Section 44.—INDICATING SPEEDS, &c.
[784] & [785]. Hand (portable) indicator, to indicate speed of revolution of a shaft, &c., by simple wheel work and dial plate.
[786]. Governor gauge, indicates the speed by the angle of the balls moving a finger on a vertical scale.
[787]. Steam engine indicator, of which there are many varieties. Macnaught’s, Richards’, Darke’s, Kraft’s, Casartelli’s, &c., are examples, in which a small steam piston operates a marking point by the varying pressure of steam acting against a spring; the paper is usually coiled on a cylinder having a reciprocating motion by a string from the engine.
[788]. Morin’s dynamometer. Consists of two belt pulleys connected by a spring; one receives the strain of driving belt, and the other transmits it, the spring indicating the tension on the belts.
[789]. Regnier’s dynamometer indicates the tension on the connections by contraction of the spring operating a dial plate.
[790]. Bourdon tube pressure indicator. The tube is of flat section, and its curved portion expands with the pressure, operating a finger on the dial by rackwork.
[791]. Worm gear and dial to register the number of revolutions. See [No. 1559].
Other forms of pressure gauges are—1st. The mercurial gauge, in which the pressure is indicated by the height of a column of mercury in a glass tube. 2nd. The water gauge, in which a column of water replaces the mercury. 3rd. The spring balance (see [No. 1729]). See also [Nos. 1730], [1728].