COX'S SEPARATOR.

By S. H. F. Cox.

This Machine is intended to be used, amongst other purposes, for tin dressing.

It is proposed to take the ore direct from the stamps into a series of conical receivers or hoppers, similar in principle to the model exhibited.

The stamped ore will be carried from the stamps in launders or other suitable channels into the hopper. Water (with a head of at least 12 feet) is admitted at the bottom of the apparatus, and the supply is regulated by the cock through which the water passes, so as to suit all kinds of work. The machines receiving the ore from the stamps will require a stronger flow of water than those treating slimes, where a very gentle flow is all that is needed.

The water, after passing through the cock, is admitted into a perforated tube, through the holes of which the water flows, into the case surrounding the tube, and from thence passes upwards into the hopper, through the annular space formed between the case and the taper plug attached to the screw, which is in the centre of the hopper. This plug is hollow, and has a row of holes around its top edge in such a position that they are always above the annular space above alluded to; and part of the water coming from the case flows through these holes and meets at right angles with the water flowing through the annular space; thus an active agitation of the water at the bottom of the hopper is

produced, washing the ore and separating the mineral from the

waste.

So soon as the hopper is filled by water from below, the stamped ore with its water is admitted into the hopper from above, and the mineral or other ore or materials to be dressed at once sinks towards the bottom of the hopper. It there meets the ascending water coming through the annular space, which ascends with such velocity that only the mineral is of sufficient gravity to sink through this ascending column of water.

The mineral, having passed through the annular space into the case surrounding the perforated tube, is there, by the violent agitation of the water, again thoroughly washed and cleansed from any slime that may still adhere to it; the slime being carried back into the hopper by the ascending current of water. The cleansed mineral then sinks to the bottom of the case, and is carried out through the side cock, by the flow of water there escaping, into a kieve or other receiver.

By means of the hand wheel and screw the taper plug at the bottom of the hopper can be raised or lowered, so as to increase or decrease the area of the annular opening, and thus regulate the velocity of the ascending column of water; and in this manner the machine can be adapted to any class of work, whether coarse or fine.

A series of these machines will, of course, be required to perfect the work, as each one will only deal with one particular size of stuff.

ON ANDRE'S HYDRAULIC MINING PUMP.

BY GEORGE ANDRE, C.E.

The transmission of the force generated by the motor at the surface, whether that motor be a steam-engine or a water-wheel, to the pumps on the several levels in a mine, has ever been a difficulty with mining engineers. The great force requisite to bring up a large volume of water from a depth of many fathoms, and the long distance through which that force has to be transmitted, renders it necessary to employ a connecting medium of great strength, and, consequently, of great weight. That which has been generally adopted consists of a system of wooden rods, and the efforts of engineers have been directed to the improvement of that system, so as to reduce to a minimum the loss of power occasioned by its employment. This minimum has now, probably, been reached; for the system of pump-rods, as at present existing in the county of Cornwall, has attained a degree of perfection beyond which it seems hardly possible to carry it. Yet its most enthusiastic admirers will readily admit that in its most perfect condition it is the source of a great loss of power from friction, especially when the rods are inclined or "flat"; that it offers considerable difficulties to a change of direction, so much so that many changes are impracticable; that it occupies a large portion of the space in a shaft; that its great weight necessitates the use of balance-bobs; that it is expensive, and that it needs a good deal of attention to keep it in perfect working order. These defects are inherent in the system and cannot, therefore, be removed by any improvements that may be devised.

Many attempts have been made to find a satisfactory substitute for this system. That most in favor is to take the engine underground, and either to generate the steam there, or to convey it down from the surface through felted pipes. The condensation, however, which must inevitably take place in the pipes, no matter how perfectly felted, renders the latter method impracticable for great depths. The system of erecting the engine underground is open to many objections; but these are so well known to practical mining engineers, that they need not be fully referred to here. It may not, however, be ill-timed to call attention to what may be considered its two main defects, which are

First: the liability of the pumps to fail by being drowned out, a contingency that would be pretty sure to be realised in the case of a coal mine, by an explosion of gas driving the men out of the workings, or by a great and unexpected influx of water.

Second its applicability to steam power alone.

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The alarming increase in the price of fuel has turned the attention of mining men to the further utilization of water power; and hence the system, whatever it may be, that is to supplant the rods must be, like the rods themselves, as applicable to water as to steam-power.

Such a system the inventor of the Hydraulic Mining Pump now brings forward, in the hope that-when fairly tested-it may prove to be capable of rendering very important service to mining enterprise.

It consists in transmitting the motive force through two columns of water in iron pipes of small diameter.

Of course there is no novelty in the principle of this system. The well-known hydraulic machinery, which we owe chiefly to the inventive genius of Sir W. Armstrong, has shown that water is a very suitable medium for the transmission of power through long distances, and some attempts have been made to apply it to

the working of pumps. But failure has always resulted from the difficulty of keeping the pressure-pipes constantly full, and the pump-pistons in their proper positions. These difficulties have now been overcome. As the columns in the pressure pipes balance each other, the only loss of power in transmission is that due to the friction of the water in the pipes, and this loss will vary according to depth- from 1 to 3 per cent.

Pressure is applied to the columns at surface by means of plungers or rams working in suitable cylinders, which rams may be driven by a beam or a horizontal steam-engine, water-wheel, or other motor. The cylinders in which the rams work are in constant communication with a suitable accumulator, of small dimensions; so that the pressure-pipes are kept full of water and an equal pressure is maintained in both. A small force-pump, worked from the same beam or crank-shaft as the driving-rams, supplies water to the accumulator. A second and an important use of this accumulator is to prevent shock from the change of direction of the stroke when working at a considerable speed, and to signal any displacement of the pump-pistons below, in consequence of leakage or other causes. When such a displacement occurs, a kind of buffer on the piston-rod comes in contact with a standard or stout stud projecting from the bed-plate, and as further motion in that direction is stopped, the motive force is taken by the accumulator, the plunger of which is loaded to a pressure per square inch 'slightly greater than that required to lift the water. The consequent ascent of this plunger indicates that the pump-pistons are not making their full stroke. A ready means is provided for rectifying this at surface. Such a displacement would, however, seem to be impossible, by reason of the pressure pipes being in constant communication with the accumulator, from which any loss by leakage is instantly replaced.

The pressure applied to the columns at surface is transmitted integrally to the pistons of the pumps at the bottom of the mine. These consist of ordinary plunger pumps of simple construction,