New Rock Drill.

Cromwell Argus, Volume V, Issue 258, 8 September 1874, Page 7

New Rock Drill.

(From the Mining World, May 16.)

The present is eminently an age of progress. Inventive genius has been brought to bear on all departments of Industry. In none has this been more conspicuous than in engineering. The efforts of human labour have been aided and in some cases superseded by mechanical appliances which have rendered possible undertakings of a nature and magnitude otherwise out of the question. Among the most valuable aids to the civil engineer in his many difficult tasks, are the various rock drills which have been invented at different periods. Of all those now in existence none possesses the many advantages of the Diamond Rock Drill. Employing the hardest, though the most expensive, substance known as the active agent of its operations, it cuts with facility through all kinds of material. The expense of the diamond points is the chief obstacle to the general adoption of this machine. A new invention which furnishes cutters of equal hardness has just been made by Mr Macintosh, the well-known engineer. It consists of small points in chilled iron or steel, which are poured when molten into iron moulds, where temperature has been reduced to the lowest attainable point. The metal being in veiy small quantities sufficient to form sharp cutting nibs is thus cooled almost instantaneously, and a degree of hardness attained which is equal, if not superior, to that of the diamond. An illustration of this may be seen in the little wheel which has been constructed to cut glass, and which has been found to answer this purpose as well as the diamond in previous use. No substances, in fact, possess greater cutting properties than chilled metals, and this is particularly the case with iron or steel. A great advantage of this system is that the points be cast of the form required, and made so as to fit into the sockets which are prepared for their reception in the drill.- The value of this invention is not confined to simple boring operations, though in them it can scarcely be over-esti-mated. By fixing the nibs to a strip of metal a saw for stone can be constructed, which will answer all the purposes of the diamond pointed stone saws used in California. Planing machinery for stone may also be made by arranging the joints in such a manner that they will produce a' level surface. The method of fixing the nibs is proposed to be such that as soon as they shall become blunted —a thing not likely to occur until after long use, though they may be accidentally broken —it will be perfectly simple to replace those destroyed at a moment's notice. The great practical advantages which are likely to result from., this principle are not over-esti-mated. In coal-cutting machines the wearing and destruction of the knives will be entirely obviated. Points fitted into either circular wheels or to endless- bands, according to the plan adopted in the Gartsherrie machine, would be practically indestructible. It will thus be seeir that the .most /valuable-

results may bo exported tc flow from this intention. , cwiwuwiuj.

"Inall the OBilal rock driflsj with the «r----oeption of the Drummond drift, effect is] produced by a series of sh<>cksv -"'The rock is thus gradually pounded away, and a hole made to the required depth. To any one at all acquainted with the principles of mede*f thatriflith efoh pe|r tions of the instrument. As' the J drill is drawn back after the stroke is given it impinges on the spring, which turns round the drill, and here again is another suock to the more delicate parts of the machine*- "JPhginr jury which is thus done is, however, TrifllngV compared with the immense loss of power which is entaUedMjhe reciprocating action. Bach time f ,tha>< fresh operationiß undertaken,' and the force which had accomplished the previous blow and produced its effect is allowed to go to waste. Where action is continuous no loss of force takes place, the amount requisite for, performing the work being alone expended. This the Diamond Rock Drill, with its regular and increasing motion, most fully accomplishes, and its simple machinery of an oscillating engine, acting on a spurwheel; gearing into a pinion to which the'drill-rod is attached, reduces the friction to the smallest amount. By the new invention all this ad-mirable-adaption .of force ..will he secured,, and the advantages of the Diambid Drill attained without its attendant heavy expenditure. Another and"peculiar feature" which" gives the most decided superiority Co" the Diamond over all other .known kinds of drills is the. possibility of distinguishing exactly the various strata through which It passes by the core furnished. In the ease of drills of the common description this is impossible; the rock or'mineral traversed is pounded.'; Any judgment of |bs quality must be learned from the dust which may be extracted at great depths ; it is> of course, impossible to ascertain with any degree of correctness the nature of the material passed through ; and it is thus impossible to acquire a knowledge of the greatest importance in mining operations which, with the Diamond Drill, is at once presented in the core cut out by the machine. Information of this nature is not alone valuable to the miner—it is equally so to the engineer who is making a tunnel. On Mr Macintosh's system, where the chilled points are to replace the Diamond Drill, the ence consistc in the substitution Of the points of metal for those of the precious stone used in the former.

Tn estimating the importance of any invention, it is often difficult to grasp the ; many consequences which may appear from first, sight a small change. The perforations which we have hitherto been, accustomed to Bee made by the diamond drill are comparatively small. The great expense attaching to the instrument, and the danger of-destroying the valuable stones which, are the cutting tools, makes the size of the drill a matter of serious consequence, In the chilled points there is no such difficulty. Their cost.is insignificant, and there is no reason why they might not be fitted to the edges of discs of such size as to open up at once a tunnel or gallery of any required size. Such an idea may at first sight appear preposterous ; but as dimensions have no part in science, which regards objects irrespective of their magnitude, there is no reason why so desirable an end might not be accomplished. Another most Valuable use to which such drills may be turned is in boring for coal or other minerals. An' instrument of the kind might be sunk to any required depth, no matter what is the nature of the material through which it may have to pass, as the loss of a few points would be a matter of no consequence. In colliery operations we have always insisted on the many benefits which must arise from the introduction of coal cutting machinery. The compressed air used to drive these machines is not only of the greatest utility in assisting to keep up a healthy ventilation, but as only a few attendants are required instead of the many hewers and others why are at present employed, the consumption of air is reduced to the smallest amount. A human being respiring and working requires to have several hundred cubic feet of air to supply his wants during eight or nine hours. To furnish the. amount thus abstracted requires a system of ventilation often difficult to carry out at great depths, where a number of workmen are regularly employed. A coal-cutting machine driven by air furnishes a supply for the wants of all those employed in directing its amount to materially purify the wh»le atmosphere, and to overcome the many nauseous vapours which emanate from the earth in such positions. It may not be out of place to mention that the air used as a motive power in such machines having been much compressed, necessatily gives out its coloric, and when freed descends to a very low temperature, thus cooling the workings where the heat is usually oppressive to the men. For such machines, the point* invented by Mr Macintosh will be of the greatest utility, as they will be in reality' everlasting. It is a well known fact that a lead wheel if driven with sufficient velocity, will cut through a bar of steel, and in the case of the drill with its chilled bits driven at a considerable velocity, no material, however hard, will be able to resist its action. The invention is, indeed, of such great importance that the inventor may say with Horace, '* Exegi monumentum aerc permnius."