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, D squared and D cubed, 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, D cubed, 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.

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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 the safety and strength of roburite, as compared with gun cotton, dynamite, and blasting gelatine.  The results were conclusive of the great power of the new explosive, and so far fully confirmed the reports of the able mining engineer and the chemical experts who had been sent to Germany to make full inquiries.  These gentlemen had ample opportunity of seeing roburite used in the coal mines of Westphalia, and it was mainly upon their testimony that the patents for the British empire were acquired by the Roburite Explosive Company.