74 Henry Riddelt on 



of the permanent magnets, precisely as if surrounded by a helix 

 and a current passed in the proper direction, and in either case 

 the motion would cease. 



This idea has been very common duiing the past two 

 centuries. 



In the Belfast (Central Library can be seen full series of the 

 " Gentleman^ s Magazine " and the " Annual Register,'^ and a 

 study of these will well rejjay any person having leisure t(j consult 

 them. In the " Genthman's Magazine^'' of 175 1 a device similar 

 to this is mentioned, while in the same journal of 18 18 there is 

 described a motion by John Spence, using a "black substance" 

 as. insulator to cut off the magnetic influence. It was said that 

 the machine had been in operation for several years, and in the 

 " Yorkshire Gazette" of 1821 we read of it as still in motion. 

 The ''Gentleman's Magazine^' says: — "We trust this ingenious 

 man will meet with the encouragement he deserves — if not as the 

 reward of his talents and perseverance, at least for the benefit of 

 the community, for it is from such sources that great national 

 improvements often arise." 



The earlier inventors, however, were not troubled with any 

 insulators. They presented the magnets boldly at the proper 

 angle, they said, to the steel projections on the face of the wheel 

 and, if we are to believe them, immediately obtained motion of a 

 rotary character, powerful and continuous, The earliest example 

 I have found in the work of John Taisner, published I think in 

 1579, in which he describes a hollow rim or wheel of silver with a 

 loadstone shaped like a truncated cone. The interior of the rim 

 was set with small pieces of steel which the loadstone attracted. 

 Apparently the inventor had some knowledge of the repulsive as 

 well as of the attractive forces of a magnet, and concluded that as 

 the steel pieces were attracted by the pole presented towards 

 them, as soon as they passed this pole they were repelled by 

 the other. Taisner says, " neyther can continual motion be found 

 by any other meanes than by the stone magnes in this manner," 



About seventy or eighty years later Wilkin speaks in the 

 book already mentioned of the magnetic power. He tells us that 



