He puts this into a hole in a
small stake-iron immediately under a hammer which is connected
with a treadle, and has a die sunk in its surface corresponding
to the intended form of the head; and having given one part of
the form to the head with the small hammer in his hand, he moves
the treadle with his foot, disengages the other hammer, and
completes the figure of the head; the returning stroke produced
by the movement of the treadle striking the finished nail out of
the hole in which it was retained. Without this substitution of
his foot for another hand, the workman would, probably, be
obliged to heat the nails twice over.
14. Another, though fortunately a less general substitution
of tools for human hands, is used to assist the labour of those
who are deprived by nature, or by accident, of some of their
limbs. Those who have had an opportunity of examining the
beautiful contrivances for the manufacture of shoes by machinery,
which we owe to the fertile invention of Mr Brunel, must have
noticed many instances in which the workmen were enabled to
execute their task with precision, although labouring under the
disadvantages of the loss of an arm or leg.
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