88 



Mr. H. Wilde's Experimental Researches 



between the quantities of electricity derived from the magneto- 

 electric machine and the amount of the attractive force mutually 

 exerted by the electromagnet and the submagnet, the particular 

 experiments, the results of which are given in Tables I. and II., 

 were made simultaneously, the tangent galvanometer at the 

 same time forming part of the same metallic circuit as the 

 electro-helices and the wire surrounding the armature. 



26. Coordinate results, such as are shown in Tables I. and 

 II., were, however, obtained, whether the first and second series 

 of experiments were made either together or separately. 



Table II. 



Number of magnets 

 on cylinder. 



Weight, in ounces, 



required to separate 



submagnet from 



electromagnet. 



Squares of magnetic 

 force of the magnet- 

 cylinder. 



1 

 2 

 3 



4 



2-50 

 11-25 

 2400 

 38-00 



2-50 

 10-00 

 22-50 

 40-00 



27. The results arrived at, as shown in the above Table, are 

 somewhat remarkable, and have amongst themselves a well- 

 defined ratio, such as would hardly have been expected from a 

 bare consideration of the nature of the magnetism of the per- 

 manent magnet; for when one magnet was placed on the 

 cylinder, the weight required to separate the submagnet from 

 the electromagnet was 2*5 ozs. It might therefore have been 

 expected that two magnets placed on the cylinder would have 

 induced a double amount of magnetic force in the electro-magnet, 

 whereas the force required to detach the submagnet was equal 

 to a weight of 1T25 ozs., or was a little more than quadrupled. 

 From a further comparison of the numbers contained in the 

 Table, it will be seen that (within the limits and conditions of 

 these experiments, and after making allowance for a certain degree 

 of imperfection in them) the amount of magnetism induced in 

 the electromagnet, as measured by the weight required to 

 separate the submagnet, is as the square of the inducing mag- 

 netism of the permanent magnets of the electro-magnetic 

 machine. 



28. Experiments were then made for the purpose of ascer- 

 taining to what extent an alteration in the length and section 

 of the wires surrounding the electromagnet would influence the 

 quantity of magnetism induced in it. The electrohelices were 

 therefore coupled up so as to form a single circuit 200 feet in 



