Ernst Ruhmer - Téléphonie sans fil - 1909

Ernst Walter Ruhmer (1878–1913). Wireless Telephony. Paris, Librairie générale scientifique et industrielle H. Desforges, 1909, ix-225 pp.

One quarto volume (260 x 170 mm), half-cloth with corners, bradel binding, black leather title-piece (period binding). Good condition of the binding. Interior fresh, with no foxing. Covers preserved.

First French translation adorned with 151 figures in the text

Ernst Walter Ruhmer, a German physicist, was a pioneer of wireless telephony through optical transmission. In 1909, he significantly improved Alexander Graham Bell’s photophone by using more sensitive selenium cells, enabling vocal communications through a light beam over longer distances. His work, though less well known than radio, opened the way to modern optical communication applications and demonstrated the potential of wireless technologies before the era of dominant radio waves.