LENZ ON ELECTRO-MAGNETISM. 619 
periments as from those of Biot, that the action of a particle of the 
electric currents which encircle the magnet upon every particle of 
~ the spiral, is in the inverse ratio of the squares of the distance. 
It also immediately follows from the law just demonstrated that the 
electric current produced in the various wire rings which inclose 
the armature, by its removal from the magnet, is in the inverse ratio of 
the diameter of the rings; for the electromotive power is the same in 
every ring, but the resistance it suffers in being conducted increases as 
the diameter of the rings; therefore the electric current, the quotient 
of the electromotive power, by the resistance it suffers, decreases as the 
diameter of the rings increases. 
III. Influence of the Thickness of the Wire of the Electromotive Spirals 
on the Electromotive Power produced in them. 
I have also again made these experiments with the horseshoe mag- 
net, since in this case the convolutions of the wires had always the same 
magnitude. I here employed ten convolutions, which I formed from 
the wires No. 1, No.3, and No.4, and in which the diagonals were in 
the same proportion as the numbers 233 : 839: 1661. The entire 
length of the convolutions in each sort was $3 inches. The deviations 
are contained in the following table. 
Angle of deviation. 
es irmacstesMerienies stenueencet OEM Mean. 
1 Be 3 4 
Spirals \ 39°3| 40°4] 35°1 | 37°8 | 38°15 \ 38:19 
from No. 1. 39°3 | 40°4| 35:2 | 38°8 | 38°22 
Spirals \ 36°8 | 39°6| 40°2 | 42:0 | 39°65 \ 39°60 
from No. 3. 36°4| 39°4| 40°4} 42°0 | 39°55 
Spirals \ 40°5 | 42°4| 37°5 | 39°3 | 39°92 \ 39°74 
from No. 4. 40°3 | 40:4] 37°5 | 40:1 | 39°57 
Spirals \ 38°6 | 40°6 | 35°7 | 37°8 | 38°17 \ 38-00 
from No. 1. 38°7| 40:0 | 35:2] 37°4| 37°82 
If we now combine the observations No. 1, at the beginning and end 
of the series of experiments; and take their mean, we have the following 
deviations : 
For No. 1 the deviation or a = 38°l, 
— No.3 or a’! = 39°6, 
BONO. ihe = oni Beas 
‘From the proportion of the diagonals in which that of the wire of the 
multiplier is expressed by 274, we find the following reduced lengths 
(referred to the wire of the multiplier or No. 2) of our three spirals, 
