240 SCIENTIFIC AND TECHNICAL LABOURS TO 1860. 



based on a fundamental dynamic standard, would con- 

 siderably facilitate calculations with electrical forces. 

 Although on the other hand it could be contended 

 that the great majority of calculations with electrical 

 resistances belonged to the geometrical and not to the 

 dynamical domain, and that the reproducible unit with 

 a geometrical foundation proposed by me might just 

 as well be called an absolute one as the unit of Weber 

 resting on a dynamical basis, or the modification of 

 the same which was proposed as unit on the English 

 side, yet the c. g. s. unit of resistance has been sub- 

 sequently adopted in principle as the international stan- 

 dard. I shall once again return to this in the sequel. 

 The duty, entrusted to my brother William and 

 myself by the English Government, of controlling the 

 manufacture of cables subsidized by it, caused us to 

 make very exhaustive experiments with regard to the 

 properties of submarine lines, and especially to elabo- 

 rate a rational method for the testing of their electrical 

 condition. The Malta-Alexandria cable was the very 

 first which was subjected to a systematic testing and 

 controlling during its entire preparation, and which in 

 consequence proved also perfectly faultless after being 

 laid and has remained so. Such a rational testing- 

 was rendered possible by the exact standard of re- 

 sistance above described, and by our arrangement 

 of resistance coils, which allowed the combination of 

 any desired resistances in mercury units in the same 

 manner as weights are used in scales, furthermore 

 by essential improvements, which the methods of in- 



