328 THE COLLIERY GUARDIAN. February 15, 1918. MINING INSTITUTE OF SCOTLAND. A general meeting of the Mining Institute of Scot- land was held on Saturday in the Heriot-Watt College, Edinburgh, Mr. D. M. Mowat (Coatbridge), president, in the chair. The President, at the outset, announced the death in action of Second-Lieut. Henry H. Potts. It was agreed to send, on behalf of the institute, a vote of sympathy and condolence to the members of the family. A Fresh Aspect of Intensive Mining. The discussion was resumed on the paper by Mr. George Gibb on “ A Fresh Aspect of Intensive Mining in Thin Seams.” The discussion was closed, and the author thanked. A summary of the observations made by Mr. Richard Kirkby (Wemyss Colliery), Mr. Gibson Reid (engineer to Messrs. J. Nimmo and Com- pany), and the author will be given in our next issue. Capital Charges Considered Along with Current Expenses. Mr. D. M. Mowat (president of the institute) read a paper on “ Capital Charges Considered Along with Current Expenses.” The author said that the title of the paper was an ambitious one, but not more ambi- tious than the subject was important. There was no question that came more often before the colliery manager than that of how to hold the balance between first cost and maintenance charges. Perhaps the most important fact to be kept in view was the purpose of all mining operations. The object of all these opera- tions was not to get coal, iron ore, shale, or fireclay, but gold. If mining operations became and continued to be unprofitable, they must cease. It was often said tb-day—and said truly—that we must aim at greater productivity as an Empire in the future than ever before in the past, to enable the Empire to pay off its indebtedness. This, however, could only continue if the industry as a whole was profitable. It was that aspect of mining, therefore, which must constantly be before the colliery manager whenever he was called upon to decide how much money he could spend on this or that new development of his colliery. For example, a new mineral field is to be developed, and shafts are to be sunk. What size shall they be made, and how shall they be lined and fitted ? This question necessitated taking into consideration the total quan- tity of minerals to be worked from the field, the pro- bable life of the colliery, and the consequent daily output. The necessity for ventilation and the provi- sion of pumps must also be taken into account. But when all these items had been provided for, anything more was extravagance; and if the shafts and fittings much outlived the economic life of the mineral field, they became a monument to their creator’s want of judgment. In the same way, when the seam of coal was reached, and came to be worked, the manager must decide how he would lay off the underground workings in order that the greatest amount of money would be made out of the venture during its lifetime. In making this statement, the author was not advocating parsimonious management. Each problem must be considered by itself, and a decision come to which had regard to all the factors that entered into the case. To illustrate this point, the author mentioned in detail two or three of these numerous problems. For example: What would be the most economic dimen- sions of an ordinary longwall side road? In deter- mining these, one must ask himself what was the purpose of a longwall side road or gateway? It was primarily for the transport of the mineral and perhaps debris from the face of the workings outwards to where it joined the level or heading or slope road from which it was branched. It was also used for ventila- tion, and perhaps for the accommodation of pipes, cables, etc. The brushings or rippings also provided material for the buildings or pack walls. Its life in a machine working might be from four to six months, assuming its length to be 300 ft. What height and width should it be made, so that, taking into consider- ation its first cost, and its cost of maintenance, together with the value of the facilities it afforded for the’various purposes for which it existed, the final result would be the greatest economy? That was a question the author could not answer, but these were the factors which must have consideration. If the road was first made too narrow, and too low, it might not provide sufficient building material, and subsi- dence would be rapid and excessive. Repairs would be required almost from the beginning, and the cost of drawing might be very considerably increased, because the hutches could not be filled properly, and conse- quently a greater number of journeys must be made to strip the wall. On the other hand, the manager might err in the other direction. The road might be made so high and so wide as to require a considerable amount of timber for its support, and its useful life might be completed before its capacity was nearly exhausted. The most economical medium was struck when