ON STANDARDS OF ELECTRICAL RESISTANCE. 



351 



In constructing the standard coil, in consideration of the much greater 

 range of velocities used in 1864, the 1864 mean value vras allowed to have 

 five times the weight of the mean value ohtained in 1863. 



Appendix B. — On the Electrical Permanency of Metals and Alloys. 

 By A. Matthxessen, F.ILS. 

 In Appendix A. of the Report of your Committee of last year, I gave the 

 results of some experiments made to test the electrical permanency of some 

 metals and alloys. On August 5 of this year I re-tested them, and give the 

 results in the following Tahle, taking the conductiug-power of No. 15 = 100-00, 

 as was done in last year's Report. 



From the ahove it will be seen that the following -wires have not sensibly 

 altered in their conducting-power during the space of two years. 



* Without taking into consideration the corrections due to temperature, I placed in 

 last year's Report these two wires with those whose conducting-powers had changed. 



