REPORTS 
ON THE 
STATH. OT -SCIEANC EH: 
Report of the Committee, consisting of Professor G. CAREY FOSTER, 
Sir WitL1AM THomson, Professor AYRTON, Mr. J. PErRy, Professor 
W. G. Apams, Lord RayLricH, Professor JENKIN, Dr. O. J. LODGE, 
Dr. Jonn Horxtyson, Dr. A. Murrneap (Secretary), Mr. W. H. 
Preece, Mr. Hersert Taytor, Professor EvErett, Professor 
ScuusrerR, Sir W. Siemens, Dr. J. A. FLeminG, Professor G. F. 
FirzGEraLp, Mr. R. T. GuazEBrook, and Professor CHRYSTAL, 
appointed for the purpose of constructing and issuing practical 
Standards for use in Electrical Measurements. 
Tue Committee report that, in accordance with suggestions made at the 
3 last meeting of the British Association, arrangements have now been 
completed for testing resistance coils at the Cavendish Laboratory and 
issuing certificates of their value. These arrangements have been made 
by Lord Rayleigh and Mr. Glazebrook, and the report contains an account 
by the latter of the methods employed and the conditions under which 
the testing is undertaken, in order that those who use such coils may have 
a more exact estimate of the value of the test. 
The standards at the laboratory belonging to the Association, the 
values of which have been recently tested, are all single units. The best 
of these were all compared among themselves, originally by Hockin 
(‘ British Association Report,’ 1867), and again by Chrystal and Saunder 
(Report, 1876), and more recently, at various temperatures between about 
0° C. and 25°C. by Mr. Fleming in 1879-1881, and a chart has been con- 
structed, from which the resistance of any one coil at a given temperature 
between these limits can be determined. On this chart a curve is drawn 
for each coil; the ordinates of the curve represent resistances, while 
the abscissee give the temperatures. The temperatures at which the 
various resistances were originally each one B. A. Unit are known for 
the respective coils. For these temperatures the ordinates of the curves 
drawn ought to be the same, and the corresponding resistance one B. A. 
Unit. Mr. Fleming finds, however, that this is not the case. The resis- 
tances of the eight coils examined at the temperatures at which they were 
