tering minutely into
these exceptions, it will be sufficient to show that all abstract truth
is entirely excluded from reward under this system. It is only the
application of principles to common life which can be thus rewarded.
A few instances may perhaps render this position more evident. The
principle of the hydrostatic paradox was known as a speculative truth
in the time of Stevinus; [About the year 1600] and its application to
raising heavy weights has long been stated in elementary treatises on
natural philosophy, as well as constantly exhibited in lectures. Yet, it
may fairly be regarded as a mere abstract principle, until the late Mr.
Bramah, by substituting a pump instead of the smaller column, converted
it into a most valuable and powerful engine.--The principle of the
convertibility of the centres of oscillation and suspension in the
pendulum, discovered by Huygens more than a century and a half ago,
remained, until within these few years, a sterile, though most elegant
proposition; when, after being hinted at by Prony, and distinctly
pointed out by Bonenberger, it was employed by Captain Kater as the
foundation of a most convenient practical method of determining the
length of the pendulum.--The interval which separated the discovery, by
Dr. Black, of latent heat, from the beautiful and successful application
of it to the steam engine, was comparatively short; but it required the
efforts of two minds; and both were of the highest order.--The influence
of electricity in producing decompositions, although of inestimable
value as an instrument of discovery in chemical inquiries, can hardly be
said to have been applied to the practical purposes of life, until the
same powerful genius which detected the principle, applied it, by
a singular felicity of reasoning, to arrest the corrosion of the
copper-sheathing of vessels. That admirably connected chain of
reasoning, the truth of which is confirmed by its very failure as a
remedy, will probably at some future day supply, by its successful
application, a new proof of the position we are endeavouring to
establish.

[I am authorised in stating, that this was regarded by Laplace as the
greatest of Sir Humphry Davy's discoveries. It did not fail in producing
the effect foreseen by Sir H. Davy,--the preventing the corrosion of
the copper; but it failed as a cure of the evil, by producing one of an
OPPOSITE character; either by preserving too perfectly from decay the
sur