THE MOLYNEUX DREDGING MACHINES.

Westport Times, Volume III, Issue 459, 30 January 1869, Page 3

THE MOLYNEUX DREDGING MACHINES.

A. few weeks ago, says the Otago Daily Times, we furnished particulars regarding dredging operations on the Molyneux, in the vicinity of Dunstan Flat. At that time we expressed an opinion that the cnrrent of the river rendered the application of a current wheel, so as to save manual labour, a feasible scheme. A machine constructed upon this principle has, we are pleased to learn, made its appearance on the river at Moa and although the flooded state of the Molyneux for some time past has prevented a fair trial of its capabilities being made, the general outline of the machine favours the opinion that a new phase in the history of Molyneux dredging has been commenced. The machine belongs to the Moa Gold Dredging Company, and the hull was built upwards of three years ago. It was wrought in the first instance with the ordinary spoon elevated by a stern wheel. On this principle a vast saving of manual labour was effected. The dredge, however, happened to be unfortunate as regards the ground selected. At the outset it was wrought in the vicinity of Coal Creek, a few miles above the Teviot. The bed of the river at that place was found to be completely choked up with tailings from back claims in the vicinity, and although one or two very fair patches were struck, the ground turned out upon the whole poor, and the machine was gradually lowered down the river to a point below the Teviot punt, where no better success awaited its labours. Taking advantage of his hard won experience, a number of improvements were suggested by the manager, Mr Ward. These were duly submitted to the shareholders, and after the opposition consequent upon the previous non-success had been combated, instructions were given to have it reconstructed on the principle then proposed. The result has been a machine fitted up with ladder and buckets, in every respect resembling an ordinary harbour dredge, the motive power being applied by two large iron current wheels placed one on each side. These wheels are 15 feet in diameter, fitted with floats, and capable of being wrought up to 10 horse power. The ladder is capable of working 25 buckets, but at present it has merely been fitted up with 13. The buckets can be wrought to a depth of 17 feet; and in a current of three and a half knots an hour will raise half a cubit of wash, emptying it into the cylinder at the rate of from seven to eight bucketsful in the minute. The cylinder is altogether a novel invention. It consists of a round funnel, 2ft Gin in circumference, and 6ft long. It is perforated with upwards of 3000 quarter-inch holes, and when the machine is set in motion it is made to revolve so that, with a plentiful supply of water pumped into it, the sand, and smaller debris are washed through the perforated holes, while the boulders and heavier portion of the refuse are gradually wrought down to the lowsr end of the cylinder. The cylinder itself is set upon a slight incline, so as to facilitate the discbarge of the debris, and projecting as it does over the stern, tailings are thrown off ciear of the dredge altogether. After passing through the cylinder, the smaller particles of stuff are received into two large machine cradles to which action is likewise imparted by the current wheels. Several other improvements for saving the gold have been effected, and, with the view of giving the machine additional buoyancy, two or three additional feet have been added to it; its length now being 14ft of beam.