saw, S, passes. In the center of the bed plate, A', which is cast in two pieces connected by bolts, there are ties to which are screwed iron rails, e, which form a railway over which the platform car, E, carrying the stone is made to advance beneath the saw.

The saw consists of an endless band of steel, either smooth or provided with teeth that are spaced according to the nature of the 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 solution of soap and water through the pipe, g, which runs from the reservoir, G'.

The saw is kept from deviating from its course by movable guides placed on the sliders, D and D'. These guides, H and H', each consist of a cast iron box fixed by a nut to the extremity of the arms, h and h', and coupled by crosspieces, j and j', which keep them apart and give the guides the necessary rigidity.

The shaft, m, mounted in pillow blocks fixed to the left extremity of the frame, receives motion from the motor through the pulley, p, at the side of which is mounted the loose pulley, p. This motion is transmitted by the drum, M, and the pulley, L, to the shaft, l, at the other extremity. This latter is provided with a pinion, l', which, through the wheel, F', gives motion to the saw. The shaft, m, likewise controls the upward or downward motion of the saw through the small drums, N and n, and the two pairs of fast and loose pulleys, N' and n'. This shaft, too, transmits motion (a very slow one) to the four screws, g and g', in the interior of the columns, and the nuts of which are affixed to the sliders, D and D'. To this effect, the shaft, q, is provided at its extremities with endless screws that gear with two wheels, q', with helicoidal teeth fixed near the middle of two parallel axes, r, running above the table, B, and terminating in bevel wheels, r', that engage with similar wheels fixed at the end of the screws, g and g'.

The car that carries the block to the saw consists of a strong frame, E, mounted upon four wheels. This frame is provided with a pivot and a circular track for the reception of the cast iron platform, E', which rests thereon through the intermedium of rollers. Between the rails, e, and parallel with them, are fixed two strong screws, e', held by supports that raise them to the bottom of the car frame, so that they can be affixed thereto. When once the car is fastened in this way, the screws are revolved by means of winches, and the block is thus made to advance or recede a sufficient distance to make the lines marked on its surface come exactly opposite the saw blade.

In sawing hard stones, it is necessary, as well known, to keep up a flow of water and fine sand upon the blade in order to increase its friction. Upon two platforms, b, at the extremities of the machine, are fixed the water reservoir, C, and the receptacles, C', containing fine sand or dry pulverized grit stone. As may be seen from Figs. 5 and 6, the bottom of the sand box, C', is conical and terminates in a hopper, T, beneath which is adjusted a slide valve, t, connected with a screw that carries a pulley, T'. By means of this valve, the bottom of the hopper may be opened or closed in such a way as to regulate the flow of the sand at will by acting upon the pulley, T', through a chain, t', passing over the guide pulley, t². A rubber tube, u, which starts from the hopper, runs into a metal pipe, U, that descends to the guide, H, with which it is connected by a collar. Under the latter, this pipe terminates in a sphere containing a small aperture to allow the sand to escape upon an inclined board provided with a flange. At the same time, through the rubber tube, c, coming from the reservoir, C, a stream of water is directed upon the board in order to wet the sand.

As the apparatus with but a single endless saw makes but two kerfs at once, Mr. Auguste has devised an arrangement by means of which several blades may be used, and the work thus be expedited.

Without changing the general arrangements, he replaces the pulleys, P and P', by two half drums, V and V' (Figs. 8, 9, and 10), which are each cast in a piece with the crosspieces, D² and D³, designed to replace D and D', and, like them, sliding up and down the columns, A, of the frame. Motion is transmitted to all the saw blades by a cog wheel, X, keyed to the vertical shaft, f, and gearing with small pinions, x, which are equally distant all around, and which themselves gear with similar pinions forming the radii of a succession of circles concentric with the first. All these pinions are mounted upon axles traversing bronze bearings within the drum, which, to this effect, is provided with slots. The axles of the pinions are prolonged in order to receive rollers, x', surrounded with rubber so as to facilitate, through friction, the motion of all the blades running between them.

The other drum, V', is arranged in the same way, except that it is not cast in a piece with the carriage, D³, but is so adjusted to it that a tension may be exerted upon the blades by means of the screw, d, and its hand wheel.

Through this combination, all the blades are carried along at once in opposite directions and at the same speed.—Publication Industrielle.

ROBURITE, THE NEW EXPLOSIVE.

A series of experiments of great interest and vital importance to colliery owners and all those engaged in mining coal has been carried out during the last ten days in the South Yorkshire coal field. The new mines regulation act provides that any explosible used in coal mines shall either be fired in a water cartridge or be of such a nature that it cannot inflame firedamp. This indeed is the problem which has puzzled many able chemists during the last few years, and which Dr. Roth, of Berlin, claims to have solved with his explosive "roburite." We recently gave a detailed account of trials carried out at the School of Military Engineering, Chatham, to test