5//e WILLIAM SIEMENS, F.R.S. 

 ami because JFj-tU) IF, 



4 l -81I10 1 = . 



I 



10 ' 000+ 



nn 



loo 



00 W, being with our instruments equal to 70 units, we obtain 

 by introducing instead of 10,000 units 9,930, 



E 1 



sin d>, = 



loo 10,000 



Kliminating E from the first formula, and combining it with 

 the second one, we obtain 



sin 

 in which formula x is given in millions of units. 



No. 2. Specific Resistance of Insulating Materials. 



Derivation of the formula for calculating the specific insulation 

 resistance. Mr. Werner Siemens obtained the same formula which 

 Professor William Thomson arrived at in a very elegant manner 

 in a more simple way. 



If d jc represents the thickness of a differential cylinder at the 

 distance x along the length axis of the cable, its resistance will be 



d x 



2 IT X / x 



and the whole resistance equal to 



R 



-=_]_, TV logy- 



2irl\ J x 2ff j x 



No. 4. Charge and Distribution along t/te Wire. 

 Let A B (Plate 1, Fig. 4) represent a given length I of uncoiled 



