293 SEC. 10. - ELECTRICITY. 



Reflecting Astatic Galvanometer, with coils of low 

 resistance, and with telescope and scale, for measuring thermo- 

 electric currents of very low intensity. Focal distance of telescope 

 and scale about three metres. Made by Ruhmkorff, of.Paris. 



George Gore, F.R.S. 



1442. Galvanometer, by Colladon, with coils insulated by 

 a special method. This instrument was used by the inventor for 

 measuring the intensity of currents produced by electric friction 

 machines, and by the clouds, in 1826, and by electric fish, in 

 1831. Professor Daniel Colladon, Geneva. 



The inventor used this same galvanometer in 1831, for studying the distri- 

 bution of the electric poles upon torpedoes, and the strength of currents pro- 

 duced by animal electricity. 



Annales de Chimie et de Physique, 1826, vol. S3. 



Peclet, Traite de Physique, 1832, vol. 2, p. 221 to 225. 



Menioires de 1' Academic Royal e des Sciences, Institut de France, vol. 10, 

 p. 74. 



1443. Balance Galvanometer, giving indication of current 

 in grains or other weights in scale pans, which may be adjusted to 

 any standard. Invented by contributor in 1848. 



William Sykes Ward. 



1444. Galvanometer, designed by Colladon for Currents of 

 Electrical Statics. 



Geneva Association for Constructing Scientific Instru- 

 ments. 



Apparatus for demonstrating that the electricity drawn from friction 

 machines, from the clouds, &c., produces currents, of which the direction and 

 the intensity are measured by the deviation of the magnetic needle of a 

 galvanometer. 



1445. Marine Galvanometers used on board H.M.S. " Aga- 

 memnon" and the U.S. Frigate " Niagara," in the Atlantic Cable 

 Expeditions of 1858. Sir William Thomson. 



A light mirror, weighing 30 milligrammes and 9 millimetres in diameter, 

 with single needle cemented to its back, suspended by stretched platinum 

 wire in centre of field of coil composed of two bobbins of fine copper wire. 

 Micrometer screws to adjust zero by torsion of upper and lower parts of 

 platinum wire. The first words transmitted across the Atlantic were from the 

 " Agamemnon " approaching the Irish coast, and were read op one of these 

 instruments on board the " Niagara " approaching Newfoundland. (Encj r clo- 

 psedia Britannica, Art. Telegraphs (Electric), VII. 6, and VIII. 4.) Made by 

 White and Barr (now James White), Glasgow. 



1446. First Instrument for recording Signals through 

 Long Submarine Cables, by curve of perforations produced by 

 sparks from a Ruhmkorff coil guided by a platinum wire moved 

 by a needle under the influence of the varying current from the 

 cable. Sir William Thomson. 



