42 



REPORT — 1903. 



interesting to note that the temperature coefficients of some of the coils 

 are appreciably different from the old values of 1892. 



Table X. — Sho%uing the old and new values of the Temperature Coefficients 



of various Coils. 



Co^nparison of the Unit of Hesistance employed at the Reichsanstalt 

 and that of the N.P.L. 



By the N.P.L. unit is meant the unit of resistance as obtained from 

 the old B.A. coils.' Assuming that all the changes have been successfully 

 interpreted, the unit at present employed in the Laboratory should be the 

 same as that employed in the Cavendish Laboratory in 1898 and at 

 Edinburgh in ] 892. 



A comparison of the two units was rendered possible in the spring. 

 Two Wolff coils, Nos. 780 and 738, of nominal values 1 ohm and 10 ohms 

 respectively, were despatched to Germany last winter. Their values were 

 determined in Reichsanstalt units (termed international ohms) in March, 

 and the coils immediately returned to the Laboratory. Unfortunately 

 both coils fell in value two or three parts in the hundred-thousandth figure 

 during their journeyings. The values given in the table are those deter- 

 mined on their return. 



In addition, five new coils were received varying in value from -i^i\v 

 to 10,000 ohms. These enabled a more complete comparison to be made. 

 The Laboratory value was deduced by building up from the unit, and also 

 by direct comparison with coils of similar value. 



Table XI. — Results of Measurements of various coils at the Reichsanstalt 

 aitd at the Laboratory, March 1903. 



1 X N-P.L, unit =1 -01 358 B,A,U 



