4T8 THE ADDRESSES, LECTURES ETC., OF 



in commerce is rendered impossible by the fact that the Standards 

 Office refuse to affix their stamp to any particular rod divided 

 metrically. The legality of metrical measurement is further sub- 

 stantiated by the important fact that England was officially 

 represented at the Paris Electrical Congress, which has adopted 

 for all electrical and I may therefore almost say for all accurate 

 measurements of the future, the C.Gr.S. (the centimetre-gramme- 

 second) system, proposed, not by our neighbours on the continent, 

 but by a committee of the British Association, comprising leading 

 men of physical science, and as the result of many years of 

 arduous labour. 



The electrical conductivity of a wire varies, as is well-known, in 

 the exact proportion of its sectional area, and in all questions of 

 electric quantity and measurement, the diameter of the wire is, as 

 it were, the starting point. Great indeed will be the complication 

 that must arise if a wire gauge is practically enforced which has 

 absolutely nothing in common with the fundamental measures 

 employed in all scientific work, and that are of universal applica- 

 tion as regards electrical measurement. Nor can it be said that 

 the proposed wire gauge is based upon a system possessing rival 

 merits, its leading feature being that it expressly disregards all 

 system whatsoever. In examining, for instance, the current 

 numbers of the new wire gauge from 1 to 12, we find that the 

 successive increases of diameter from number to number are repre- 

 sented by the decimals '024, -024, '020, '020, '020, '016, '016, 

 016, -016, -012, -012 of an inch, or '06095952, '06095952, 

 0507996, -0507996, '0507996, '04063968, '04063968, '04063968, 

 04063968, '03047976, '03047976 of a centimetre ; it is thus clear 

 that the authors of the gauge did not aim at making the numbers 

 advance according to a uniform increment of progression of 

 diameter. But it will be said that they may have been guided 

 by a desire to establish a uniform progression according to the 

 sectional areas of the wires ; but in calculating those areas I find 

 that the increments of increase are '010858, '009952, -007603, 

 006974, -006346, '004624, '004223, '003820, -003418, '002300, 

 002073 of a square inch, or expressed in square centimetres, 

 07005038, -06420538, -04905075, '04499276,'04094121,'02983173, 

 02724468, '02464473, '02205122, '01483845, '01337395, show- 

 ing that neither had the projectors of the new gauge any intention 



