under the direction of their fathers or other men, to engage in mining at a comparatively early age.

Table I. shows the gradual increase in the use of ratchet and other hand-machine drills in the Cleveland mines, in percentage of the total output each year.

TABLE I. PERCENTAGE OF THE OUTPUT OF THE CLEVELAND MINES, WROUGHT BY RATCHET AND OTHER HAND-MACHINE DRILLS.

Commenced using ratchet-drills at the Slapewath mines.

+ Introduced at other mines.

Large temporary decrease at one mine, owing to depression in the iron-trade.

FIG. 1.

FIG. 6.-HARDY RATCHET-DRILL.

FIG. 7.-HARDY DOUBLE-HANDLED

RATCHET-DRILL.

Mr. A. L. STEAVENSON (Durham) said that good work appeared to have been done by the drills described by Mr. Charlton, but in his opinion there was nothing equal to an electrically-driven drill, which only required one skilled man to look after it, while unskilled men could do all the other work required in connection with taking down the ore. Electric-drills were also more economical in working than ratchet-drills--good as these latter were. Many of the members had, no doubt, seen electricallydriven drills in operation at the mines in Cleveland under his charge.

Mr. N. R. GRIFFITH (Wrexham) said that it might not be out of place for him to mention that he was driving a drift, in metals, about 2 miles long, and he was using rotary drills worked by compressed air. In hard rocks, percussive drills were used, and in shales and metals, rotary drills were used; and they changed from one system to the other, according to the nature of the strata. If rotary drills would not bore the stone, then they used percussive drills, the drills in all cases being driven by compressed air. A percussive drill did not appear to him to be a very scientific piece of machinery, because, from the nature of its action, it was knocking itself to pieces all the time that it was working. He had not had any experience with electricallydriven rotary drills, and they might possibly have a great future before them.

Mr. W. WALKER (H.M. Inspector of Mines) wrote that he had read Mr. Charlton's paper with much interest, as he well remembered the introduction of rotary drilling-machines, driven by compressed air, into the Cleveland district--at Stanghow ironstonemines about 25 years ago. At that time, it was thought, and especially by the miners, that the circular hole would not produce such good results as the triangular one, but this prejudice was eventually overcome, and at the present time, as the author states, quite one-third of the Cleveland ironstone is got by the power-machines. For some years, even after the introduction of the rotary drilling-machine, the theory that percussive drills were best suited to the mining of Cleveland ironstone was held by many of the mine-managers, and the Eclipse and other percussive machines, driven by compressed air, were introduced into some of the mines. Eventually it was decided to try the

rotary drilling-machine, in the same mine and district as the percussive machine, for a period of three months, and the result proved so conclusively the superiority of the former, both as regards the number of holes drilled and the quantity of ironstone got per shift, that the use of power percussive drills was discontinued, and, at the present time, the whole of the power drilling-machines, whether driven by compressed air or electricity, are rotary machines drilling circular holes.

The methods adopted to dispense with the props, which were at first set between the roof and floor, for the ratchet-machines to be set against, are ingenious and simple, and allow of the shotholes being drilled in the required position and direction; and, at the same time, one man can be drilling holes, while the other is filling away the stone brought down by previous shots.

One point is not mentioned by Mr. Charlton in his paper, and that is that the introduction of rotary drilling-machines was the means of bringing into use compressed powder in the shape used at all the mines in the Cleveland district and also, to a large extent, the use of squibs, both of which have no doubt increased the safety with which shot-firers and miners can do their work. In the old days, when loose powder and home-made straws were used, as they were with the hand jumper-drill, it would have been a physical impossibility for the shot-firers to do as much work as they do now, to say nothing of the increased safety. At first, compressed pellets were introduced, of the shape of the triangular hole produced by the jumper-drill; but it was found that if the shot-hole was the slightest out of truth the pellets stuck, and, in trying to force them in, many miners have been more or less injured. Afterwards spherical pellets were adopted, with such success that they have been used ever since, for both circular and triangular holes, although with a triangular hole great care has to be exercised, as it is very easy for, say, a “flatfronted" hole to become "flat-backed," "flat-topped" or "flatbottomed," or vice versa; and, if this occurs, a ledge or canch is formed, at the spot where the change takes place, in the hole, beyond which it is not possible to pass a compressed pellet without using force which is highly dangerous and a breach of the Coal-mines Regulation Act and the special rules current in the district.