Airplanes,” C&GS Spec. Report No. 60 (un- 
published), Aug. 30, 1919. 
5. Mattison, G. C., “Aerial Survey of the Mis- 
'sissippi Delta," U. S. Government Printing 
Office, 1924. 
6. Graham, L. D., “Topographic, Hydro- 
graphic, and Aerial Survey of Lake Okee- 
chobee, Florida, C&GS Annual and Season 
Report No. 30, 1924-1925 (unpublished). 
7. Reading, O. S., Descriptive reports, topo- 
graphic (unpublished) C&GS, Nos. 4371, 
1927; 4430, 1927; 4452, 1927-28. 
8. Reading, O. S., “The Nine-lens Camera of 
the Coast and Geodetic Survey,” PHOTO- 
GRAMMETRIC ENGINEERING, Vol. 1, No. 5, 
p. 6, 1935; also Vol. 4, No. 3, p. 184, 1938. 
HISTORY OF PHOTOGRAMMETRY IN THE UNITED STATES 
9. Reading, O. S., “The Nine-lens Camera of 
the Coast and Geodetic Survey,” PHOTO- 
GRAMMETRIC ENGINEERING, Vol. 4, No. 3, 
p. 184, 1938. 
10. MANUAL OF PHOTOGRAMMETRY, American 
Society of Photogrammetry, Pittman Pub- 
lishing Co., preliminary edition, pp. 56, 
120, 1944. 
11. Tewinkel, G. C., “The Reading Plotter,” 
PHOTOGRAMMETRIC ENGINEERING, Vol. 13, 
No. 2, p. 257, 1947; also Vol. 15, No. 3, p. 
394. 
12. Swanson, L. W., “Topographic Manual,” 
part II, U. S. Government Printing Office, 
1949. 
GEOLOGICAL SURVEY 
The Geological Survey has employed 
photogrammetric methods since 1904, 
when two of its staff members, C. W. 
Wright and his brother F. E. Wright, first 
used a panoramic camera for topographic 
surveys in Alaska.! The first cameras used 
by them were improvised from commercial 
instruments by the addition of level bub- 
bles and internal scales. In 1907, C. W. 
Wright had a camera constructed specifi- 
cally for the purpose of surveying. Another 
member of the Geological Survey staff, 
J. W. Bagley, redesigned and improved 
this type of camera for use in reconnais- 
sance mapping in Alaska.? Bagley also 
designed a panoramic photoalidade to 
facilitate the use of the panoramic pictures 
in map-making. 
In 1916-17, Bagley developed a tri-lens 
camera for aerial photography, and his 
colleague, F. H. Moffitt, designed a trans- 
forming camera for tri-lens camera nega- 
tives.? In the following year, the Geological 
Survey participated with the Crops of 
Engineers and the Air Service in a program 
of photographing, with the tri-lens camera, 
several strips of country between aviation 
fields for the purpose of making aeronau- 
tical charts.? In 1918, the Survey cooper- 
ated with the Air Service in experiments 
with a gyroscopically controlled camera; 
the resulting equipment achieved control 
of the camera axis within 2 degrees. 
In the spring of 1920, the Survey used 
the tri-lens camera for a systematic aerial 
survey of parts of Santo Domingo and 
Haiti. In the same year, the Schoolcraft, 
Michigan, quadrangle was successfully 
mapped with the aid of single-lens aerial 
photographs supplied by the Army Air 
Service. The photographs were used for 
the delineation of planimetry on the field 
sheets; the contours were added by topog- 
raphers on the ground. - Following the 
success of this project, the method was 
applied to an increasing number of other 
quadrangles. 
In 1921, the Section of Photographic 
Mapping was established in the Topo- 
graphic Branch of the Survey. Besides 
the production of planimetric base maps, 
this Section soon gave part of its efforts to 
stereotopography. A semi-automatic ste- 
reoscopic plotting instrument, the Stereo- 
autograph, was received from Germany, in 
1921 and was tested by the Survey. This 
instrument employed terrestrial photo- 
graphs only, and while workable, did not 
prove to be economical. A second instru- 
ment, the Hugerschoff Aerocartograph, 
was imported from Germany in 1927; this 
was the first automatic stereoscopic plot- 
ting instrument utilizing aerial photog- 
raphy to be owned by the U. S. Govern- 
ment. Following a number of experi- 
mental projects, the Aerocartograph was 
assigned to a definite program of complete 
map construction in 1930, and several 
good maps were produced.’ 
By this time, the growing importance 
of photogrammetric methods had been 
recognized by the inclusion of a 40-page 
chapter on "Map Compilation from Aerial 
Photographs," by T. P. Pendleton, in the 
Topographic Instructions of the United 
States Geological Survey.® This was pub- 
lished in 1928. The Survey also published, 
in 1929, a report on the Alaskan Aerial 
Survey Expedition of 1926, in which it 
participated with other federal agencies.” 
When the Tennessee Valley Authority 
was established in 1933, one of the imme-