74 ON MAGNETISM. 



r* 



as great as before, and -^ will be (numerically) p~* times 



jL 



as great as before. The experiment of Article 32 gives 



t 2 



'JE4 = -fj^- M; T is not altered by the new units ; but M y 



which depends on product of mass by square of distance 

 from center of angular motion, will be 



TfJ 



times as great as before. The product of -r by EA will 



A. 



therefore be (numerically) - times as great as before : 



and the numerical expression will be A/ times as 



great as before. '* . 



The value of p is 3047941: that of q is 647989$^; 

 therefore the new numerical expression for E on the 

 Metric system will be formed by multiplying that on 



the English system by or 0-46108,4 ^ 



The same numerical result would have been obtain- 

 ed if the units employed, in the Metric system, had 

 been the metre and gramme. 



34.. Special values of E : historical physical change 

 in the value : lines on the Earths surface passing through 

 points of equal horizontal force. 



The mean value of E found at Greenwich in the 

 year 1867 was 3*851 in English measure, or 1776 in 

 Metric measure. In 1848 its value at Greenwich, in 

 English measure, was 3722. The increase in 19 years 



