46 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXVIII.) 
to tlie magnetic axis or parallel to it ; i. e. whether the wires in moving, formed a 
band which moved edgeways or flat ways ; the results were the same as with the four 
wires close together, so as to represent, as far as they could, a round or square wire. 
3141 . From all these results it may be concluded, that the current or amount of 
electricity evolved in the wire moving amongst the lines of force, is not, simply, as the 
space occupied by its breadth correspondent to the direction of the line of force, which 
has relation to the polarity of the power, nor by that width or dimension of it which 
includes the number or amount of the lines of force, and which, corresponding to 
the direction of the motion, has relation to the equatorial condition of the lines ; 
but is jointly as the compound ratio of the two, or as the mass of the moving wire. 
The power acts just as well on the interior portions of the wire as on the exterior or 
superficial portions, and a central particle, surrounded on all sides by copper, is just 
in the same relation to the force as those which, being superficial, have air next them 
on one side. 
3142 . By immersing the poles of the magnet in different media, and then making 
comparative experiments with the same copper wire loop ( 3145 .), it was found that 
the amount of the induced current was the same in air, water, alcohol and oil of tur- 
pentine. The experiments in air were repeated between those with the liquids, so as 
to give a very consistent and safe result as to the equality of action in all the cases. 
3143 . The effect of variation of substance the next subject which seemed to 
me important to bring under investigation, because it has a direct relation to the 
amount of force exerted, or ready to be exerted, wdthin solid bodies, at any distance 
from the magnet, in situations and under circumstances where it was absolutely im- 
possible to apply the vibrations of a magnetic needle, or any other form of the effects 
of attractive and repulsive forces. The interior of such bodies as iron, copper, bis- 
muth, mercury, &c., including the most paramagnetic and the most diamagnetic, 
seemed, in this way, open to experimental investigation, both as to the amount of 
lines of force traversing them under various circumstances, and also as to the direc- 
tion of the lines or their polarity. 
3144 . In an early series of these Researches*, experiments bearing upon this sub- 
ject are described ( 205 - 213 .). Wires of different metals were moved across the lines 
of force of a magnet, and the result arrived at was, that the currents induced in these 
different bodies were proportional to their electro-conducting power ( 202 . 213 .). 
3145 . The thick wire galvanometer ( 3123 .), with its good and short conducting 
communications, promised however better results, and therefore loops like those 
already described of copper wire ( 3133 .), were prepared with wires of different metals, 
all of the same diameter, namely, 0’04 of an inch, being only -^th of the substance 
of the conducting and galvanometer wire. The metals were copper, silver, iron, tin, 
* Philosophical Transactions, 1832, pp. 179-182. 
