera 2 'position to corner of garage 'X AND Y POSITIONS OF CAMERA RELATIVE TO CORNER OF GARAGE AS ORIGIN 'X is positive east (right), Y is positive south (down) X1 = B1 * SIN(RAD * T12): Y1 = B1 * COS(RAD * T12): 'camera in photo 1 X2 = B2 * SIN(RAD * T22): Y2 = B2 * COS(RAD * T22): ' camera in photo 2 PHI4 = ATN((Y1 - Y2) / (X2 - X1)): ' this is the angle measured clockwise from due 'east of the line, L, that connects the two camera positions L = (Y1 - Y2) / SIN(PHI4): ' this is the distance between camera positions DELTAPHI = PHI2 - PHI1: ' the angle between the sighting lines 'Now use the law of sines to locate the sighting line crossover point (SLCP) c = L * COS(PHI4 - PHI2) / SIN(DELTAPHI): ' distance from camera 1 to SLCP d = L * COS(PHI1 - PHI4) / SIN(DELTAPHI): 'distance from camera 2 to SLCP XC = X1 - c * SIN(PHI1): ' x position of SLCP YC = Y1 - c * COS(PHI1): ' y position of SLCP 'Now calculate distance from the SLCP to the 'wires running from the center of the rear of 'the house to the center of the rear of the garage K = ((GW / 2 + XC) ^ 2 + (GL - YC) ^ 2) ^ .5: 'distance from crossover 'point to the center of garage where wires were attached DELTA1 = ATN((GL - YC) / (XC - (-GW / 2))): 'This is the clockwise 'angle between due east and a line from the center of the garage rear 'to the SLCP; note that GW is at negative x DELTA3 = ATN((GL - of) / (GW / 2 + S + HW / 2)): 'this is the clockwise 'angle relative to east of the wires running from the center of rear 'of the garage to the center of the rear of the house DELTA2 = DELTA1 - DELTA3: ' the thin angle between a line from the rear 'of the garage to the sighting line crossover and another line from the 'rear to the center of th back of the house. 'Now note that K is the length of one side of a triangle which can 'be used in the law of sines with appropriate other angles to get the 'distance from the SLCP H1 = K * SIN(DELTA2) / COS(DELTA3 - PHI1): ' distance from wires to SLCP 'as measured along sighting line 1 H2 = K * SIN(DELTA2) / COS(DELTA3 - PHI2): ' distance from wires to SLCP 'as measured along sighting line 2 DIST1 = c - H1: ' distance from camera 1 to wires DIST2 = d - H2: ' distance from camera 2 to wires LPRINT LPRINT LPRINT "Trent Yard Program of March, 1999; modified May, 2000" LPRINT " The following angles are with respect to the alignment of the " LPRINT " sides of the house and garage, which, in turn, are assumed to run" LPRINT " 2.5 degrees east of true north." LPRINT "In what follows all angles are degrees and distances are feet unless" LPRINT "otherwise noted." LPRINT LPRINT "The corner of the house in 1 and 2 is at angles "; T11; " and "; T12; "." LPRINT "The end of rafter A in 1 and 2 is at angles "; T21; " and "; T22; "," LPRINT "The sighting lines in 1 and 2 are "; PHI1 / RAD; " and "; PHI2 / RAD; "." LPRINT "The house width is "; HW; " and the garage width is "; GW; " ft." LPRINT "The garage length is "; GL; "." LPRINT "The UO image sizes are "; UO1; " cm in photo 1 and "; UO2; " cm in photo 2." LPRINT LPRINT "For house-garage separation "; S; " ft and offset = "; of1; " ft we have" LPRINT "the camera position 1 at X1 = "; X1; ", Y1 = "; Y1; " ft" LPRINT "and the camera position 2 at X2 = "; X2; " Y2 = "; Y2; " ft." LPRINT "The distance between the camera positions is "; L; " ft." LPRINT "The X position of the Sighting Line Crossover Point (SLCP) is "; XC; "." LPRINT "The Y position of the SLCP is "; YC; "." LPRINT "The distance from camera position 1 to the SLCP is "; c; "." LPRINT "The distance from camera position 2 to the SLCP is "; d; "." LPRINT "IF THE UO were simply hanging beneath the SLCP" LPRINT " the UO image size ratio would be equal to the inverse of the distance ratio" LPRINT " which is "; d; " / "; c; " = "; d / c; ". Actually the ratio UO1/UO2" LPRINT " is equal to "; UO1 / UO2 LPRINT LPRINT "The distance from the SLCP to the wires measured along sighting line 1" LPRINT " is "; H1; " and the distance from the SLCP to the wires measured along " LPRINT " sighting line 2 is "; H2; "." LPRINT LPRINT "The distance from the wires to camera position 1 is "; DIST1; " and the" LPRINT "distance from the wires to camera position 2 is "; DIST2; "." LPRINT " If the UO were simply slid along the wire to a position along sighting" LPRINT "line 2 after being at a position under the wire but along sighting line" LPRINT "1, then the distance ratio would be "; DIST2 / DIST1; " which can be " LPRINT " compared with the inverse image size ratio, "; UO1 / UO2; "." 

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