108 Mr. Wilde — Researches in Magnetism and Electricity . [Apr. 26, 



strict accordance with the principle of conservation, yet they are, at the 

 same time, contrary to the inferences which are generally drawn from 

 analogical reasonings, and to some of those maxims which philosophers 

 propound for the consideration of others. 



The author directs attention to some new and paradoxical phenomena 

 arising out of Faraday's important discovery of magneto-electric induction, 

 the close consideration of which has resulted in the discovery of a means of 

 producing dynamic electricity in quantities unattainable by any apparatus 

 hitherto constructed. He has found that an indefinitely small amount of 

 magnetism, or of dynamic electricity, is capable of inducing an indefinitely 

 large amount of magnetism, — and again, that an indefinitely small amount 

 of dynamic electricity, or of magnetism, is capable of evolving an in- 

 definitely large amount of dynamic electricity. 



The apparatus with which the experiments were made consisted of a 

 compound hollow cylinder of brass and iron, termed by the author a 

 magnet-cylinder, the internal diameter of which was 1|^ inch. On this 

 cylinder could be placed, at pleasure, one or more permanent horseshoe 

 magnets. Each of these permanent magnets weighed about 1 lb., and 

 would sustain a weight of about 10 lbs. An armature was made to revolve 

 rapidly in the interior of the cylinder, in close proximity to its sides, but 

 without touching. Around this armature 163 feet of insulated copper 

 wire was coiled, 0'03 of an inch in diameter, and the free ends of the wire 

 were connected with a commutator fixed upon the armature-axis, for the 

 purpose of taking the alternating waves of electricity from the machine in 

 one direction only. The direct current of electricity was then transmitted 

 through the coils of a tangent galvanometer ; and as each additional magnet 

 was placed upon the magnet-cylinder, it was found that the quantity of 

 electricity generated in the coils of the armature was very nearly in direct 

 proportion to the number of magnets on the cylinder. 



Experiments were then made for the purpose of ascertaining what rela- 

 tion existed between the sustaining-power of the permanent magnets on the 

 magnet-cylinder, and that of an electro-magnet excited by the electricity 

 derived from the armature. 



When four permanent magnets capable of sustaining collectively a 

 weight of 40 lbs. were placed upon the cylinder, and when the submagnet 

 was placed in metallic contact with the poles of the electro-magnet, a 

 weight of 1/8 lbs. was required to separate them. With a larger electro- 

 magnet a weight of not less than 1080 lbs. was required to overcome the 

 attractive force of the electro-magnet, or twenty-seven times the weight 

 which the four permanent magnets used in exciting it were collectively 

 able to sustain. It was further found that this great difference between 

 the power of a permanent magnet and that of an electro-magnet excited 

 through its agency might be indefinitely increased. 



Experiments were then made with electro-magnets of various sizes, for 

 the purpose of ascertaining the cause of these paradoxical results. 



