The principle of the press which bears the name of Bramah,
was known about a century and a half before the machine, to which
it gave rise, existed; but the imperfect state of mechanical art
in the time of the discoverer, would have effectually deterred
him, if the application of it had occurred to his mind, from
attempting to employ it in practice as an instrument for exerting
force.
These considerations prove the propriety of repeating, at the
termination of intervals during which the art of making machinery
has received any great improvement, the trails of methods which,
although founded upon just principles, had previously failed.
325. When the drawings of a machine have been properly made,
and the parts have been well executed, and even when the work it
produces possesses all the qualities which were anticipated,
still the invention may fail; that is, it may fail of being
brought into general practice. This will most frequently arise
from the circumstance of its producing its work at a greater
expense than that at which it can be made by other methods.
326. Whenever the new, or improved machine, is intended to
become the basis of a manufacture, it is essentially requisite
that the whole expense attending its operations should be fully
considered before its construction is undertaken.
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