A Pianola is operated by suction, through the exhaustion of air from a bellows normally distended by springs as shown in 5 in the accompanying illustration. The exhauster is operated by the pedal 1; the board 3, with its small bellows, exhausts the air from 5 in the chest 7 by a series of valves not shown in detail. When the air is pumped from 5 by the motion of exhauster 3, this bellows collapses notwithstanding the retractile spring 6. The exhaust condition may now operate upon any chamber of the whole mechanism through trunk 7 and pipe 8. When a perforation in a music sheet 16 passes over its corresponding duct in tracker 15, air is admitted through tube 14, which relieves the diaphragm in chamber 9, made of a very thin piece of leather, upon which rests the stem of valve 11. Owing to the suction in chamber 9 this diaphragm instantly raises and shuts the outer port 23 by means of valve 11, giving a free communication from pipe 8 through chambers 9 and 12, to the striking pneumatic 13 which collapses, and through pitman 19 and finger 20 strikes the key. As soon as the unperforated part of the music sheet has passed over the hole 15 in the trackerboard, the flow of air through pipe 14 is cut off and the pressure on the small diaphragm in chamber 9 has ceased to be operative, and valve 11 immediately drops and allows air to pass into striking pneumatic 13, through port 23, so that pneumatic 13 and the key levers come back to their normal positions. [Illustration: Mechanism of Pianola.] [Illustration: A Before calling. B Calling the fifties. C Calling 58 from among the fifties. Automatic telephone. Automatic Electric Co., Chicago.] [Illustration: CALLING 6 ON THE AUTOMATIC TELEPHONE AUTOMATIC ELECTRIC CO., CHICAGO.] Automatic Telephones.