340 



FRENCH EXHIBITION. 



water can be pumped out and the sinking com- 

 menced in the common way. Such is the bare 

 outline of the method. Concrete (beton) may 

 have to be run in behind the tubbing, and many 

 other modifications adopted for insuring a per- 

 fect separation between the water in the pit and 

 the world of water outside. 



In 1860 a signal success was attained by M. 

 Chaudron in sinking an air-shaft at Peronnes, 

 where the watery beds had extended from the 

 43d metre to 105 metres deep ; and M. de Vaux, 

 Inspector-General under the Belgian Govern- 

 ment, reported in 1861 that the work was ex- 

 ecuted for less than a quarter of what it would 

 have cost under the ordinary method. 



A very ingenious addition of M. Chaudron's 

 is a shield or diaphragm of sheet-iron tempora- 

 rily fixed near the bottom of the tubbing and 

 having a large pipe or equilibrium-tube in the 

 centre, in which the water can rise, and through 

 which the boring-rod passes down, having ex- 

 panding arms which open out below the shield 

 and excavate the ground. By this means the 

 weight of the tubbing, which at Peronnes was 

 about 88 tons, was so balanced as to throw only 

 about 19 tons upon the rods employed for its 

 suspension. 



At St. Avoid, two pits have been thus tri- 

 umphantly sunk, of which the sections are ex- 

 hibited. One through 426 feet of permeable 

 red sandstone, grfo vosgien ; the final wedging- 

 curb was fixed at 523 feet deep, on May 1, 1866, 

 and coal was found on April 4th, last, at 1,036 

 feet. The second pit was so far complete that 

 the " moss-box " was successfully laid, on Feb- 

 ruary 3d, last, at the depth of 521 feet. 



In the application of steam machinery, to 

 supersede hard labor in the miner's daily task 

 of boring holes for firing charges of gun- 

 powder, there are in the Exhibition two or 

 three inventions which have passed the ordeal 

 of practice, and have actually been employed in 

 the daily service of mines. Since M. Sommeil- 

 ler's successful application of single borers, each 

 driven from its own cylinder by compressed air 

 acting on a piston, a number of modifications 

 of his general arrangement have been proposed. 



M. Doering, of Euhrort, in Westphalia, 

 mounts his machine on a horizontal arm pro- 

 jecting from a heavy iron carriage, which can 

 be run to and fro on the rails in the level or 

 gallery. The machine itself, consisting of a 

 double-acting cylinder with piston, is, by means 

 of pivoting and the motion of the horizontal 

 arm up and down a vertical standard, capable 

 of being set in any direction and at any height 

 required. The drill, or borer, is attached by a 

 key to the piston-rod, and is then by the action 

 of compressed air projected and withdrawn sev- 

 eral hundred times a minute against and from 

 the surface of the rock, being turned through a 

 small angle after every blow. A jet of water is 

 constantly squirting into the hole for the re- 

 moval of the debris. lu the great zinc-mines 

 of Moresnet, 11 of these machines, 3 of them 

 on the newer construction, have been in actual 



use there ; and in a level in strong dolomitic 

 rock, where they used to drive by hand-labor 

 1| metres in 14 days, they have with the machine 

 made an advance of 3 metres and sometimes 

 even 4 metres in the same time, and with only 

 two men instead of six. 



The stand for the "Bergborr maskin" of M. 

 Bergstrom is a strong bar, with steel point 

 at the bottom, and steeled holders regulated by 

 a screw at the top ; and as the boring cylinder 

 traverses up and down the bar, this latter must 

 be fixed by the aid of cross-timber, in a direc- 

 tion parallel to that of the intended bore-hole. 

 The drill is then made to act by compressed air 

 in a manner generally similar to the last. The 

 weight of the whole apparatus is only 120 Ibs. 

 The very machine exhibited is stated to have 

 worked for 700 days under-ground, and to have 

 bored 1,000 metres. Upon hard granite it .has 

 bored 2 metres in the hour. 



A third modification of this general type is 

 the machine exhibited by General Haupt, an 

 American. It is mounted between two upright 

 bars, whicli are fixed between floor and roof. 

 The movement of the piston and drill is effected 

 by steam. The valve arrangements are very 

 ingenious, and the moderate size and weight 

 of the apparatus are in its favor. 



A very beautiful horizontal cylinder-engine 

 is exhibited by M. de la Roche Tolay, engineer 

 of the Chemin do Fer du Midi, intended to bore 

 the rock by a rapidly-rotating drill forced for- 

 ward by hydraulic pressure of about 1,540 Ibs. 

 Various forms of cutting-drill have been ex- 

 perimented npon, but the only one which ap- 

 pears to have given good result in hard rock is 

 the diamond-mounted ring of M. Leschot. The 

 boring implement is tubular, and admits a jet 

 of water through the middle into the hole ; its 

 face, of soft irou, is studded with eight pieces 

 of black diamond, carefully hammered up ; and 

 the incomparable hardness of the adamant en- 

 counters with such success the hardest materi- 

 als of common rock, that the engineer states 

 the cost of the abrasion of diamond for a hole 

 of half a metre deep to be under twopence. 



The tunnelling machine, by Captains Beau- 

 mont and Locock, R. E., is a heavy powerful 

 means of projecting against the face of the rock 

 a disk armed at its circumference with thirty- 

 six borers, which, gradually turned with the 

 disk, cut an annular groove, whilst a central 

 borer at the same time drills a hole of equal 

 depth, which is afterward to be charged with 

 powder and fired. 



The machine of the Steam Stone-cutting Com- 

 pany, of New York, consists of a carriage of 5 

 feet in width, carrying on both sides a series 

 of vertical bars armed with cutters which notch 

 out a groove of the required depth instead of its 

 being cut by the picks of the quarry-men. 



Coal-cutting Machines. The earliest suc- 

 cessful machine is the pick-machine of Messrs. 

 Firth and Donisthorpe, worked by compressed 

 air. Two of them have been daily at work at 

 Hetton, for upward of four years. Two newer 



