projector. 
ramic Camera 
c Work.” Am. 
1. 38, pp. 482- 
the Panoramic 
veying,” U. S. 
7. 
> Surveying of 
ips of the Fed- 
Jse of Aerial 
ic Mapping,” 
ircular (Avia- 
h 10, 1921. 
er E. A, Jr, 
ition of the 
"OU. S. Geol. 
jc Phototopo- 
of Am. Geog- 
0, Vol. 30, no. 
ic Instructions 
ey, EI. S. Geol. 
F. H., "Aerial 
Southeastern 
Bulletin 797-E, 
tiplex Stretches 
ngineering, vol. 
—404. 
erald, Gerald, 
ice of the Pho- 
TOGRAMMETRIC 
  
PHOTOGRAMMETRIC ENGINEERING 13 
ENGINEERING, January-March 1944, vol. 
X, no. 1, pp. 16-19. 
10. Altenhofen, R. E., “Accuracy and Adapt- 
ability of Stereoplotting Instruments as 
Revealed by U.S. Geological Survey Prac- 
tice,” PHOTOGRAMMETRIC ENGINEERING, 
June 1951, vol. XVII, no. 3, pp. 370-375. 
11. Kelsh, H. T., “The Kelsh Plotter,” PHo- 
TOGRAMMETRIC ENGINEERING, March 1947, 
vol. XIII, no. 1, pp. 121-126. 
12. Davey, C. H., “Current Research in 
Mapping Techniques by the Geological Sur- 
vey,” PHOTOGRAMMETRIC ENGINEERING, 
March 1949, vol. XV, no. 1, pp. 108-113. 
13. Whitmore, G. D., Advanced Surveying and 
Mapping, International Textbook Co., 
1949. 
14. Wilson, R. M., “A New Photoalidade,” 
Military Engineer, vol. 29, no. 68, pp. 434— 
436, November, December, 1937. 
15. Buckmaster, J. L., “The Camera Lucida 
for Aero-Mapping, PHOTOGRAMMETRIC EN- 
GINEERING, June 1946, vol. XII, no. 2, 
pp. 235-245. 
16. Davidson, J. I. and Buckmaster, J. L., 
“The Geological Survey Radial Intersec- 
tor," - PHOTOGRAMMETRIC ENGINEERING, 
1942, vol. VIII, no. 4, pp. 229-245. 
17. Lewis, J. G., “Mechanical Instruments for 
Plotting from Oblique Photographs,” PHo- 
TOGRAMMETRIC ENGINEERING, December 
1945, vol. XI, no. 4, pp. 321-330. 
18. Landen, D., “A Principal Plane Photo- 
alidade for Oblique Photographs,” PrOTO- 
GRAMMETRIC ENGINEERING, September 
1945, vol. XI, no. 3, pp. 245-254. 
19. FitzGerald, Gerald, “Reconnaissance Map- 
ping with Trimetrogon Photography,” 
MANUAL OF PHOTOGRAMMETRY, American 
Society of Photogrammetry, 1944, pp. 645- 
712. 
20. Van Camp, C. P. “Mahan Plotter,” 
PHOTOGRAMMETRIC ENGINEERING, vol. XI, 
no. 4, December 1945, pp. 336-339. 
21. Bean, R. K., Source and Correction of Er- 
rors Affecting Multiplex Mapping, PHo- 
TOGRAMMETRIC ENGINEERING, 1940, vol. VI, 
no. 2, pp. 63-84. 
22. Thompson, M. M., “The Twinplex, A New 
Stereoplotting Instrument,” U. .S.Geol. 
Survey Circ. 82, July 1950. 
23. Maltby, C. S., “Portable Reflecting Pro- 
jector." Surveying and Mapping, Jan.- 
March, 1952, and Samburoff, S. N., ''Auto- 
focusing Desk Projector,” PHOTOGRAM- 
METRIC ENGINEERING, Sept. 1952, vol. 
XVIII, no. 4, pp. 692-695. 
Corps OF ENGINEERS 
Photogrammetric activities of the 
United States Army Corps of Engineers 
began in 1920 when Major James W. Bag- 
ley, Corps of Engineers, was assigned to 
cooperate with the Army Air Corps in 
carrying out tests of aerial photos for use in 
topographic mapping. The first research 
was in development of suitable aerial 
mapping cameras. Major Bagley's tri- 
lens camera, invented in 1916, formed the 
basis for a series of multiple-lens cameras 
culminating in the five lens T-3A camera 
having one vertical chamber and four ob- 
lique chambers. This camera remained the 
standard precision mapping camera of the 
U. S. Army until 1940. 
A tandem T-3A camera arrangement 
was also evolved, made up of two five-lens 
T-3A cameras mounted so that their hori- 
zontal axes were at 45 degrees to each 
other. The oblique photographs when 
transformed by a special printer into the 
plane of the vertical photography, may 
be assembled with one vertical photo- 
graph to provide a near vertical 9-lens 
composite photograph. 
In 1935, the stereocomparagraph was 
invented by Captain Benjamin B. Talley, 
of the Corps of Engineers, and standard- 
ized for use of field photomapping units. 
In 1937, vertical and oblique multiplex 
projectors (normal-angle) were developed 
by the Bausch and Lomb Optical Com 
pany, under a contract with the Corps of 
Engineers, in order to provide a stereo- 
compilation instrument capable of utiliz- 
ing T-3A vertical and oblique photography 
for topographic mapping. During the same 
period experiments were begun with single 
lens wide-angle cameras. After testing 
various lenses the 6 inch metrogon lens 
with 93 degree angular coverage was adopt- 
ed in 1940 for use in the standard military 
mapping camera. 
In 1938, the Corps of Engineers issued 
a specification for wide-angle Multiplex in 
order to utilize mapping photography 
taken with wide-angle cameras; it con- 
tracted for a limited quantity. In 1939, 
these instruments were standardized for 
U. S. Army use, and in 1940 further pro- 
curement of normal-angle equipment 
ceased. 
The use of the metrogon lens neces- 
sitated the development of a distortion 
compensating reduction printer; develop-