104 MR. H. WILDE ON A PROPERTY OF 



small magneto -electric or electro-magnetic machine is 

 sufficient to excite the great electromagnet of the lo-inch 

 machine ; and it has been further f ound^ by my friend 

 Mr. Gr. C. Lowe^ that the current from one small machine 

 is sufficient to excite simultaneously the electromagnets 

 of several small machines. In a number of 3i-inch ma- 

 chines which have been constructed under my direction 

 for Messrs. Elkington and Co.^ for the electrodeposition 

 of copper on a large scale^ the currents from two 3|-inch 

 electro -magnetic machines are made to excite the electro- 

 magnets of twenty similar-sized machines to a degree 

 sufficient to bring out the maximum dynamic effect of 

 each machine. The electromagnets of the two 3i-inch 

 exciting machines are charged by the current from a small 

 2f-inch magneto-electric machine; but I have found that 

 nearly as good a result may be obtained from the twenty 

 machines by dispensing with the small magneto-electric 

 machine, and employing the residual magnetism of the 

 two 3f-inch exciting machines in a manner similar to that 

 described, almost simultaneously^ by Mr. Farmer"^, Messrs 

 Varleyt, Mr. Siemens J, and Sir Charles Wheatstone§. 



So far I have adverted principally to the means by 

 which a very serious defect in the practical working of the 

 new induction machine was remedied, a defect which many 

 of my friends, who were unacquainted with the efforts 

 which have been made to overcome it, have considered to 

 be fatal to the success of what seemed likely to be a use- 

 ful invention. But while the difficulty arising from the 



* Letter to the Author, November 2, 1S66, Salem, Mass. U.S., Proceed- 

 ings of the Literary and Philosophical Society of Manchester, February 19, 

 1867. 



t Specification filed at the Office of the Commissioner of Patents, Decem- 

 ber 24, 1866. 



I Specification filed at the Office of the Commissioner of Patents, Janu- 

 ary 31, 1867. 



I Proceedings of the Koyal Society, February 14, 1867. 



