Measures for Progress: A History of the National Bureau of Standards

190 THE WAR YEARS (1917-19)
ing standard wavelengths of light, particularly in the spectra of neon, helium,
and iron, by photographic means. Making these observations required
a broad knowledge of the underlying complex elements of photography.
It also drew attention to the fact that highly sensitive plates capable of photo-
graphing the wavelengths of red and infrared light could not be purchased
commercially. Preparing their own plates, Bureau spectroscopists under
Dr. Meggers made a systematic study of the spectra of some 50 of the
chemical elements, and in 1917 began photographing stellar and solar spectra
to determine their composition.
With the war, the spectroscopy section turned to military problems of
aerial photography. By then physicists both here and abroad were using
plates at least four times as sensitive and fast as the best commercial
orthochrornatic (sensitive to blue, green, and yellow) and panchromatic
(sensitive to all colors) plates in use by the military. The Bureau phyicists
were also using new dyes of British manufacture, devised to replace German
aniline dyes, and following a series of experiments offered their adaptation
of these dyes to the Air Service, for use in photographing battle terrain
through haze and smoke and detecting military works under camouflage.
Extensive experiments with the red-sensitive plates were carried out at
Langley Field in the spring and summer of 1918, but 'because of the fixed
idea of the military that the Bureau plates were still in an experimental
stage, they were never used overseas. Before the war ended, however,
their practical use had been completely demonstrated, and with the design
and construction of new photographic lenses for use with red light, the
importance of red-sensitive plates in military photography was fully
acknowledged.74
Bureau scientists also designed a new airplane camera using film
instead of plates, and at the time of the armistice had under construction for
Ordnance a special camera that photographed the inside of machine-gun bar-
rels to determine their degree of deterioration—a piece of technology enor-
mously important in gunmaking and maintenance.75 Sharing its laboratory
space, the Bureau provided facilities to the Engineers, the Geological Survey,
and the Navy for camera and lens designing and testing and for camera mech-
anism testing by the Signal Corps. Among the guest scientists in the optical
laboratories was Albert A. Michelson, Stratton's former superior at Chicago,
who came on his first visit to the Bureau to work on new long-range binoculars
he had devised for the Navy, and later returned to test the optics of the short-
"War Work," pp. 202—207; NBS Annual Report 1918, pp. 83—84; Annual Report
1919, pp. 115—118; letter, SWS to Capt. Edward J. Steichen, Air Service, SOS, France,
Dec. 3, 1918 (NBS Box 14, IPO).
"War Work," pp. 186—187; NBS Annual Report 1919, pp. 141—142.