Electro-Magnetism, as a Moving Power. , Se 
powers be not more than sufficient to compensate for the loss ; 
third, the power of a machine does not in ith its velocity. 
The second general rule is, that integrity of the conducting 
and magnetizing wires, is of the utmost consequence. By integ- - 
rity, I mean not only entire absence of flaws, fractures, and im- 
perfectly soldered joints, but a perfect molecular arrangement. 
Bending or twisting a wire, impairs its conducting power ; and a 
wire which has once anon wound upon a magnet, is not fit for 
- same purpose agai 
 Fhird.—Iit is well jai that the fepulsive power i is not equal 
to the attractive, of the same magnet, be it even of the hardest 
steel. The difference between the two forces is still greater in 
electro-magnets, and for the same reason. ‘There is also another 
cause which operates to diminish the repulsive forces of electro- 
magnets, which will be considered when treating of the influence 
of secondary currents. 
_ Fourth.—T wo SETS aK unequally charged, attract each 
other, even when similar are presented. The same is true 
of the steel magnets, but not to so great an extent. 
Fifth.—Change of poles‘cannot be introduced in a machine, 
for the following reasons: 1. It requires time; and during this 
time, the magnets which change poles, are ditiacsod and re- 
tained somewhat by those which do not change. 2. Similar 
poles will attract and produce back action ; for, unless the mag- 
nets which change poles be favored by excess of battery, or 
superior conductors, they cannot receive near the same charge, as 
those which do not change: for, first, there is magnetism of an 
opposite character to be overcome ; and secondly, two breaks in 
or circuit are necessary to produce change of poles. 
"Pwo magnets which have a statical repelling power, that is, 
yer which will merely keep them asunder when the machine 
is at rest, will attract each other when the machine is in motion. 
This singular fact is a consequence of secondary currents, shortly 
to be described. 
The next law to be observed is, that the sum of the forces of 
any number of magnets charged by one battery, is in a diminish- 
ing ratio to the forces of one magnet charged by the same bat- 
tery, provided the battery be not in excess. Hence there must 
bea Breat loss of power, when a number of magnets are ee 
