Aircraft Instruments Catalog, DC Selsyn Remote Indicating, 1941

Here is an Aircraft Instruments catalog from General Electric dated August 1941.  This 34-page catalog was intended for aircraft designers and covers GE's line of DC Selsyn Remote Indicating Instruments.  Most major manufacturers of aircraft instruments introduced a line of 'remote indicating' instruments in the early 1940's, and Selsyn was GE's brand. A remote indicating instrument normally consisted of at least two components: a transmitter and an indicator. The transmitter would typically be placed 'remotely' from the panel-mounted indicator and as close to the subject of its measurement as possible. The transmitters were specific to the measurement desired: position (of flaps, landing gear, etc.), RPMs, pressure, and temperature. The transmitter communicated an electrical signal to the indicator to display the measured parameter. These were breakthrough instruments at the time, in that they permitted multiple readings (from 2, 3, or 4 transmitters) on one 3.25 inch indicator, thus