this process. By means of this simple contrivance each movement
of the finger, from one side to the other, carries five or six
needles to their proper heap; whereas, in the former method,
frequently only one was moved, and rarely more than two or three
were transported at one movement to their place.

13. Various operations occur in the arts in which the
assistance of an additional hand would be a great convenience to
the workman, and in these cases tools or machines of the simplest
structure come to our aid: vices of different forms, in which the
material to be wrought is firmly grasped by screws, are of this
kind, and are used in almost every workshop; but a more striking
example may be found in the trade of the nail-maker.

Some kinds of nails, such as those used for defending the
soles of coarse shoes, called hobnails, require a particular form
of the head, which is made by the stroke of a die. The workman
holds one end of the rod of iron out of which he forms the nails
in his left hand; with his right hand he hammers the red-hot end
of it into a point, and cutting the proper length almost off,
bends it nearly at a right angle. 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