Influence of Temperature on Electric Conducting Power. 405 



ducing the motion, and accordingly that the period of the changes 

 would be shorter than in a circuit of greater resistance, although the 

 mean currents in the two circuits, as measured by a galvanometer or 

 voltameter, might be the same.] 



" On the Diurnal Tides of Port Leopold, North Somerset." By 

 the Rev. Samuel Haughton, M.A., F.R.S. 



"On the Posterior Lobes of the Cerebrum of the Quadrumana ." 

 By "William Henry Flower, Esq., F.R.C.S. 



" On the General Forms of the Symmetrical Properties of Plane 

 Triangles." By Thomas Dobson, Esq., B.A. 



' ' Note on Ethylene-Dichloride of Platinum." By P. Griess, Esq., 

 and C. A. Martins, Ph.D. 



January 16, 1862. — Dr. William Allen Miller, Treasurer and Vice- 

 President, in the Chair 



The following communications were read : — 



" On the Development of Striped Muscular Fibre in Man, Mam- 

 malia, and Birds." By J. Lockhart Clarke, Esq., F.R.S. 



" On the Influence of Temperature on the Electric Conducting 

 Power of the Metals." By A. Matthiessen, Esq., F.R.S., and M. 

 von Bose. 



In the first part of the paper we have described the apparatus used 

 for the experiments, together with the precautions taken to ensure 

 correct results ; in the second we have given the results obtained with 

 the pure metals — silver, copper, gold, zinc, tin, arsenic, antimony, 

 bismuth, mercury — and the metalloid tellurium. The conducting 

 power of the wires, or bars of each, was determined at about 12°, 25°, 

 40°, 55°, 70°, 85°, and 100° C. ; and from the mean of the eight ob- 

 servations made with each wire (four at each temperature on heating, 

 and four on cooling), we deduced a formula by the method of least 

 squares for the correction of the conducting power for temperature. 

 It was found that the conducting power or resistance of a metal does 

 not decrease or increase in direct ratio to the temperature, as stated 

 by Becquerel*, Arndstenf, and Siemens £, who assume that the 

 formula for the correction of resistance for temperature between 

 0°-100° may be expressed by 



but that, on the contrary, the formula must be 



\=X + yt + yt 2 , 



where X is the resistance at t degrees, x the resistance at 0°, and y 

 and y constants. One fact seems to have escaped the observation 

 of former experimenters, namely, that when a wire of a metal is 



* Ann. de China, et de Phys. (3) xvii. 242. f Pogg. Ann. civ. 1. 



% Pogg. Ann. cxiii. 91. 



