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New Zealand Herald, Volume XII, Issue 4203, 4 May 1875, Page 3

The Bulletin des Science* et Arts, of Poligny (Jura), givea particulars of a curious discovery by Dr. AugusteChevreuse. Hβ has found that on decapitating living cockchafers au hour after they have been feeding, they yield four or five drops of a colouring substance, which varies with the nature of the leaves on which they have been feedinp. ind he has already obtained f urtetn different shades. M. NieliMs, professor of chemistry, M. Preclaire, professor of drawing, and M. Chatelaine, architect, have found that this substaucc may be employed either in mouotintcd drawings, liko Indian ink, sepia, &c, or T.iixe 1 with wattr-coloura, and that it does ;.•">! c l .. inge on exposure to tho light. The t louring substance may be collected ou glass or in shells, in which it may be left to dry, and when required for use it is sufficient to dissolve it in water. When appliod in a thick coat it presents the effect of varnish. Two or three cockchafers suffice for a small water-color drawing.

THK DIAMOND ROCK-BORER. The contents of this articlo should possess much interest to tho generality of our readers: — By means of thi? machine, which is as simple as it is ,~. jiive, examples of the toughest rocks are drawn from the earth just as ae! >se-trier brings out a sample of the commodity it is intended to examine. The cores are perfectly cylindrical, and as they are brought to the surface aud laid in th?ir regular order, furnish witli mathematical exactitude the strata as they exist to the depth tested. And not only this, but the base, say of a sandstone formation, will indicate the exact angle of dip of that particular stratum. Ordiuary boring-rods bring up disintegrated fragments—this implement demonstrates the exact succession, extent, and position of the rocks as they exist. The first and main purpose of the machine is, "the sinking of boreholes for the purpose of testing, or prospecting for minerals." It is also useful for the driving of drifts and tunnels for mining, waterworks, or railways, for sinking shafts, and for tho removal of subaqueous rocks by blasting. The primitive boring process is to give a reciprocating motion to a chisel attached to the end of rods, lengthened as the hole is deepened, the tlrbris being brought up by means of shells or angers. Great ditticuly and risk attend giving even a moderately quick reciprocation to a long column of rods. Attempts have also been made to apply a rotatory motion to steel cutters, but even in soft rock speed has been slow, because no steel can lie got which will withstand the abrading action of the rock. The diamonddrill is in principle distinct from any other system of holing rock, and works by rotation without striking a blow. Its action is rather that of abrading than cutting, and the efTcet is produced by the sheer ditl'orenee of hardness between the diamond and tho rock it is operating upon. Between the hardness of these there is no comparison. If a diamond be kept rotating against sandstone, it would ciit a hole a mile deep before it was seriously worn. If, of this resisting power, proper adv.int.igc be taken, it follows that rock can lie holed without striking blows. This enables machinery of the simplest and most ordiuary character to be used, and escapes the mechanical dillieulty and risk of accident incidental to using powerful machinery iu production of percussive actiou. And the gain increases in piogiesoivo ratio where the cutter is at a great distance (say iu depth) from the source of power. The application of the diamond to lockdrilling is thus worked out. The stones arc set in an annular ring made of steel ; they •ire fastened in by making holes as nearly as possible the size of the diamonds to be set, and then burying them, leaving projecting only the amount necessary to allow the water and iMirU of the cutting to pass ; the metal is then drawn round the diamond, so as to close it in on every side, aud give as large a bearing surface as possible to resist tho teudency of the stone to be forced out. The crown so set is attached to the end of a steel tube, and kept rotating against the rock at some 250 revolutions per minute. Water is supplied through tho hollow of the bar, whence it passes under the cuttiug face of the crown to the surface of the hole between the side of the latter and tho outside of the boring tubes ; the diamonds are thereby kept ceol, and the tit brig from cutting washed awaj. The crown must be kept ]) essed forward with a force depending on the nature of the rock to be cut, varying from 40<.>lb. to 8001b., according to the rate of speed desired.

>>o rock is met with in mining which approaches emery in hardness. Vet a crown which had bored through (actual experiment) Oft. of emery, 10ft. of granite, ami 95ft. of hard sandstone, was, so far as the diamonds were concerned, almost as lit for work as when new. The diamonds used aro not valuable gems, 'but carbonate, which until lately had no commercial value, and was lirst introduced for cutting other diamonds. The solid core, when formed, passes into a core-tube, and is kept from falling out on withdrawing the rods by means of sliding wedges or clips, which allow the core to pass freely up, but prevent its rcturuing. The great advantage claimed for this system of boring consists iu the speed obtained, work being doue in months that formerly took years, and in the precision of knowledge secured by the sample cores of strata.

Tho diamond rock borer has survived the epoch of mere experiment. Karly last year SO machines were either at work or (some) preparing to commence. Hero are a few actual results :—At Girrick ironstone was reached at 902 ft. in 45 working days ; at Moorsholme, 041 ft., accomplished in 4i> days; at Fishburno, coal reached at 434 ft. in 5-1 days ; at Wollaton, 700 ft. accomplished in 4S days ; at Loftus, 040 ft. occupied GO days ; at Ballymena, 55Sft. 42 days; at Chewton, So2ft. 108 days ; and at Beeston, I,ooßft. occupied 140 days. These examples might be greatly multiplied. Mr. A. Brogden, M.l*., iu an interesting lecture (September, 1874) on the Uampsido boring near Borrow, cites a bore at St. l!ecs 1,407 ft. deep, and one at Furness 1,730 ft. deep, completed, iu 14 months. The testimonials given by practical men who have used the diamond-borer, are favourable and numerous.