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LENZ ON ELECTRO-MAGNETISM. 617 
I soon perceived that from this none but false results could be ob- 
tained. By considerably widening the circuit of the spiral, it advanced 
nearer and nearer to the upper bow of the magnet ; so that by removing 
the armature, not only the sudden disappearance of the magnetism 
in it, but also the sudden removal which took place at the same 
time from that upper part of the magnet (the bay of the horseshoe) 
acts on the spirals, and indeed unequally with unequal diameters of 
the spiral ; the electromotive power becomes thus greater in larger 
spirals than it would otherwise be. On this account I took two strong 
rectilinear magnetic systems, each of which consisted of ten single 
magnet bars ; I laid them with their opposite poles against one another 
so that they lay in a straight direction, and brought the iron cylinder 
which had served me in the above-mentioned experiments as an arma- 
ture to the horseshoe magnet, between their poles, while the spirals 
covered the cylinder ; upon this L let the magnet be suddenly drawn 
by two assistants from each other in opposite directions. 
I wound at first ten convolutions of wire No. 2 round the iron cy- 
linder, 
the diameter of the convolutions = 0°73 inch; 
upon this I wound ten convolutions of wire No. 2 round a wooden 
dise, 
the diameter of the convolutions = 6°57 inches ; 
the wooden disc was perforated in the centre, into which the iron cy- 
linder was inserted. The observation gave 
Angle of Deviation. 
Mean. 
1 2 3 4 
Narrow Conv. 946 | 27:1 96°4| 26°5 | 26°15 
Wider Con- JOBE DOT" 199-0) 1) DOB NWN D9-5O 
volutions. { 23°4: I3°5 21°6 93°9 22°92 
Narrow Conv. | 24:8 | 27°7 | 26°3 96°6 | 26°35 
I observed the deviation of the wider spirais between the narrower, 
in order that the fault which might have originated by diminishing the 
magnetic power of the magnet systems might be estimated : we there- 
fore have 
for the narrower spirals the angle of deviation a = 26°95 
for the wider spirals the angle of deviation a! = 22°71 
The length of the wire of the multiplier and of the conducting wires 
(reduced to the diameter of the first) was as in the former experiments, 
i.e. they amounted together to 673°25, or L + 1 = 67325, A however 
is for the narrower convolutions = 28, and for the wider A! = 203. 
