Early 20th Century military amplifiers. Historical image of large amplifiers being used to listen for approaching enemy aircraft. Photographed at the US Air Force base in Bolling Field,Washington DC,USA. Published in 1921 | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Library of Congress |
Bildgröße: | 4724 px × 3798 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |