350 Electro Magnetism. 
Arr. XVIIl.—E£lectro Magnetism; by Cuarues G. Pace, M. D., 
ashington, D. C. 
In Vol. xxxv, No. 2, of this Journal, I described a revolving 
armature and mentioned that the plan admitted of enlargement 
only with the alteration of the mode of revolution. I must pre- 
mise here, (as I have heretofore expressed myself,) that I do not 
suppose this power susceptible of infinite increase, and in giving 
these descriptions to the public, Iam only selecting from the mul- 
titude of machines I have constructed, such forms as obviously 
economize a given galvanic power. A number of machines 
wherein the poles of the magnets were changed, and others where 
the poles were not changed, but both systems, the stationary and 
revolving, were rendered magnetic and non magnetic at intervals, 
have been laid aside as not worth describing. Another form 
wherein the magnets were made to revolve and attracted by sta- 
tionary armatures is obviously defective, as will be readily seen by 
referring to figure 3d, and supposing the systems reversed. If the 
armatures were stationary, and the charged magnets revolving, 
the magnets would always be attracted by the nearest armature ; 
consequently the magnets would be charged only during one half 
of a revolution. Figures 1, 2, and 3, are modifications on a large 
scale of the revolving armature described in No. 2, of the last vol- 
ume of this Journal. In figure 1, } b, are two Electro Magnets 
Fig. 1. 
disposed at right angles to each other, and firmly secured to 
wooden pillars. Where it is practicable, the magnets should be 
