ic force of the pile is therefore limited to
the extent of the chemical affinity, and in the case before us is
obtained by the combination of the zinc and sulphuric acid. In the
combustion of coal, the heat results from, and is measured by, the
affinity of the oxygen of the atmosphere for that substance.

It is true that with a very small expense of zinc, we can make an
iron wire a magnet capable of sustaining a thousand pounds weight of
iron; let us not allow ourselves to be misled by this. Such a magnet
could not raise a single pound weight of iron two inches, and
therefore could not impart motion. The magnet acts like a rock,
which while at rest presses with a weight of a thousand pounds upon
a basis; it is like an inclosed lake, without an outlet and without
a fall. But it may be said, we have, by mechanical arrangements,
given it an outlet and a fall. True; and this must be regarded as a
great triumph of mechanics; and I believe it is susceptible of
further improvements, by which greater force may be obtained. But
with every conceivable advantage of mechanism, no one will dispute
that one pound of coal, under the boiler of a steam-engine, will
give motion to a mass several hundred times greater than a pound of
zinc in the galvanic pile.

Our experience of the employment of electro-magnetism as a motory
power is, however, too recent to enable us to foresee the ultimate
results of contrivances to apply it; and, therefore, those who have
devoted themselves to solve the problem of its application should
not be discouraged, inasmuch as it would undoubtedly be a most
important achievement to supersede the steam-engine, and thus escape
the danger of railroads, even at double their expense.

Professor Weber of Gottingen has thrown out a suggestion, that if a
contrivance could be devised to enable us to convert at will the
wheels of the steam-carriage into magnets, we should be enabled to
ascend and descend acclivities with great facility. This notion may
ultimately be, to a certain extent, realised.

The employment of the galvanic pile as a motory power, however,
must, like every other contrivance, depend upon the question of its
relative economy: probably some time hence it may so far succeed as
to be adopted in certain favourable localities; it may stand in the
same relation to steam power as the manufacture of beet sugar bears
to that of cane, or as the production of gas from oils and resins to
that from mineral co