36 HISTORY OF PHOTOGRAMMETRY IN THE UNITED STATES 
brothers, in one of the earliest military 
air mapping operations of our Army. Later 
the Brock camera was further developed, 
so that its magazine held 48 optically flat 
glass plates, each 6 inch by 8 inch in a 
single magazine. 
In 1922 the first topographic map made 
in the United States by aerial photo- 
grammetric methods was compiled by 
Brock with the new equipment designed 
and built by his company. This equipment, 
which was independent of any European 
development or designs, was unique in its 
breakdown of the mapping process into 
separate operations for each phase of the 
work. It made use of several instruments, 
rather than one or two complex instru- 
ments. The whole process was an inte- 
grated ''production line" for precise map- 
ping.* 
In the early Twenties Frank E. Wey- 
mouth, a hydraulic engineer of wide ex- 
perience, joined Norman Brock. The 
Brock & Weymouth organization made its 
first commercial survey in 1923: a water 
power study of the Saluda River in South 
Carolina. Utility officials estimated it 
saved $750,000 in dam site locations. 
Later the company completed topographic 
mapping contracts in Canada, France, and 
Italy, as well as contracts and demonstra- 
tion work in the United States. 
In 1927, the Chief Topographic En- 
gineer of the U. S. Geological Survey, 
Colonel C. H. Birdseye, wrote Norman 
Brock: “I want to record my appreciation 
of the demonstration of your special 
process of topographic mapping, in which 
you use aerial photographs taken on flat 
glass plates and other special instruments. 
It has been interesting to bring together 
the two maps independently made (of the 
Bushkill quadrangle), one by our ground 
method and the other by your aerial 
method. In a broad way there is general 
agreement between the two. After our 
office comparison of the maps I spent 
parts of two days on the ground examining 
certain points of difference. These com- 
parisons are strikingly favorable to your 
map. Most of this is due to the correctness 
of the photographic detail, but some of it 
* For pictures and a diagram, ‘Operations 
of the Brock Process,” see paper by Robert Sin- 
gleton in PHOTOGRAMMETRIC ENGINEERING, 
Vol. XIV, pp. 538-544.—Ep. 
is due to the fact that our map is below our 
standard product. ... You have demon- 
strated most convincingly the accuracy of 
the Brock process.” 
After spending great sums of money and 
much time in the development of the 
equipment and method, the Brocks had 
much difficulty in putting this revolution- 
ary, new process across with public or 
commercial engineering organizations in 
need of mapping services. It was hard to 
tell an old planetable surveyor that maps 
equal to his best work could be produced 
by the use of air photos and a limited 
amount of ground control. At this time, 
during the early days of aviation, anything 
connected with flying and its sketchy and 
unreliable aircraft was treated with great 
skepticism. Thus, the Brocks suffered 
from being many years ahead of their time 
with precise procedures which have since 
become standard. The general acceptance 
of the process was very slow, and after 
completion of the Boulder Dam mapping, 
Brock & Weymouth went out of business 
in early 1930. 
The equipment was acquired by Aero 
Service Corporation in 1938, and the great 
hopes of its inventors have been fulfilled 
in the wide use and acceptance of the 
equipment since that time. In the early 
Forties the Brock Process was kept very 
busy in mapping for war plants, starting 
with a 2 foot contour map at Weldon 
Springs, Missouri, and including more 
than a dozen such plants, among them the 
Oak Ridge A-bomb installation in Tennes- 
see and the Sunflower Ordnance Plant in 
Kansas. Postwar work included the vast 
Missouri Valley mapping work (4,800 
square miles of contour mapping), and 
over 1,000 miles of highway location 
mapping with the Brock equipment. 
But Aero Service Corporation, founded 
in 1919, was a pioneer in other directions. 
Oldest flying corporation in the world, it 
executed the first modern highway survey 
in the United States in 1924. In 1932, all 
of the State of New Jersey was photo- 
graphed as a single project, and marked 
the first complete State to be so mapped. 
The first aerial cameras to expose 9 inch 
by 9 inch film and the first precision film 
cameras were developed and made in 
AERO’S shops. 
Later, in 1938, the Company developed 
a 9 inch by 9 inch camera with 4 inch and