the fewer the magnets and the s 
limits,) the greater the ratio of mecha 
experience as this appears dianoiirtegill 
cient to prove the experiment infeasible. 
are such as have been incident to the prosecution of all inventions 
in-their early stages. It is much to be regretted, that in our coun+ 
try the invention should be a subject of mercenary-speculation, 
when in reality it has no value exce tas an experiment, and that 
the public have been so far mislec withdraw that counte- 
er ! periment really merits. 
We can not but deplore, that such an teresting branch of science 
should > epee and that the very name of electro-maghet- | 
ism should be coupled with empiricism. 
There can be no doubt in the mind of any one who may have 
seen an electro-magnetic engine, that-it furnishes a mechanical 
power already eagurornee and. useful to a certain extent, provided 
: er be not expensive and difficult. 
r cannot be expensive, if the mechan- 
} a7 cob Pistso 6 of the aggregate attractive force ; that 
this a does not hold in any of the plans of which, hitherto, we 
have had any description, I shall prove, when the cause comes to 
be considered. Yet in certain arrangements this law must ob- 
tain, and although the necessary construction be at present some- 
what complicated, yet ultimately it doubtless will be simplified. 
“At ga we have no means of computing the extent of mag- 
at 
: care, I have succeeded in producing an attractive force 
€ 0) pounds, by a galvanic pair having only ten square 
es of zinc exposed ; whereas with the usual arrangements, it 
required two or three square feet to produce the same power. 
This power, though so great for the means used, yet probably 
was not near the maximum procurable from the same zinc sur- 
face. It would seem, then, that if the above mentioned ratio ex- 
ists in attainable forms of machines, the application of the power 
cannot be otherwise than cheap. The difficulty of maintaining 
a uniform power is by no@neans insurmountable. The faults 
hitherto have been, the wearing and alloying of the pole-changer 
