354 



ABSTRACTS OF SCIENTIFIC PAPERS 



PART V. ELECTRICAL MEASUREMENTS DERIVED FROM THE FIVE 

 ELEMENTARY MEASUREMENTS. 



Electric potential. 



Density resultant electric force 



electric pressure. 

 Tension. 

 Conducting power, specific resistance, 



and specific conducting power. 

 Specific inductive capacity. 

 Heat produced in a conductor by a 



current. 

 Electrochemical equivalent. 



Electromotive force of chemical affi- 

 nity. 



Tables of dimensions and other con- 

 stants. 



No'e to the table of dimensions, by 

 Professor Clerk Maxwell. (Omitted 

 in reprint.) 



Magnitude of units and nomencla- 

 ture. 



XI. Appendix D to the Second Report of the Committee on Electrical 

 Standards. ' Description of an Experimental Measurement of 

 Electrical Resistance, made at King's College.' By Professor 

 J. Clerk Maxwell and Messrs. Balfour Stewart and Fleeming 

 Jenkin. Part II. 'Description of the Apparatus] by Mr. Jenkin. 

 'British Association Report for 1863,' p. 163 ; Reprint, p. 96. 



This paper describes and illustrates the apparatus constructed by 

 the Committee to carry out Sir W. Thomson's method of finding in 

 absolute measure the resistance of a coil of known dimensions by 

 spinning it with known velocity about a vertical axis and observing 

 how a magnet suspended at the centre of the coil is deflected by the 

 currents which the earth's horizontal magnetic field induces in the 

 revolving wire. The B. A. unit of resistance was determined by means 

 of this apparatus. The paper includes a notice of a modified Wheat- 

 stone Bridge in which a group of coils arranged in multiple arc 

 form a means of adjusting the resistance in one arm of the bridge. 

 It is added that the idea of using large coils combined with small ones 

 in multiple arc to obtain extremely minute differences of resistance 

 had been suggested to the writer by Sir W. Thomson. 



XII. Appendix A to the Third Report of the Committee on Electrical 

 Standards. ' Description of a further Experimental Measure- 

 ment of Electrical Resistance, made at King's College.' By 

 Professor J. C. Maxwell and Mr. Fleeming Jenkin, with the 

 assistance of Mr. Charles Hockin. ' British Association Report 

 for 1864 ; ' Reprint, p. 115. 



This paper gives the results of a second group of experiments by 

 which the B.A. unit of resistance was again determined by the same 

 method as had been used the year before. The Committee made 

 this and the former set of determinations (Art. XI.) the basis of 



