History of the Typewriter

—313— purposes. The types are arranged on a type-wheel or quadrant, as in the earlier models of the Hammond, and mov0 up and down on the post according to the depression of the shift-keys. On the depression of a key, the further end of the lever tilts up, and forces up a check-pin, which not only arrests the movement of the wheel, but also sets in motion the synchronizing arm, and the first impulse is sent to line. ‘‘ This arm, which is the most vital part of the apparatus, and travels in a vertical plane, is operated from the axis of the circle, corresponding to the quadrant and travels round the circular path until its progress is arrested by impact with the projecting check-pin of the depressed type key. The corresponding letter is then printed, and the synchronizing arm is then returned to its original or zero position by means of an electro-magnet ” From this it will be seen that what in the Hammond is termed the driver-arm (that is, the arm which directs the movement of the type-wheel), serves not only its original purpose m the Zerograph, but also sets the synchronizing movement in motion, in manner not unlike in theory, but differently in practice, to the synchronizing gear previously It would be impossible, without a very lengthened explanation and the use of much highly technical language, to explain the method by which the various movements are made, but a fully detailed account may be seen in 1 ne Scientific American for October 17th, 1903. This machine takes its name from the fact that after the depression of any type-key, the synchronizing arm must return to the normal point of rest, or zero, before another type can be printed, and for this reason misprints are rendered almost impossible. A speed of thirty words per minute can be attained by an operator after very little practice. To apply the Zerograph to wireless telegraphy, it is only necessary to connect it to the usual apparatus utilized for that work, the typewriter being substituted for the Morse transmitter. To ensure satisfactory and successful operation, however, the inventor has also devised several special contrivances, such as an automatic coherer to enable rapidity in transmission and receiving to be attained and other items. The Zerograph is stated to be most favourably adapted to ether communication, owing to only two impulses being necessary to transmit or receive any sign.