motion is indicated by the arrow. The carriages, C C, are traversed by
screws, V V, which are fixed between the columns. The extremity, v, of
the axle of the pulley to the right is threaded, and actuates a
helicoidal wheel, E, which transmits motion to the wheel, R, through the
intermedium of the vertical shaft, F. This transmission, completed by the
wheels, R R, and the pitch-chains, G G, is designed to move the saw
vertically, through the simultaneous shifting of the carriages, C C. A
tension weight, P, through the intermedium of pulleys, D_{1} D_{1},
permits of keeping the saw taut. A reservoir, H, at the upper part of the
frame, B B, contains the water and sand necessary for sawing. The feeding
is effected by means of a rubber tube, I, terminating in a flattened
rose, J, which is situated over the aperture made by the saw. A small
pump, L. over the reservoir takes water from K, and raises it to H. The
sand is put in by hand.

Above the basin, K, a system of rails and ties supports the carriage, Q,
upon which is placed the block of stone to be sawn. When one operation
has been finished, and it is desired to begin another, it is necessary to
raise the pulley-carriers and the saw. In order to do this quickly, there
is provided a special transmission, M, which is actuated by hand, through
a winch.

The work done by this saw is effected more rapidly than by the ordinary
processes, and certain very hard rocks, usually regarded as almost
intractable, can be sawed at the rate of from one to one and a half
inches per hour.

[Illustration: FIG. 4.--APPARATUS FOR SAWING STONE INTO SLABS.]

For sawing marble into slabs of all thicknesses, the arrangement
described above may be replaced by a system consisting of two drums
having several channels to receive as many saws, or two corresponding
series of channeled pulleys, b b (Fig. 4), independent of each other, but
keyed to the same axles, i i. When the pulleys have been properly spaced
by means of keys, the whole affair is rendered solid by a bolt, g. The
extremity of the axles forms a nut into which pass vertical screws, c c.
These latter are connected above with cone-wheels, l l, which, gearing
with bevel wheels keyed to the shafts, e, secure a complete
interdependence of the whole. The ascending motion, which is controlled
by the endless screws, f, and the helicoidal wheels, m, is in this way
effected with great regularity. Uprights, a a, of double T-iron, fixed to
joists,