﻿54 Mr. H.Wilde on a Property of the Magneto-electric Current. 



x-y. 

 190-5 



188-5 



x+y. 

 167-0 

 1640 

 160-0 



x—y. 

 185-5 

 1890 



Mean . . 



for x-y= 188-4. 

 this we get 



163-7 





x + y = 67'3, %-y = 42'6, ,2? = 54-95, y = 12*35, and - =4-45. 



The electromotive force is equal to that of 44'5 elements. 



From the last two experiments it follows that the electromo- 

 tive force is independent of the distance between the knobs b 

 and d. As is at once seen, y represents the conducting-power in 

 the entire circuit ; and this depends principally on the conduct- 

 ing-power in the sparks at/ and g, and on their number. In ex- 

 periment 25, y was almost twice as great as in experiment 26. 

 Yet this is easily explained if we consider that the sparks in the 

 first case followed each other much more rapidly than in the latter. 



The subject I have here undertaken to treat is by no means 

 completely exhausted by the experiments adduced. Several 

 questions which are in the closest connexion with it require fur- 

 ther investigation. It is only after these questions have been 

 answered that it can be settled whether the electromotive force 

 may in the future find a practical application. 



VIII. On a Property of the Magneto-electric Current to control and 

 render Synchronous the Rotations of the Armatures of a number 

 of Electromagnetic Induction Machines. By H. Wilde, Esq.* 



THE discovery of the property which I am about to describe 

 arose out of the efforts which have been made, during the 

 last two years, to reduce the internal heat generated in an electro- 

 magnetic machine by the induction-currents set up in the elec- 

 tromagnet and armature by the rapid magnetization and demag- 

 netization of the latter. This heating of the armature (as is well 

 known) was first observed by Dr. Joule in 1843, as the result of 

 a delicate investigation on the quantitative relation existing be- 

 tween ordinary mechanical power and heatf- In the electro- 

 magnetic machines of my invention this phenomenon unfortu- 

 nately manifests itself on an alarming scale, so much so that 

 the armature of the 10-inch machine rises in the course of a few 

 hours to 300° F. and upwards ; and were the action of the ma- 

 chine to be continued for any lengthened period, the insulation 

 of the armature-coils would be in great danger of being destroyed. 



* Communicated by the Author, having been read at a Meeting of the 

 Literarv and Philosophical Society of Manchester, December 15, 1868. 



t Phil. Mag. S. 3. vol. xxiii. p.' 264. 



