Electro-Magnetism, as a Moving Power. Beal 
the battery current in proportion to its velocity ; whereas the ap- 
plication of mechanical force to drive the machine against its 
own motion, contributes to the magnetizing power of the bat- 
tery. ‘The same rule applies to the motion of repelling poles. 
When two repelling electro-magnets are made to approach each 
other, a recession of the magnetic forces takes place, and conse- 
quently a secondary current is developed flowing in the direction 
of the battery current. While the forces are thus kept in re- 
tirement, if _ two magnets be made to recede, they will again 
rmine wards the poles, and tian the secon- 
s Seti, ) in which, the secondary current may be so ap- 
s to diminish or accelerate the velocity of the revolving 
par. 
~ It will now be readily seen, that two electro-magnets, with a sta- 
tical repelling power sufficient to keep them asunder, would cease 
to repel when the machine is in motion. The attractive forces 
constitute the paramount motive power, and when the velocity 
of the machine exceeds that which the repulsive powers alone 
would give it, they ate of no value whatever, unless they ope- 
rate in conjunction with attractive forces; but even where this is 
the case, the secondary current arising from the velocity of the 
machine, must occasion so great a disparity between the similar 
poles of the magnets which change and those which do not 
change, that attraction, in lieu of repulsion, must take place. 
I have thus endeavored to point out the most important of 
those difficulties in the way of the application of this power, 
which necessarily arise from the connexion of galvanism and 
magnetism. There are many other hindrances entirely of a me- 
— nature, which perseverance will doubtless overcome, 
