Beschreibung:

(Alexander Graham inventor of the telephone and teacher of deaf people, 1847-1922) [Notes from Bell's experiments with the Photophone], partial autograph manuscript, 12pp. of coated photographic paper, 2 with notes, 4pp. dated, 9pp. numbered, in black ink, rectos only, paper lightly oxidised to brown/grey, 4to, n.p., 26th April - 1st May 1880. *** Graham Bell's experiments with the photophone. "By early 1880, Bell had abandoned business matters relating to the telephone, and was engaged with Charles Sumner Tainter, in developing the photophone. This was an invention which enabled speech signals to be transmitted from one place to another by means of a light beam. The invention utilized a selenium cell, in which the photoconductive property of selenium (discovered in 1873) was used. Bell in 1898 was of the opinion that the photophone was his greatest invention, and in 1921 he stated his view that ‘in the implementation of the principles involved’ the invention was ‘greater than [that of] the telephone’. However, the rapid development of radio and the very limited range of the photophone were not conducive to its general application." - Oxford DNB.