(1) A synchronous telegraph with direct—that is, uncoded—registration of the transmitted letters and numerals at the receiver. It was invented by B. S. Iakobi in 1845.
(2) The first letter-printing telegraph. It was invented by B. S. Iakobi in 1850. The principle of synchronous operation of the transmitter and receiver, which was used for the first time in the Iakobi telegraph, became the basis for the operation of all later telegraphs.