135

a—3

shaly rock was removed until a hard bearing was obtained for the timbers, and the timbering was completed from the surface of the ground to the excavated depth. " Water is the engineers' most troublesome enemy, and the conversion of this subtle foe into a barrier of defence is a triumph of engineering as effective as it is novel. This process can be applied to excavations for bridge piers, to tunnels, and to other general work of a difficult and expensive character, as well as to shafts. But in shaft work alone it should be invaluable, as by it numerous valuable deposits of coal and other minerals, now inaccessible on account of overlying strata of water-bearing materials, can be reached, as in the case of the Chapin mines, and in those Balgian coal-mines which first led Mr. Poetsch to launch upon the engineering world his startling but very efficient process." Annexed is a sketch-plan showing the process of sinking. (See page 136.)

Mudie's Quartz-crushing and Amalgamating Machine. In reference to this machine Mr. E. B. Meekison, Inspector of Machinery for the Victorian Government, in his official report, states : " On the 15th of January I inspected, at Elaine Mudie's crushing, amalgamating, and gold-saving machine, and beg to submit the following report: The machine consists of a cast-iron trough 3ft. wide, lined with boiler-plate, where the rollers work. It is divided into partitions into three divisions; in each of these a roller 2ft. in diameter and 12in. wide works. There is a fall from each division to the other one, as shown on the plans. The method of working is as follows : The quartz is first broken small, and then fed into the first division. In this part there is a quicksilver-well, into which the quartz drops, and from there passes under the first roller, where it is crushed to a size. That will allow it to pass through the grating fixed in the division into the second compartment, where it is crushed finer, and then passes through a punched grating with two hundred holes to the square inch, also fixed to a division ; it then flows into the quicksilver-well, lined with amalgamated copper-plate ; from there it passes under the third roller, and is still further ground, and then flows over another silver-well, also lined with amalgamated plates, and from this it flows over a short table and discharged. " The machine, at my first visit, was driven by a horse, and after it was taken out I tried to turn the gear and found I could easily drive the machine. The speed was fifty-four oscillations per minute, and the distance it oscillated was Bin. " Mr. Mudie informed me that the day before my visit he crushed five trucks of quartz in eight hours. These, I consider, would hold over a ton. Taking this as an average I think this small machine working continuously would crush 18 tons of ore per week. " There is no pump used, as the water was brought in pipes from a dam on a higher level. The machine requires very little fixing, and can easily be erected without any skilled labour, and I think it would be suitable for parties of miners, especially in outlying districts, and with reasonable care there is very little chance of breakages. "I think the machine could be improved by putting rings of hematitic iron on the rollers (wedged with wood). These could easily be renewed instead of having to provide new rollers. With these rings there would be no wear on the rollers. It would also improve the gold-saving properties of the machine if the crushed material, after it left the machine, had to pass over quicksilver and blanket tables. Any fine gold that might pass the ripples would likely be caught on these tables." With reference to the weight and cost of the medium, the Parkes Independent newspaper of the 15th December last gives the following: " The entire weight of a plant capable of crushing 50 tons of quartz per week does not exceed 5} tons ; and the foundations and setting are said to be so simple that, if furnished with materials, any intelligent miner can put the whole of the machinery in position in a day. The motive force required to work a crusher of the capacity indicated is a twohorse power engine; indeed, for some time the one erected at Elaine was worked by means of one horse and a common horseworks, but this motive force was found not to be regular enough for the purpose. The cost of a plant to crush 50 tons per week is estimated at £200 to £250. Mr. C. Coote, of 172, William Street, Melbourne, showed us a plan of the machine and described its workings. He also exhibited some of the stone operated upon and a sample of the tailings; the first of these being solid quartz, and the latter were of a satisfactory degree of fineness. To us the invention appears invaluable; for it is what may almost be termed a portable crushing-plant, yet working as cheaply and effectively as the intricate and cumbrous machinery now employed to extract gold from quartz, and on this account is specially suitable for erection on fields which, from

being more or less untried, do not warrant a large expenditure m the erection of a large crushing plant." Sutherland's Concentrator and Classifier. 4\ very simple contrivance was patented last year by Mr. George Sutherland, of Melbourne, for concentrating and classifying metalliferous product's. The appliance is so simple and cheap that it deserves attention. It is stated by the patentee that a machine to treat two tons of ore per hour only costs from £45 to £55. The following description and remarks on this machine are taken from the Australian Mining Standard : — " A glance at the illustrations indicating the general principles of Sutherland's concentrator will show at once to what an extent it is a new departure in the interesting and very important problem of mechanical separation of metalliferous minerals from their gangue. In the first sketch given herewith is shown the general idea of an experiment, which may be tried very easily by any one who is desirous of testing the main principle for himself. Let the crushed ore be graded according to size by means of two sieves, of which the coarser has holes not more than, say,