616 LENZ ON ELECTRO-MAGNETISM. 
Number of Deviations. Mean Devia- 
Convolutions. TPS EP eT tions or a. 
1 2 3 4 
5 86 | 87] 85| 86 8°63 
10 17-5 | 17°81 17-2} 17-1 17°40 
15 264 | 27-2 | 266 | 25-6 26°45 
20 35°5 | 35:3 | 356 | 346] 35:25 
25 452 | 460 | 45°0 | 442} 45:10 
30 546 | 565 | 55:0 | 541 55°05 
Hence may be calculated by means of the least squares 
—& = 1°73 and log. sin.  § = 8°18478 
therefore we have for the calculated values of a 
a 
Wimiber of?! sg) ae ts ee Difference. 
Convolutions. | Calculated.|Observed. 
5 8°77 8°60 + Sir 
10 17°60 17°40 + 0°20 
15 26°53 16°45 + 0:08 
20 35°58 35°25 + 0:33 
25 45°00 45°10 — 010° 
30 54°67 55°05 — 0°38 
Here then the coincidence for this kind of experiments is very great, 
so that we may regard the position as entirely confirmed, namely that 
“ the electromotive power which the magnet produces in a spiral, 
with convolutions of equal magnitude and with a wire of equal thick- 
ness and like substance, is directly in the same proportion as the num- 
ber of the convolutions.” 
Moreover, we must not let it escape our attention, that in all the three 
' series of observations the differences of the calculated and of the ob- 
served deviations are in the beginning positive, and then negative; 
which seems to show that the electromotive power increases in a some- 
what quicker proportion than the number of the convolutions; but the 
differences are so small, and become, when the observations are made 
with great care (as the third series proves) smaller and smaller, 
I therefore ascribe this little irregularity to the influence of some pecu- 
liar circumstance which up to the present moment I have not succeeded 
in discovering. 
II. On the Influence of the Distance of the Convolutions of Spirals 
on the production of the Electromotive Power in them. 
In these experiments I employed at first the horseshoe magnet, but 
