Pneu-mat′ic Tel′e-graph.
A telegraph used before the times of Morse and Wheatstone for communicating information by the impulse given to a column of water by pneumatic pressure. A device in which air instead of water is the transmitting medium was patented in 1868 by Count Sparre of Sweden. The transmitting apparatus consists of a drum covered by an elastic diaphragm a, to which an impulse is communicated by a disk d at the inner end of a plunger e. The air thus set in motion communicates its vibrations through the tube b to a similar elastic covering over the head of a receiving drum, over which is a disk d′ moving a rack i that gears with a pinion on the axis of the ratchet-wheel k; the movement of this wheel causes one of its teeth to lift the tail of a pivoted hammer sounding a signal on the bell h. |
| Pneumatic trough. |
