Many of the most calamitous explosions in collieries have been clearly traced to the ignition of the fire-damp through the firing of shots ; and in a still largei number of cases there has been much presumptive evidence of the same cause hav ing existed, although absolute proof was wanting. The Mining Journal of London, from which we extract the substance of the present article, refers, as a corroboration of this statement, to the Edmunds Main Colliery explosion, which, it will be recollected, resulted in the loss of 60 lives, and which actually occurred through the blasting operations ; and at the Oaks colliery, only a few miles from it, where some 334 were killed, and in regard to which, little doubt is entertained by practical men that it was to the firing of the shot at the steps to the back vmrkings, that the fearfu casualty was due. Now, that the ???T of gunpowder does very much facilitate mining operations, is beyond question—the power is easily applied in the desired position, and the amount of work done with a given expenditure of manual labor is sufficiently large to satisfy the workmen. But, valuable as blasting agents are, in ordinary cases, it can be readily understood that, to explode gunpowder in the immediate neighborhood oi so explosive a gas as that of fire-damp is, to say the least, anything but a safe operation, more especially when conducted, as it is in coal mining, in a comparatively small and inclosed area, from which escape ispractically impossible. It cannot, therefore, be surprising that the desirability of abolishing the use of gunpowder in coal mining should have been aclsnowiedged, or that so competent an authority as Mr. Geo. Elliot, M. P., for Durham, in his excellent address to the North of England Institute of Mining Engineers, should have pointed to the discovery of a means of superseding gunpowder in collieries as one of the most important that could be made. Messrs. Jones and Bidder, oi England, have made an invention, illustrated in the accompanying engraving, intended for breaking down coal, slate, and other minerals, without the use of powder. Instead of the usual blast, two or more ?vedges are caused to be driven consecutively ty hydraulic or screw power between the surfaces of the substances to be broken down. The arrangement of apparatus for this purpose may be variously modified, but by preference they employ apparatus constructed as follows : Two tension-bars or rods, either formed of two separate pieces or of one looped piece, lire inserted into the hole cut in the coal or other sub-stiuioo, the outer ends of which bars are connected to the cylinder of a hydraulic ram or press, or to the framing, or screwed nut or boss carrying a screw spindle. Between the tension-bars, at their innermost end, is placed a clearance-box, and then two metal pressing blocks, between which is afterwards forced first a single wedge by the action of the ram of the hydraulic press, or of the screw spindle ; the ram or screw spindle is then withdrawn, and a second wedge is inserted, either between the eaie side of the first wedge and that of one of the pressing blocks, or the first wedge may be made as a split wedge, and the second wedge be driven between the two parts thereof. If requisite, a third wedge may, in like manner, be driven in, and so on until a sufficient wedging action is obtained to effect the breaking down of the mass desired to bo removed. The wedges and pressing blocks maybe formed cither so as to cause the pressing blocks while expanding to retain at first a position parallel to each other by making these ?vith inner inclined surfaces, similar to the inclined surfaces of the wedges, or they may be arranged so as to form from the commencement a gradually increasing angle with each other. The wedges can pass beyond the pressing blocks and into the clearance box, wliich thus allows them to impart a greater lateral motion to the pressing blocks than would be the case were the clearance box not employed ; it may, however, in some cases be dispensed with when no great lateral motion is required. The ends of the tension bars are by preference made detachable from the hydraulic press for introducing the ?vodg?S consecutively. When the apparatus is worked by hydraulic power they prefer to construct the hydraulic press with the force-pump formed in one therewith or fixed directly thereto, and it may be constructed either with a closed receptacle containing the requisite charge of water for working it, or the water may be supplied through a suction pipe from a separate reservoir. This arrangement of apparatus may also be employed in some cases with effect with one wedge only, as by forming the pressing blocks parallel—that is, without inclined surfaces corresponding to those of the wedge, as heretofore proposed—they are enabled to obtain an expansion equal to the entire thickness of the wedge, instead of equal only to a small portion thereof, as would otherwise be the case. I'he advantages claimed for the improved apparatus, in addition to the absence of the noxious vapors in the mine and the danger resulting from the use of blasting powder are— first, a great saving in the time employed in effecting the hrcaking down of the coal or other material, owing to the almost unlimited power which is available by their system, enabling them to break down at one operation far greater masses than can be effected by blasting ; and, secondly, the avoidance of the great deterioration of the coal or other mineral ?vhich takes place when blasting powder is used, owing to the large quantities of small fragments or " slack "' which are produced thereby. In the annexed diagrams. Fig. 1 shows a part sectional side elevation of the apparatus ; Fig. 2 shows a plan of the same ; and Pigs. 3 to 8 show details to an enlarged scale. Similar letters of reference indicate similar parts in each of the figures. A A are the tension bars of wrought iron, steel, or other metal capable of withstanding considerable tensional strain. These bars may either be formed of one piece bent round at a so as to form a loop, or they may be two separate bars connected together at t. These bars are inserted into a hole cut in the coal or other mineral, B, to be broken down in the manner shown, the ends thereof, which project beyond the face of the mineral, being widened out for the reception of the cylinder, D, of the hydraulic press between them, to which they are connected by Theads formed at their extremities, being made to catch against