the oversman could say, when a road was being cut off: “ Well, that’s been a good road, but it is just about time it was cut off.” In the same way, with haulage problems, the question always was: “ What was most economical?” In a good level road a horse would draw six tons of coal per rake and travel 25 rakes per day— a distance of 440 yds. This was 150 tons per day, and was the full output of the section served by this level road. No mechanical haulage would improve upon this, and a foolish manager who introduced it into such a road, because mechanical haulage was the “ correct thing,” had not fully grasped the problem. In examples such as these, it was difficult, if not impossible, to lay down any law for guidance. The object to be attained must always be kept in view, and the whole elements of cost entering into its attain- ment properly accounted for. In the case of provision of pipes and cables sufficient for the purpose for which they were provided, there was ample scope for a more or less exact estimation of the pros and cons, although in any problem it should be possible for an experienced manager to put a value on each of the factors entering into the calculation. The costs of brushing, repairing, in diameter The over-all dimensions are: Length over buffers, 19 ft. 8 in. ; width, 8 ft. 4 J in.; and height to top of cab, 9 ft. 3f in. The total weight is 17 tons. The under-frame is built up of channel iron. The elec- trical equipment, supplied by the D. P. Battery Com- pany Limited, of Bakewell, consists of two motors, one per axle, of the British Thomson-Houston Com- pany’s G. E. pattern. These are two-turn, series wound, up to 250 volts, each rated at 27 b.h.p. on 160 volts, 36 b.h.p. on 216 volts, and 41 b.h.p. on 250 volts, this rating being for one hour, with a temperature rise not exceeding 75 degs. Cent. The spur and gear wheels have a ratio of 4 to 6. The motors are suspended, on the outsides of the locomotive axles, from channel iron girders across the under-frame, with brass bush bear- ings on the axles, whilst the spur wheels work into gear wheels, which are keyed on to the axles. The motors are capable of hauling 90 tons behind, at 10 miles per hour on the level, or 72 tons at 11 miles per hour, in addition to the weight of the locomotive. They are controlled from the cab by a tramway-type series parallel controller through two grid resistances fixed under the floor. The controller has a separate forward and reverse handle, in addition to the control handle; also a switch to cut out either of the motors in case of failure of the one. Separate magnetic blow-outs are provided for each contact. An automatic circuit breaker and a double-pole change-over charge and dis- charge switch are also fixed in the cab within reach of the driver. There are also 0-300 range voltmeter and a 100-0-300 range ammeter fixed within his view, and six small circuit switches for the lighting circuits. These consist of cab light, portable light, and four head lights, which are fixed in bulkhead fittings over each buffer. The coupler socket for charging is mounted on the outside, under the top step, and the main fuse box outside on the under-frame. The battery consists of 108 21-plate cells of the D. P. Company’s train light- ing type. The positive plates are of the Plante type, f in. in thickness, whilst the negative plates are of the “ sponge ” or “ box ” pattern. The boxes are of teak, with lead linings, and are fitted with split block type lids, rubber gaskets, vent plugs, and acid level floats. The plates, resting on the D. P. Company’s special four-bar bottom blocks, are 2 in. above the bottom of the cell box. The separation between the plates is made of treated ribbed wood sheets. Each section has double plugs, and is connected to flexible copper con- nectors, with lead plugs and lead-coated bolts. They are fixed in the compartments on either side of the timbering, and drawing were all items of which reason- able estimates could be made. The author said, in conclusion, that he had only touched the outer fringe of the subject, but he hoped he had said sufficient to encourage the members to state their views, illustrated with examples from their own experience, because it was from such a free interchange of views that one’s knowledge was most profitably extended. The discussion was adjourned to a future meeting. Stripping and Re-Lining a Shaft at Cowdenbeath, Fife. Mr. Henry Rowan (Cowdenbeath, Fife) read a paper on “ Stripping and Re-Lining a Shaft at Cowdenbeath, Fife” (see page 331), the discussion of which was adjourned. The Occurrence of Coking Coal in Scotland. Mr. Robert W. Dron (Glasgow) afterwards read a paper on “The Occurrence of Coking Coal in Scot- land ” (see page 326), which was held over for dis- cussion at next meeting. ELECTRIC BATTERY LOCOMOTIVE FOR STAFFORDSHIRE COPPER WORKS. By F. C. Coleman. The locomotive works of the North Staffordshire Railway Company at