LENZ ON ELECTKO-MAGNETISM. 



617 



I soon perceived tliat from this none but i'alse 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 I 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 

 disc, 



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 



I observed the deviation of the wider spirals 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 =: 26-25 

 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 -|- / = 673-25, X however 

 is for the narrower convolutions = 28, and for the wider X' = 203. 



