After this adjustment, if a
thousand boxes are made, no additional care is required; the tool
is always carried up to the stop, and each box will be equally
adapted to every lid. The same identity pervades all the arts of
printing; the impressions from the same block, or the same
copperplate, have a similarity which no labour could produce by
hand. The minutest traces are transferred to all the impressions,
and no omission can arise from the inattention or unskilfulness
of the operator. The steel punch, with which the cardwadding for
a fowling-piece is cut, if it once perform its office with
accuracy, constantly reproduces the same exact circle.
80. The accuracy with which machinery executes its work is,
perhaps, one of its most important advantages: it may, however,
be contended, that a considerable portion of this advantage may
be resolved into saving of time; for it generally happens, that
any improvement in tools increases the quantity of work done in a
given time. Without tools, that is, by the mere efforts of the
human hand, there are, undoubtedly, multitudes of things which it
would be impossible to make.
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