262 Electro-Magnetic Apparatus and Experiments. 



arrangement for a reciprocating electro-magnetic engine, there 

 being no change of poles, as the motion is effected by an ar- 

 rangement shown in the two next figures. This form of en- 

 gine will be described in a future article. 



Revolving Armature. 



Figure 5, represents an instrument invented in February, 1838, 

 for exhibiting motion by magnetism without change of poles. 



Figure 5. 



This instrument was the foundation of a series of experiments, 

 made with reference to the mechanical application of magnetism, 

 which will be published with drawings in a future communica- 



