36 Prof. H. F. Weber on Electromagnetic and 



There were found : — 



April 4,1876, 



1 S. M. IT. 



= 0-9551 xHW mil!im 

 V sec. 



5 



,, , ,, 





= 0*9532 xlO 10 „ 



,, , ,, 





= 0-9570 xlO 10 „ 



7 





= 0-9565 xlO 10 „ 



,, ", ,, 





= 0-9548 xlO 10 



„ 10, „ 





= 0-9555 xlO 10 „ 



The mean value of these six series is 



1 S.M.U. =0*95535 xlO 10 . 



In the second group of trials the spirals were pushed so far 

 asunder that the distance between their central planes ivas as 

 closely as possible equal to the mean radius of their windings. 

 For this position of the spirals (2D = 164*4 millims. nearly) 

 the difference of the logarithmic decrements amounted to only 

 about 0*0172 ; at the same time the expression of G was ap- 

 proximately independent of the pole-distance of the magnet : 



for the case that D = — , 



G= 



5X/5.EL 1 15 R 2 + lp*\lbp? IV, 



and the value of the last member within the square brackets 

 amounts to only — 0*00028. 



The results found with this arrangement of the experiments 

 were : — 



pril 12, 



1876, 



„ 13, 



„ 



„ 14, 



„ 



„ 15, 



,, 



,, 16, 



,, 



» 17, 



„ 



1 S. M. U. =0*9531 x 10 10 ( E?y™A 



\ sec. / 



= 0*9543 xlO 10 

 = 0*9542 xlO 10 

 = 0*9534 xlO 10 

 = 0*9555 xlO 10 

 = 0*9528 xlO 10 



The mean value amounts to 



S.M.U. =0*95388 x 10 10 (^^E;). 



\ sec. / 



/millim. 



During the summer of 1876 the multiplier was taken to 

 pieces ; in the autumn I once more subjected all the dimen- 

 sions of both spirals to a cathetometric examination, and again 

 put the spirals together so as to form a multiplier of the sort 

 last described. The moment of the magnet had, in conse- 

 quence of continual use at different times, become so consi- 

 derably diminished that the difference of the logarithmic de- 

 crements > 2 — \ x now amounted to only about 0*0161. 



