386 THE COLLIERY GUARDIAN. February 19, 1915. provided in the indicator case. This solenoid releases a pawl. Thus on the winding engine being started, the indicator is cleared of its signals, and the pointer and flag return to zero. As the. contact-making release will work with the starting or stopping of the winding engine, it is of service in signalling during shaft repairs. Casf-flluminium Ratchet for !2 Signals Adjustable Standard to suit famous Sijes of Gongs Fig. 5.—Method of Resetting the Indicators by Mechanical Means. RA SE STOP II !0X 9X Adjustable 'lop for Plunger WE RA St fl ' Engineman's Release 8 = CranK which operates Lerer C mth Adjustment O - Release Leeer £ - Disc on Depth -Indicator Shaft for Automatic Release Fig. 7.—Mechanical Indicator before “Men” has been Signalled. lower STEADILY 'STEADILY. X 4 Banhaman QflStfTfr. Converting \Mer L----4jifop, .'/Plorfei ’'\iead-. \/v/' Zero , natsr Mechanical" Signals into Electrical Signals. Fig. 6.—Another Method of Resetting the Indicator from a Depth-indicator by Mechanical Means. Fig. 9.—Contrivance for When the engine, stops, the balls gravitate in the race and again clear the signal, so that it is impossible to accumulate and register incorrect signals. Where the cages have two or more decks, the oontact- making release is then so arranged that the flag remains visible during . the decking of “ men,” while the executive, signal is released at each change of deck. The two arms of the ball races previously mentioned are separately adjustable in regard to their angles of inclination, consequently it is easy to arrange matters so that the signals may be cleared at any desired point in the winding by making the incline up which the con- tacting balls travel more or less steep : one may be connected to clear the cautionary signals, and the other to clear the executive signal, or both may clear the signals simultaneously. The conitact-making release, although primarily devised for installation with the visual signals described, is a self-contained and independent unit of mechanism, and may be adapted to any and every electric system of signalling indicators. If it should, however, be desired to reset the indicators other than by the ball race, it may be accomplished in the following manner :—A ratchet may be provided in the indicator to release the pawl, and a mechanical flexible wire carried through the indicator case to a foot- trigger, to be controlled by the engineman. Such an arrangement is shown in fig. 5. The mechanical wire may also be automatically controlled by the depth indicator through cranks, as shown in fig. 6, a system which is already in successful operation. Mechanical Signals. It will be seen by reference to figs. 7 and 8 that the appearance of the mechanical bell and indicator is very similar to the electrical apparatus; indeed, the con- struction differs but slightly. The mechanical apparatus has a dial, on which is inscribed the nature of the signal. A hand travels step by step over the dial, and a flag appears in a space of the dial showing the cautionary word “ men.” Two plungers strike a bell in common, as in the electrical apparatus, but instead of the solenoid actuating the plungers, mechanical levers compress springs which eventually release catches that liberate the plungers. These plungers are provided with pawls, which actuate the mechanism as previously described. In order to reset the indicator, a release pawl is provided in the case, and this can be operated as previously described, and as illustrated by fig. 6. It will' be seen that in order to operate the non- cumulative indicator, two mechanical wires are needed, one to give the cautionary and one to give the executive signal. Mechanical Signals to the Pit Bank and Therefrom Converted into Electrical. Where mechanical wires are already installed in the shaft, and it is preferred to retain them, but where a difficulty is experienced in carrying .a mechanical system throughout, it is quite practicable to convert mechanical into electrical energy tai any desired point. There are many such eases in operation where at the pit bank the pull of the mechanical wires actuates an electrical contact maker. Fig. 9 shows such a contrivance, as the system then becomes electrical from this point. The apparatus requited therefrom is as previously explained. : ‘ The various systems described by the' Writer are at work at collieries, and have not only the approval of the Home Office, but appear to have met with appre- ciation in actual practice. Colliery companies are now so well equipped with efficient electrical engineers that the writer feels that it would be a work of supererogation to indicate the best method of installing apparatus, or to define further the Home Office Order and code of signals. MINING INSTITUTE OF SCOTLAND. A general meeting of the Mining Institute of Scot- land was held in the Heriot-Watt College, Edinburgh, on Saturday afternoon last. Mr. James Hamilton, Glasgow, the president of the institute, occupied the chair, and there was a large attendance of members. The following were admitted to the membership of the institute :•—Messrs. Alexander F. Campbell, colliery agent, Stirling; Thomas Chambers, colliery manager, Dalmellington; Hugh M. Clark, mining engineer, Glasgow; and James Wilson, B.Sc., colliery manager, Bengal, India; while Messrs. M. B. Craig, Kilmarnock; and Jarnos Edward, Shawlands, Glasgow, were added to the roll of federated students. Roll of Honour. It was announced that the council were desirous of making out a roll of honour, in connection with the Institution of Mining Engineers, of members of the Mining Institute of Scotland who had joined the Navy RAISE -HOWER STEADILY J RAISE STOP Z 4 5/ Fig. 8—Mechanical Signal after “ Men ” has been Signalled. or Army for service at home or abroad in the present European War. The President said it was his duty to ask the members of the institute to honour the memory of one of their number, Lieut. Andrew Burt, of the 8th Royal Scots, who had fallen in action at the front. Lieut. Burt, who was a colliery manager at Tranent in the East of Scotland, had many ties which -would, if he had so chosen, justified him in not ‘responding to the call of the country at this time. Instead of that, however, he had gone out with his regiment to France, and the result they all deplored. He proposed that they should record in the minutes their appreciation of the patriotism of their late colleague, and that an excerpt of the minute be forwarded to the bereaved relatives. The motion was unanimously adopted. Fan Testing, and the Measurement of Pressure. The discussion was thereafter resumed on the paper previously contributed by Mr. Thomas Bryson, Glasgow, on “ Fan Testing, with Special Reference to Measure- ment of Pressure.” Mr. John B. Thomson, Hamilton, remarked that, from the title of the paper, and the observations made at the outset, one would assume that the water , gauge the author was discussing was the water gauge to be ascertained for the purpose of determining the efficiency of a fan. If that was the ease, he thought Mr. Bryson’s remarks on conservation of energy in relation to the measurements of pressurej and his reference to the Bernouilli theorem, were absolutely, irrelevant. So far as the experiments were concerned-, he thought'.it, was quite evident, from the supplementary remarks made by the author, that the Pitot tube method was the more accurate. He had no doubt if a committee was appointed to investigate the matter, their experiments