64 Mr. H. Wilde on the Indefinite Quantitative 



railway trains ; also in the shaping of materials by cutting 

 and abrasive processes, where the heat of friction is 

 induced by manual power multiplied through lever 

 arrangements and the expenditure of mechanical force. 



(III.) That definite quantities of magnetic and electric 

 force hold each other in equilibrium is an axiomatic 

 proposition recognised by every student of physical 

 science, and is amply demonstrated in a variety of 

 instruments for the measurement of these forces. 



That quantities of magnetism or electricity indefinitely 

 small will induce quantities of these forces indefinitely 

 great is an antithetical proposition which, not many years 

 ago, would have been justly regarded as absurd. I have 

 demonstrated elsewhere* the truth of this proposition by 

 showing that a small magneto-electric machine, easily 

 turned by hand, will generate an indefinitely large amount 

 of magnetism in an electro-magnet, and induce an amount 

 of electricity in an armature, revolving by steam or other 

 motive power, sufficient to fuse rods of the most refractory 

 metals, and to light up a great city with the electric light. 



The most simple illustration of the principle of the 

 indefinite increase of the physical forces from quantities 

 indefinitely small, is shown in Plate II., Fig. 3, where the 

 short arm of a lever presses, through the intervention of 

 an iron segment, against the periphery of a wheel, also of 

 iron, revolving against it. With a constant velocity of the 

 wheel it will be evident that the amount of heat generated 

 at the rubbing surfaces will increase with the distance from 

 the fulcrum of the weight or force on the long arm of the 

 lever, and, if the length of the lever be increased indefinitely, 

 the amount of heat generated will be indefinitely great. 

 If, now, the iron segment constitute the pole of a powerful 

 electro-magnet excited by the current from a magneto- 



* Proc. Roy. Soc, Vol. XV. (1866) ; Phil. Trans., Vol. CLVII. (1867). 



