1831] WRITINGS OP JOSEPH HENRY. 67 



The motion, here described, is entirely distinct from that 

 produced by the electro-magnetic combination of wires and 

 magnets ; it results directly from the mechanical action of 

 ordinary magnetism : galvanism being only introduced for 

 the purpose of changing the poles. 



My friend, Prof. Green, of Philadelphia, to whom I first 

 exhibited this machine in motion, recommended the substi- 

 tution of galvanic magnets for the two perpendicular steel 

 ones. If an article of this kind was to be constructed on a 

 large scale, this would undoubtedly be the better plan, as 

 magnets of that kind can be made of any required power; 

 but for a small apparatus, intended merely to exhibit the 

 motion, the plan here described is perhaps the most conve- 

 nient. 



