38 



REPORTS ON THE STATR OP SCIENCE. 



Table II. 

 Giving the Values of the Coils in 1879-81, //-(mw Flemings Chart. 



If we tentatively adopt as the B.A. unit at any date the exact mean 

 of the resistances of the coils A, B, C, D, E, G at the temperatures at 

 which they were originally said to be equal, the values of the coils at 

 16°-0 C. in 1867, 1876, 1879-81, 1888, and 1908 are as given in 

 Table III. This table has been very easy to compile, because only the 

 differences between the resistances of the coils at the various dates, and 

 their temperature coefficients, were required. 



In all the tables of this Appendix the values of high-temperature 

 coefficient coils are given within 1 part in 100,000 ; but as the errors of 

 observation must often have exceeded the change in resistance corre- 

 sponding with a change in temperature of a coil of 0°-05 to 0°-l C, too 

 much significance must not be attached to an apparent change in resist- 

 ance, corresponding with a difference in temperature of a coil of a tenth of 

 a degree. 



It is clear that changes of very considerable magnitude have taken 



Table III. 



In this table it is assumed that the B.A. unit is equal to the mean of the coils 

 A, B, C, -D, E, G at the temperatures at which they were found by Hockin 

 in 1867 to be correct, and that this mean has not altered. 



Values at 16°-0 C. 



For a note as to this value see p. 39. 



