294 SEC. 10. ELECTRICITY. 



1476. Thomson's Astatic Reflecting Galvanometer, 



round glass case, for lecture purposes. Elliott Brothers. 



The most sensitive instrument yet constructed for detecting the presence of 

 a current and measuring its magnitude. 



1477. Thomson's Astatic Reflecting Galvanometer, in 



square brass case, made by Elliott Brothers. Prof. W. F. Barrett. 



The upper coil of this galvanometer has a very high resistance, the lever 

 a very low one ; the coils are used independently. 



1478. Set of Shunts, for use with galvanometers, to reduce 

 the angle of deflections of the needle 10, 100, or 1,000 times by 

 shunting off the current, so that only -fa, T ^-Q, or 10 1 00 of the 

 current passes through the galvanometer, and the remainder 

 through the shunts. Elliott Brothers. 



1479. Simple Horizontal Galvanometer, coiled with stout 

 wire of low resistance, intended especially to show thermo-electric 

 currents. Elliott Brothers. 



1480. Tangent Galvanometer, designed by Gaugain, for 

 measuring electro-motive force, resistance, &c. Elliott Brothers. 



The instrument is composed of two coils, separated by a distance equal to 

 one half their diameter ; contains three sections of stout wire, which can be 

 connected at pleasure. This instrument can be used with very powerful 

 currents. 



1481. Speaking Galvanometer, used for signalling through 

 submarine cables. The mirror and magnet are doubly suspended ; 

 glass in front and back protect the mirror and magnet from 

 draught and dust. Elliott Brothers. 



1482. Oil Vessel Galvanometer, as used in military schools, 

 for testing and signalling. Elliott Brothers, 



The coils consist of two sections of high and low resistance, which can 

 easily be brought into circuit by a switch in front of the instrument. To 

 reduce the oscillations of the needle, the instrument is provided with a glass 

 vessel for liquids, into which the vane of the needle dips. 



c. ELECTRO-DYNAMOMETERS. 



1483. Electro-dynamometer, for measuring electric cur- 

 rents which are constantly being reversed in direction. Made by 

 Dr. Meyerstein, of Grottingen. George Gore, F.R.S. 



1484. Edelmann's Absolute Dynamometer, 



M. Th. Edelmann, Munich. 



1485. Fine-wire Electro-dynamometer. 



M. Th. Edelmann, Munich. 



