100

Class 1 .— MINING AND MINERAL PRODUCTS.South Side—Areas S. 1 to S. 27.

[United

Hogar pipe; this was about four feet in length, madeof leather, and stiffened by rings of metal; the constantdamage this was liable to in blasting caused it to bealmost abandoned, and in its place the stock and slidepipe was introduced. This consists of two cast-iron pipessliding into each other as a telescope, and kept tight inthe joint by a stuffing-box: this contrivance is not onlyexpensive in first cost, but liable to breakage and heavyto handle. Both these modes of pumping are subject toa still greater defect; the pump can only be made nearlyunder the pump trees, so that during a long time of thesinking, it often occurs that only two or three men canbe effectually employed in the shaft: this, in some of thelarge shafts (say, in a common size used in South Wales,18 feet by 10 feet) causes serious delay to the progress ofthe work.

In boring, it has been customary to use a borer, thebody of which was made of wrought iron, and the bit orend of the borer of shear steel welded on to the iron.No attempt appears ever to have been made to fix anydefinite proportion between the size of the stock or handleand the breadth of the bit: and from this cause a verygreat portion of the power of the striker has been uselesslyexpended.

The use of cast-steel borers is, in some respects, en-tirely new as applied to mining, and by the superiorhardness of cast steel as compared with shear steel, greatlyexpedite the process of boring, and save expense; theyhave also an advantage in transmitting the force of thehammer to the bit, on account of their stiffness or rigidity;

and, further, to prevent loss of power, it is of importancethat the bit should be so proportioned to the handle orstock as to work freely in the bore-hole, and at thesame time, spring or bend as little as possible under theblow of the hammer. The following proportions appearto answer these conditions:—

Diameter of

Breadth of

Octagon Cast Steel.

Face of Bit.

1 inch.

li inch.

n „

if »

i± ,,

2 „

„

2£ ..

H „

2£ „

The suction-pipe now used by the exhibitor is about 20feet in length, is made of gutta percha, and supersedes theuse of the leather Hogar, and stock and slide: it is notliable to accident, and can be repaired easily; it enablesthe pump-hole to be made in any part of the shaft, and agreater number of men to work in the shaft at one time.

The introduction of electricity as the power for blastingin connection with the improvements before explained, maybe said to constitute a new era in the history of mining.

The apparatus at present used for blasting is a Grove’sbattery of six inches square: this is placed in some con-venient position near the top of the shaft: two copperwires, coated with gutta percha, are carried down theshaft, and these are connected to other wires inserted ina small cartridge which is placed in the charge of powderfor blasting; the cartridges are formed thus—

c, /, are two thin copper wires covered with gutta percha,and twisted together at <], g, to any length required, ac-cording to the depth of the hole; 6 is a piece of woodplaced to separate the wires to the distance of aboutT^ths of an inch apart, so that the fine platinum wire in-serted and soldered into the copper at a shall not beliable to be broken in tamping, or otherwise injured ; andfurther to guard against this, a thin case or tube of pine

wood is tied over the wire and distance piece of wood atc, d, and the platinum wire covered with fine powder,the end of the tube secured at h by paper covering, andthe whole case varnished over with a solution of shellacin naphtha. This plan of preparing the cartridge isfound by experience very certain and effective; butmany other modes can be easily used to obtain the sameend.

l f ig. 1.

Fig. 2.

-a

Let fig. 1 be the section, and fig. 2 the plan of a shaft incourse of sinking. Let d, d, d, d, be the wires leading tothe electric battery, then at a, c, a, is shown the manner

in which the holes are placed to first penetrate a streamof rock (or “ enter it” as termed by miners) : where onehole only can be fired, the difficulty and delay of entering