496 SCIENTIFIC RECORD FOR 1882. 



adoption by tlie International Congress of Electricians, held in Septem- 

 ber, 1881, of the volt, ohm, conlomb, ampere, and farad. To these, 

 however, he suggested that some others should be added. For the unit 

 of nmgnetic quantity he adopted Clausins's suggestion, and proposed 

 the name "weber." For the unit of electrical power or rate of work, 

 i. e., the power conveyed by the current of an ampere through the dif- 

 ference of potential of one volt, he proposed the name " watt." For the 

 unit of intensity of magnetic field he suggested the name i)roposed by 

 Thomson, of "gauss," the gauss being the intensity of field produced 

 by a weber at the distance of one centimeter, and a weber the absolute 

 c. G. s. unit strength of magnetic pole. Two ])oles, each of one weber 

 strength, at one centimeter distance, will attract with the force of one 

 dyne. For the unit of heat, produced in one second by one ampere of 

 current flowing through one ohm resistance, he proposed the name 

 "joule." Its value in absolute measure is IC^ c. G. s. units, and there- 

 fore, taking Joule's equivalent as 4.2 x 10" units, it is the heat neces- 

 sary to raise 0.2.38 gram of water one degree centigrade. {Nature^ Au- 

 gust, XXVI, p. 390.) 



The Congress of Electricians delegated to an International Conference 

 (1) the final determination of the ohm, (2) the investigation of earth cur- 

 rents and atmospheric electricity, and (3) the standard of light. This 

 conference met in Paris, in October, 1882. As regards the ohm, i. e., 

 the length of a mercury column one square millimeter in section, whose 

 resistance is equal to 10^ c. G. s. units, several values were before the 

 conference. These are, Kohlrausch's, 1.0593 meters; Eayleigh's (by 

 B. A. method), 1.0024; (by the method of Lorenz) 1.0620; Glazebrook's, 

 1.0G24; H.Weber's, l.OGll; W.Weber and Zollner's, 1.0552; Eowland's, 

 1.0572 ; Dohrn's, 1.054G. But opposed to these is F. Weber's value, 

 1.0471, which is very near the B. A. ohm. So that the conference 

 postponed further action, and recommended' experimentalists (1) to 

 compare their resistances with the standard of resistance which the 

 French Government will furnish; (2) to compare the induction coils 

 by Kohlrausch's method with the wire circuit; and (3) to use in their 

 measurements the modified and improved method of Lorenz. The 

 second section resolved that the various Governments be requested 

 to favor regular and systematic observations of atmospheric electric- 

 ity upon their systems of telegraph; that the study of storms should 

 be undertaken in every country ; that wires independent of the tele- 

 graph system should be provided for the special study of earth currents; 

 and that, as far as practicable, the great subterranean telegraph lines, 

 especially those running from south to north and from east to west, 

 should be utilized for the same j)urpose, the observations in the ditter- 

 ent countries taking place on the same day. The third section ex- 

 pressed the opinion that the light emitted by a square centimeter of 

 melting platinum would furnish an absolute standard. The conference 