lugs, c c, on a collar, C, secured to the cylinder. Before the tension bars are placed in the hole a clearance box, E, is first placed between them at the extreme end of the loop, after which the two pressing blocks, ? ?, are inserted, the sectional form of which blocks is shown more clearly at the enlarged section of Fig. 3 ; lastly, the two wedges, or the double or split wedge, G G, Shown enlarged at Fig. 6, arc introdnoed botweeu the br(", A A, so that their points just enter the small interstice between the pressing blocka The parts A, E, P, and. G thus put together are then inserted into the hole in the material, B, and the hydraulic press, D, is connected to the bars, A A, as above described. Th press, D, has a plunger, d (P, the front part, (Z, of which projects between the tension bars,' A A, as shown, and is formed either as shown in enlarged cross section at Pig. 4, or as at Pig. 5. To the back end of the press, D, is fixed the pump, H, worked by means of the handle, L, and inclosed in the reservoir, 1, containing the water required for working the press. The press being put in action the plunger forces the double wedge G forward between the pressing blocks, P, thereby forcing these asunder in an angular direction, and, consequently, causing them to exert a powerful bursting strain upon the sides of the hole. By forming the inner surfaces of the pressing blocks inclined, corresponding more or less with the taper of the wedge, this first expansion of the blocks may be effected in a more or less parallel direction instead of angular. The object of the clearance box is to allow of the points of the wedges being driven past the inner ends of the pressing blocks, so as to effect an increased expansion of these ends ; where this is not required the clearance box may be dispensed with. The double wedge, G, having been driven into the required extent, the press is detached from the tension bars, A A, which is effected by first opening a passage of communication llptween the reservoir, I, and cylinder, D, by means of the screw, J, so as to allow the water to flow from the latter back into the former, after which the press is pushed forward slightly, so as to release the T-heads of the tension bars from the lugs, c, whereupon the tension bars are sprung open and the press removed. Another wedge, G', shown enlarged at Pig. 7, is now placed between the tension-bars, A A, so that its point fits into the space, g (Fig. 6), formed between the two parts of the double wedge, G. To facilitate the correct insertion of the wedge, for this purpose a handle, ? (Pig. 8) is screwed into the rear end thereof, which is removed when the wedge is in position. The press is then again attached to the tension bars, and the wedge, G', is forced in between the two parts of the double wedge, thereby effecting a still greater expansion of the pressing blocks ; and in like manner one or more other wedges may be consecji-tively forced in, as indicated at Figure 3, xmtil the accumulated pressure thus produced is sufficient to break down the mass of coal or other material operated upon. The invention can also be modified so as to employ screw instead of hydraulic power. The arrangement of the tension bars and pressinsf blocks is similar to that used with hydraulic power ; but the hydraulic press is replaced by a frame wherein is a slot with a worm wheel in it, fitting with a female screw thread upon a screw spindle formed with flat upper and lower surfaces, and passing through correspondingly-formed holes in the bosses of the frame, so that it can move through but cannot turn in the latter. In gear with the wormwheel is the worm, the spindle of which is carried by brackets on the frame, the ends of the spindle being formed to receive a ratchet lever for rotating the same. The ends of the tension-bars are formed with lugs, which catch behind keys bearing against other lugs formed on the frame, so that the frame is by this means connected to and disconnected from the frame by merely inserting the keys, and without having to spring open the tension bars. As the projecting ends of the tension bar may thus be made considerably shorter than in the previously-described arrangement, this mode of connecting the tension bars might with advantage be employed in that case also. By rotating the worm wheel by means of the worm the screw spindle is advanced, and is caused to force the wedge between the pressing blocks, as in the hydraulic arrangement Messrs. Jones and Bidder do not limit themselves to the precise details described, as these may, of course, be variously modified without departing from the nature of the invention. Thus, for instance, where only one wedge requires to be driven in, the arrangement may be reversed—that is, the wedge may be placed at the inner end of the tension bars, with its point facing the pressing blocks situated at the front end, and which are then forced in by the press so as to cause the wedge to enter between them, or the wedge might, in that case, be drawn forward by the press against the pressing blocks ; but what they specially claim is—first, the construction and employment of apparatus ibr breaking down coal, slate, stone, and other minerals, wherein two or more wedges are caused to be driven consecutively by hydraulic or screw power between the surfaces of the material to be broken down, in such manner that the pressure exerted at one and the same point can thereby be increased at will ; and, secondly, the arrangement of tension bars connected in a readily detachable manner to an hydraulic press or frame carrying a screw spindle, operating in combination with pressing blocks and one or more wedges. Sinqriilar Case of lOisoning by a Fly. We learn from the Troy Press that Captain Green, of that city, Deputy Inspector of Boilers and Assistant Engineer of the Fire Department about a fortnight since (August 35), was bitten by a common horse fly, which had been feeding on carriole, and had communicated the poison. The wound was on his right hand, between the thumb and index finger, and he soon experienced considerable pain,which gradually increased. The bite was at first supposed to be from a mosquito, and treated accordingly by a druggist, and afterwards by a physician. The pain and swelling continued to increase, and erysipelas setting in, a surgeon was consulted and pronounced it a bite by a fly. Medical treatment has succeeded in placing Mr. Green out of danger, but it will be a long tJmo before he can roCflver the wee of his arm.