GB191503544A - Improvements in Indicating Devices for Telemeters having the Base-line within the Instrument. - Google Patents

Abstract

3544. Zeiss, C., [Firm of]. March 31, 1914, [Convention date]. Range - finders. - In apparatus of the selfcontained base type, the measuring element or prism, in order to indicate the range, is connected with a variable electric resistance in such a way that the magnitude of the resistance alters in proportion to the movement of the measuring-element. In one form, the variable resistance is included in a circuit of constant voltage, so that the range may be indicated directly by the reading of an ammeter, a resistance box being placed in the circuit for adjustment purposes. In the modified arrangement shown in Fig. 2, the frame of the measuring- element a is provided with a conducting-roller b running on a resistance wire c, and with a conducting-rod b<2> sliding in a guide d. The part of the resistance wire c between the binding-screw c' and the roller b forms one arm of a wheatstone bridge supplied with current from a battery r, the adjacent arms containing resistances h, i respectively. The fourth arm is formed by the part of a resistance wire k between a binding-screw k<2> and a roller l on a sliding rod l<1>, this effective part being caused to vary in inverse proportion to the resistance c by means of an electromotor p, which is capable of revolving in either direction and is controlled by a galvanometer relay o in the zero line of the bridge. The roller l carries a pointer l<2> moving over a range-indicating scale n.