e quantity
magnet, may, in a less degree, be obtained by substituting for them one
large wire; but in this case, on account of the greater obliquity of the
spires and other causes, the magnetic effect would be less. In
accordance with these principles, the receiving magnet, or that which is
introduced into the long circuit, consists of a horseshoe magnet
surrounded with many hundred turns of a single long wire, and is
operated with a battery of from twelve to twenty-four elements or more,
while in the local circuit it is customary to employ a battery of one or
two elements with a much thicker wire and fewer turns.

It will, I think, be evident to the impartial reader that these were
improvements in the electro-magnet, which first rendered it adequate to
the transmission of mechanical power to a distance; and had I omitted
all allusion to the telegraph in my paper, the conscientious historian
of science would have awarded me some credit, however small might have
been the advance which I made. Arago and Sturgeon, in the accounts of
their experiments, make no mention of the telegraph, and yet their names
always have been and will be associated with the invention. I briefly,
however, called attention to the fact of the applicability of my
experiments to the construction of the telegraph; but not being familiar
with the history of the attempts made in regard to this invention, I
called it "Barlow's project," while I ought to have stated that Mr.
Barlow's investigation merely tended to disprove the possibility of a
telegraph.

I did not refer exclusively to the needle telegraph when, in my paper, I
stated that the _magnetic_ action of a current from a trough is at least
not sensibly diminished by passing through a long wire. This is evident
from the fact that the immediate experiment from which this deduction
was made was by means of an electro-magnet and not by means of a needle
galvanometer.

[Illustration: Fig. 7]

At the conclusion of the series of experiments which I described in
_Silliman's Journal_, there were two applications of the electro-magnet
in my mind: one the production of a machine to be moved by
electro-magnetism, and the other the transmission of or calling into
action power at a distance. The first was carried into execution in the
construction of the machine described in _Silliman's Journal_, vol. xx,
1831, and for the purpose of experimenting in regard to the second, I
arranged around one of the upp