To echo Hartmann, the simplest interpretation
of these photos is that they, indeed, show a distant object.
However, simplicity does not necessarily imply truth. ·Further
research will be necessary to resolve this case "once and
NOTE: APPENDIX A provides further data and analysis regarding
the brightness of a white vertical surface and also provides
data to support the veiling glare analysis presented in the text.
The following images also provide further information:
Blbliography and Footnotes
1. Scientific Study of Unidentified Flying Objects, E.U. Condon, Ed. (Bantam, 1969, pg. 396)
2. P.J. Klass, UFO's Explained, Random House, New York (1974)
3. R. Sheaffer, private communication
4. C. Grover, private communication (Grover was a Navy professional photographer)
5. Note that the range increases with assumed darkness of the bottom of the UO. If the bottom were black, B(r,O) = 0, the range would be about 2.4 km with gamma = 0.6·
6. Handbook of Chemistry and Physics, Forty-first Edition, (Chemical Rubber Publishing Company, Cleveland, Ohio 1960)
7. Measurements have been made of the brightnesses of the
bottoms of several model UO's made of uniformly translucent materials.
The models were oriented with respect to the sun in the
same way as it would have been if the UO in photo 1 were a model
lit by the morning sun. The brightness of the bottom of each
model was measured as a function of position, with the "front"
part being that part closest to the sun (in photo 1 the front
part of the elliptical image is at the right hand side). The
front part of the bottom was found to be from 20% to 40% brighter
than the back part for each model. However, the brightness
variation of the image of the bottom of the UO in photo 1 is
only (+/-)5% with the back somewhat brighter than the front.
These experiments, and the comparison with the image of
the UO, suggest that if the UO were a nearby model it was not
made of a uniformly translucent material.
8. W. Spaulding, GSW Inc., Phoenix, Arizona, private communication.
An electron microscope test of the negatives has shown
that the grain structure is consistent with that of known Verichrome
film, but not with Plus X.
9. However, experiments (e.g. R. S. Laurcnce and J. W.
Strohbehn, "A Survey of Clear Air Propagation Effects Relevant
to Optical Communications," Proc. IEEE 58, 1523 (1970))have
shown that there is a period of time just after sunrise when
the turbulence is quite low. The pictures may have been
taken during this period. If this were so, even a very
small amount of atmospheric edge distortion would correspond
to a rather large distance to the object.
10. I thank Charles Grover, William Hartmann, and Robert
Sheaffer for instructive comments on earlier versions of this
paper. I also thank NICAP for free access to their files
and for assistance in obtaining the negatives.
11. Note added in proof: the fog density of the negatives
is consistent with the range of values expected when gamma =
0.5 to 0.6, but is larger than expected when gamma = 0.3. The
brightness of the illuminated part of.the distant white wall
and the brightness of the shaded part of the same wall have been
calculated for gamma = 0.3, 0.4, and O.6. The calculated
brightness ratios, (illuminated/shaded), are, respectively, 10(+/-)2,
3(+/-)0.5, and 2(+/-)0.2. A field measurement of the same
ratio under conditions similar to those when the pictures were
taken yielded 1.5 to 2. Thus both the fog density measurement
and this brightness ratio measurement indicate that gamma is
greater than 0.3 and perhaps even greater than 0.6.
a) Experiments with a Kodak Vigilant lens of 153 mm focal length
yielded the same or lower values of veiling glare than assumed
in this paper.
b) Shadows on a surface that faces the east when the sun was
in the west have been observed when a cumulous cloud was in the
sky to the east of the surface.
NOTE 1 ADDED IN APRIL, 2000: A larger paper in which I
discussed the "rest of the story", including cloud
shadows and verbal testimony, was presented at the second conference
of the Center for UFO Studies which occurred in 1981.
That paper was eventually published by the Center in the Spectrum
of UFO Research in 1988. See "The McMinnville Photos,"
the companion paper to this one.
NOTE 2 ADDED IN APRIL, 2000: A very recent re-investigation
of the Trent sighting (ca. 1999) has demonstrated that the camera
used was probably not a Kodak type but rather a "Roamer
1" built by Universal Camera Corp. of New York for several
year starting in 1948. It was a very inexpensive camera
with a minimum f stop of f/11 and a fixed shutter time of 1/50
sec. The focal length was rated at 100 mm. The camera
was designed to be held in the "landscape" orientation
(long dimension horizontal) and the direction finder was to be
viewed from above, that is, the the operator held the camera
at stomach or chest level and looked downward into the viewfinder
to point the camera at the scene before taking the photo. The
fact that the focal length of the camera was 100 mm rather than
the 103 mm assumed here has no effect on the photometric calculations
in this paper. Use of this shorter focal length does make
the calculated size of the UO 3% larger, e.g., in Table IV all
the diameters and thicknesses should be multiplied by 1.03.
I thank Brad Sparks, Joel Carpenter and David Silver (President
of the International Photographic Historical Association) for
successfully identifying the camera that was actually used.