612 LENZ ON ELECTRO-MAGNETISM. 
metal could be perceived except at the ends which served for con- 
necting them. 
I now proceed to the experiments themselves. 
I. On the Influence of the number of Convolutions upon the Electro- 
motive Power produced in them. 
In these experiments I connected the wire No. 3 with the multiplier 
so that the conducting wire and the electromotive spirals were formed 
of one and the same piece; the length of this wire was about fifty feet: 
here however this is of no consequence, as it remained the same in all 
the experiments. The experiments themselves are contained in the 
following table. 
— Te 
INDIVIDUAL DEVIATIONS. 
Side A of the Spiral|Side B of the Spiral) 
to the north pole. to the north pole, | Meandevi-| @ in mi- 
{ Le 
ation, or @. nutes, 2a 
End a of | End 5 of | End a of |} End d of 
Index. Index. Index. Index. 
Number of the 
Convolutions 
— | ———-$ —___ 
57 58 5-3 5-8 5:65 | 5°39" | 2°49’ 
121 | 129 | 1151 | 120 | 1200 | 12 00 6 00 
257 | 258 | 229 | 252 | 24.90 | 24 54 | 12 27 
295 | 301 | 262 | 285 | 9832 | 2819 | 1415 
325 | 333 | 294 | 320 | 31-80 | 31 48 | 15 54 
393 | 409 | 353 | 386 | 3877 | 38 46 | 19 23 
| 488 | 408 | 45-9 | 45-43 | 45 43 | 22 51 
| 509 | 45:0 | 49:0 | 48:55 | 48 38 | 24 16 
557 | 568 | 476 | 523 | 5310 | 53 6 | 26 33 
63:1 | 644 | 541 | 57-8 | 5980 | 59 48 | 29 54 
71:8 | 628 | 666 | 6805 | 68 3 | 34 1 
as 
Sse 
wo 
We 
SMAUPWCOMOPW 
aS 
“I 
= 
From this series of experiments we must now deduce the electromo- 
tive power of the spirals for each number of convolutions, for which 
purpose the following considerations will be of service. 
The action of the electric current in the wire of the multiplier upon 
the magnet needle, is a momentary one, since the current itself exists 
only for a moment; we may therefore consider this action as an im- 
pulse given to the needle, and shall be able to measure its force by the 
velocity which it imparts. But the velocity of the needle at its exit is 
evidently as great as that which it acquires when it springs back to the 
point of exit; it may therefore be expressed (f being constant) by 
A =f ¥ (sin. vers. a) 
where A represents the sought for velocity of the exit; or according 
to what has been above stated, the magnitude of the current in the 
wire of the multiplier, and « the angle of deviation of the needle pro- 
duced by this force. This expression changes however by the sub- 
stitution of 2 sin.? 4} instead of sin. vers. a into the following 
A =p‘sin. 4a 
if we putp=f v 2. 
