6 Electro-Magnetic Machine. 
within the attracting distance, that is, the distance at which the iron 
was attracted to the magnet; by measurement, it was found that the 
steel magnet attracted the iron one inch and one fourth. A galvanic 
magnet was next used of the same lifting power, and consequently of 
much less weight; the attracting distance of this magnet was found — 
to be one inch and three fourths, shewing a material gain in favor of 
the galvanic magnet. Mr. Slade inquires, “ has Mr. Ritchie’s mag- 
net been so constructed as to give a favorable trial to this principle ?”* 
Mr. Davenport informs me that each increase in the number of wires 
has been attended with an increase of power. 
Conclusions. 
weibecdt appears then, from the facts stated above, that electro-mag- 
netism is quite adequate to the generation of rotary motion. 
2. That it is not necessary to employ permanent magnets in any 
part of the construction, and that electro-magnets are far preferable, 
not only for the moving but for the stationary parts of the machine. 
gee Dy the power. generated by electro-magnetism may be indefi- 
r prolonged, since, for exhausted acids, and corroded metals, 
resh pa aa batteries, kept always in readiness, may be substituted, 
even without stopping the movement. 
4. That the power may be increased beyond any limit hitherto 
attained, and probably beyond any which can be with certainty assign- 
ed,—since, by increasing all the members of the apparatus, due ref- 
erence being had to the relative proportionate weight, size, and form 
of the fixed and movable parts—to the length of the insulated wires 
and the manner of winding them—and to the proper size and con- 
struction of the battery, as well as to the nature and strength of the 
acid or other exciting agent, and the mamner of connecting the battery 
with the machine, it would appear certain, that the power must be 
increased in some ratio which experience must ascertain. 
5. As electro-magnetism has been experimentally proved. to be 
sufficient to raise and sustain several thousands of pounds, no reason 
can be discovered why, when the acting surfaces are, by skillful me- 
chanism, brought as near as possible, without contact, the continued 
exertion of the power should not generate a continued rotary move- 
ofits: ganas 
* This question I am not able to answer, as I have not seen any account of the 
apparatus or of the experiment, but only of the result. 
