the Electro-magnetic Po-xer by Sch-joeigger's MiiltipUer. 44.9 



between which the needle oscillated, and took the mean of 

 them. 



7. If we now calculate the mtensities of the magnetic power 

 of the connecting wire, we find, that if the power of one single 

 convolution is made =1, the power of n windings is =72, 

 and that this apparatus may be more appropriately called a 

 multiplier than a condensator. The values found are as 

 follows : 



That the law just now established does not exactly apply 

 for 26 convolutions, cannot in any respect be considered as an 

 instance of inaccuracy in it, but is probably an error in the 

 observation of a convolution. 



The law is confirmed moreover in the following manner : 

 If the connecting wire intersect the magnetic meridian under 

 an angle of 90°, then we know that the needle is tui-ned back, 

 if the electric stream passes from W. to E. After I had pre- 

 viously calculated the intensities for one or two convolutions, 

 I then calculated the number of convolutions for this case. 

 Then we have E = M, consequently the number of the requi- 

 site convolutions = oyVtt = ^'^' ^ '^ok therefore at first 

 9 convolutions, then 10; in both cases the needle remained 

 stationary ; but at 1 1, it immediately turned back very quickly. 



It results at the same time from the above, that if the con- 

 necting wire pass through the magnetic meridian, the needle 

 can never be repelled at 90°; for in this case, according to the 

 equation (A'), we shall have 



E= tang. 90° ^/(a* + l)M; 

 but as tang. 90° =00, then the magnetic power of the con- 

 necting wire should be infinitely great, therefore (he magnetic 

 power of the earth ought to be =0. 



Vol. G2. No. 308. Dec. 1823. 



3 L XCIII. Su'T. 



