Public service of Photo-telegraphy in Japan

Describes a system of picture telegraphy in which the transmission is effected by light reflected from the picture. The pitch of the scanning spiral is 6 lines per mm., and the time required for a full-size picture of 18times26 cm. is about 6 min. with the high-speed set, and 20 min. with the slow-speed set in use. Synchronism is secured by using synchronous motors at both ends and superposing a synchronising current on the picture currents, sorting these out by suitable filtering arrangements.