[Major William F. Friedman, chief of the signal intelligence, explaining the principles of intricate ciphering machine to Louise Newkirk, at the War Department, Washington, D.C.], 1930 Aug. 16.

CREATOR:
Underwood & Underwood

Fort Riley, Kansas. Decoding a message
at the message center which was established by the Signal Corps during a field problem, April 1942.

CREATOR:
Jack Delano, photographer