110 Mr Barlow on the Laws of Electro-Magnetic Action. 
Mean Deflection in the 'preceding Table., reduced to one Stand- 
ard Power of the Battery^ viz. A 
Length 
of 
Distance of Wire ^ Inch. 
Distance of Wire 14 Inch. 
Observed 
Mean oh- 
Reduced to 
Observed 
Mean ob- 
Reduced to 
Wire. 
Standard 
served De- 
Standard 
Standard 
served De- 
Standard 
Power. 
flection. 
A = 21°. 
Power. 
flection. 
A =31°. ' 
838 
O 
21 
0 / 
4 55 
4 55 
798 
24 
6 18 
5 26 
758 
25 
8 12 
6 46 
718 
25 
8 50 
7 17 
678 
26 
9 10 
7 4 
638 
254 
10 32 
8 31 
598 
26 
10 20 
8 10 
558 
26 
10 30 
8 17 
518 
29 
12 10 
8 30 
478 
30 
13 0 
8 44 
438 
30 
14 10 
9 31 
0 
O / 
0 / 
398 
30| 
14 25 
9 25 
31 
3 20 
3 20 
358 
314 
15 10 
9 38 
314 
3 47 
3 43 
318 
34 
17 0 
9 52 
35 
4 5 
3 31 
278 
34 
17 15 
10 1 
36 
4 25 
3 39 
238 
35 
18 20 
10 18 
34 
5 20 
4 45 
198 
33| 
18 55 
11 8 
34 
5 25 
4 49 
158 
344 
21 25 
12 21 
35 
6 35 
4 30 
118 
334 
23 5 
13 53 
34 
7 35 
6 46 
98 
324 
24 40 
15 37 
32 
8 32 
8 13 
Although in these reduced results there are a few discrepan- 
cies, some of the numbers being less where they ought to be 
greater than the preceding ; yet these, which may be attributed 
to errors and irregularities in the experiments, are not such as 
to leave any doubt, that, upon a general view of the question, 
there is a certain increase of effect as the wire shortens ; and 
it only remains to ascertain according to what function of the 
length this increase takes place. 
As the tangent of the angle of deflection is the measure of 
the electro-magnetic effect, it is natural to refer to this in prefe- 
rence to any other trigonometrical line ; and, comparing these 
tangents with the lengths, the square root of the latter is the 
most simple function of it which seems to approach towards 
the required ratio, although perhaps the discrepancies are ra- 
ther too great to enable us to say, with confidence, that such is 
the law in question. At the same time, the difficulty in redu- 
cing such observations to numerical results, arising from the va- 
riable power of the battery, and other circumstances, renders it 
