material to be worked. It passes around the pulleys, P and P', which
are each encircled by a wide and stout band of rubber to cause the
blade to adhere, and which are likewise provided with two flanges. Of
the latter, the upper one is cast in a piece with the pulley, and the
lower one is formed of sections of a circle connected by screws. The
pulley, P, is fast, and carries along the saw; the other, P', is
loose, and its hub is provided with a bronze socket (Figs. 1 and 4).
It is through this second pulley that the blade is given the desired
tension, and to this effect its axle is forged with a small disk
adjusted in a frame and traversed by a screw, _d'_, which is
maneuvered through a hand wheel. The extremities of the crosspieces, D
and D', are provided with brass sockets through which the pieces slide
up and down the columns, with slight friction, under the action of the
vertical screws, _g_ and _g'_, within the columns.

A rotary motion is communicated to the four screws simultaneously by
the transmission arranged upon the frame. To this effect, the pulley,
P, which receives the motion and transmits it to the saw, has its
axle, _f_, prolonged, and grooved throughout its length in order that
it may always be carried along, whatever be the place it occupies, by
the hollow shaft, F, which is provided at the upper extremity with a
bevel wheel and two keys placed at the level of the bronze collars of
its support, G. The slider, D, is cast in a piece with the pillow
block that supports the shaft, _f_, and the bronze bushing of this
pillow block is arranged to receive a shoulder and an annular
projection, both forged with the shaft and designed to carry it, as
well as the pulley, P, keyed to its extremity. Now the latter, by its
weight, exerts a pressure which determines a sensible friction upon
the bushing through this shoulder and projection, and, in order to
diminish the same, the bushing is continuously moistened with a