Stoke-on-Trent have recently built an electric battery locomotive, which is being used for shunting purposes at the Oakamoor Copper Works of Messrs. Thomas Bolton and Sons Limited. The body and cab are constructed of wood, braced with iron, whilst the covers over the battery compartments are arranged to drain off all rain water, and the sec- tions are so arranged that efficient ventilation is obtained, and the gases given off during charging or working the battery are carried away. The locomotive has a wheelbase of 8 ft., and the wheels are 3 ft. 1 in. driver’s cab, each on four porcelain double insulators, the bottom halves of which are sunk in wood strips secured to the floor. The cells are divided from each other by special wood corner separators, which leave an air space of f in. around each cell. The following table gives the capacity of the battery: — 30 amperes for 10 hours to 1’8 volts per cell. 50 „ „ 5 „ „ 1'8 „ 71 » „ 3 „ „ 1’8 ,, ,, 150 „ „ 1 „ „ 1'75 „ 300 „ ,, 1 minute. 375 „ „ 3 seconds. The charging rate is 30 to 60 amperes. The weight of one cell, complete with acid, is 132 lb., and the total weight of the battery is 6 tons 8 cwt. Shunting and warning signals are given by a 12-volt “Klaxon” horn, connected to six of the accumulators, and actuated by a hand push within easy reach of the driver. The locomotive was built at the Stoke-on- Trent works, and to the joint specifications and designs of Messrs. J. A. Hookham, the company’s locomotive engineer, and A. F. Rock, the electrical engineer of the North Staffordshire Railway Company. OFFICIAL VISITS TO COAL FIELDS. Sir Albert Stanley, M.P., the President of the Board of Trade, and Mr. Guy Calthrop, the Coal Controller, with Sir Richard Redmayne, the Technical Adviser of the Coal Controller, and other Government officials, are making a tour of coal fields, for the purpose of studying colliery arrangements and the conditions of mining areas generally. They visited South Wales, and descended the Maritime Colliery, near Pontypridd. On Tuesday they commenced their Lancashire tour by visiting Wigan, and inspected plant at the Atherton collieries of Messrs. Fletcher, Burrows and Company. Electric Battery Locomotive, North Stafford Railway. -rU IJ Worth e. ■ A.'’’■Z’X' w They noted the dining arrangements, miners’ baths, rescue provision, etc., after which the party proceeded to the mines of the Wigan Coal and Iron Company at Clock Face, St. Helens. There the model mining vil- lage was inspected. The tour included the Yorkshire coal fields on Wednesday, and the Lanarkshire mining area on Thursday. The housing conditions received special attention. Coal Conciliation Board. — The miners’ representatives informed the Coal Conciliation Board for the Federated districts that three months’ notice to terminate the pre- sent agreement will be given on April 30, in order to open negotiations for a new agreement. They desire an increased minimum (including the present bonus), while excluding any fixed maximum. The Board discussed the Whitley Report. It was stated that the Lancashire and Cheshire Coal Association and the Miners’ Federation of the two counties had already recommended the establish- ment of local joint pit committees, and similar action in other mining districts was recommended. Gas Making and Residuals.—-Speaking at the annual meeting of the South Metropolitan Gas Company, Dr. C. Carpenter (chairman) said that although the company paid an increase of over £200,000 for coal in the past six months, the return from residuals was less, owing to restrictions on the exporting of sulphate of ammonia. The price of sulphate had averaged under £15 per ton, compared with £18 or £19 before the prohibition on export. The com- pany carried only about 32 per cent, of the coal in their own vessels, and for the rest paid from five to seven times the freightage of pre-war days. The directors hoped to obtain some relief by promoting a Bill. High-Speed Tool Steel.—The Minister of Munitions has modified the Order regarding high-speed tool steel. Under the heading “ Maximum basis prices for high-speed tool steel,” the words “ finished bars, 14 per cent, tungsten or its equivalent, 3s. 8d. per lb., delivered buyers’ works; finished bars, 18 per cent, tungsten or its' equivalent, 4s. 5d., delivered buyers’ works,” are substituted for the words “ finished bars, 14 per cent, tungsten, 2s. 10d., delivered buyers’ works; finished bars, 18 per cent, tungsten, 3s. 10d., delivered buyers’ works.” Under the heading “ High-speed tool steel extras,” the words “ pack- ing, 4s. per cwt.” are inserted. Under the heading “ Scrap from high-speed tool steel,” the words “ millings and turn- ings, 8d. per lb. net., delivered steel makers’ works; bar ends, 9d. per lb. net, delivered steel makers’ works,” are substituted for the words “ millings and turnings, 5d. per lb. net, delivered steel makers’ works; bar ends, 6d. per lb. net, delivered steel makers’ works.”