Page 30 of 61
Acoustic Mirrors at Denge, a site of the British Royal Air Force near the Channel, where some experimental models were built in the 1920s and 1930s. One is…
Dutch personal horns. Rotating acoustic listening device developed for the Dutch army as part of air defense systems research between World Wars I and II, 1930s.
German acoustic/optical locator, 1917. A junior officer and an NCO from an unidentified Feldartillerie regiment wearing combined acoustic/optical locating apparatus.
Japanese ‘War Tuba’ in an air field, 1921. After WWI aircraft detection became increasingly important to warfare. Before radars acoustic amplifiers and mirrors with different designs were used…
Acoustic listening device developed for the Dutch army as part of air defense systems research between World Wars I and II.
Helen Soros works the new pneumatic tube system to take cash at Marshall Fields store in Chicago, November 26, 1947.
N.Y. Post Office Pneumatic Tube, c. 1912. The first pneumatic tube mail system was installed in New York City in 1897. Each tube could carry between 400 and 600…