18 THE COLLIERY GUARDIAN. July 3, 1914. steel extension. The indicator is of the vertical pillar type, the vertical screw spindle being driven through machine cut bevel wheels at the bottom of the pillar from the drumshaft, and has the requisite nut and pointer with adjustable overwinding stops to engage levers con- nected to the emergency trip gear. A bell is fixed to the pillar and is rung by the pointer in passing. The drum shaft bearings are fitted with Stauffer lubricators. The particulars of this electric winding engine are given in the following summarised schedule :— Depth of shaft—about 241 ft. Material—coal and stone. Net weight out of balance—17 cwt. Maximum weight out of balance—22 cwt. at week ends. Weight raised per hour—127J tons. Banking period—10 secs. Speed limit winding for men (average)—10 ft.per sec. Circumference of rope—34 in. Weight of cage and suspension gear—27 cwt. Weight of empty tub—5 cwt. Weight of coal in tub—8| cwt. Tubs per cage—2. Number of tubs—1. Type of drum—Plain cylindrical. 120 600 IOO 500 250 80 400 200 60 300 200 >00 20 iOO SO 0 90 ___„tBCS Fig. 4—Recording Charts giving Characteristics of Equipment. Volts Kilowatts Fig. 5.—Winding Plant, Bowdon Close Colliery—Sectional View. / I; ' L l r i Fig. 6.—Winding Plant, Bowdon Close Colliery—Plan. The supply is three-phase 40 cycles, the voltage being transformed down to 220. Views taken from three different positions in the winding house are given in figs. 1, 2, and 3. Whilst these illustrations are self explana- tory, and require little further in the way of description, it may be said of the view showing the control platform ,—that it is Messrs. Crompton and Company’s practice to supply an apparatus with which the average engine driver is familiar, and to avoid fixing anything electrical on the control platform itself. It will be noticed that the control levers, which are of the steam engine pat- tern, are three in number, those operating the controller and reversing switch being mounted together and mechanically interlocked in such a manner that it is impossible for the driver to operate them in their wrong order. The single lever is for emergency use only, and trips the main brake weights. The motion to the switchgear is transmitted through levers and way shafts passing under the control platform. There is also a mechanical connection between the emergency hand lever and the depth indicator which comes into opera- tion in the event of an overwind occurring. As a further precaution against overwinding the controller lever is mechanically connected to the depth indicator so that it is automatically pushed over to the “off” position as the cage reaches the surface. With regard to the electrical equipment, this com- prises a rotary converter, main motor, transformer, and the necessary control switchgear. The rotary converter is fixed in a separate room adjacent to the winder house. The current from the secondary of the transformer is led to the slip-rings of the rotary. The rotary converter field winding is permanently connected to its commu- tator, and, being fitted with amortisseurs, pulls into synchronism without the use of any synchronising apparatus whatever. It is, therefore, not necessary to provide skilled electricians for starting and stopping, which operation can be performed easily by the engine- men. Coupled direct to this rotary and mounted on the same bedplate is a variable voltage generator, having special windings for limiting the maximum demands from the mains which incidentally prevents the equip- ment being overloaded through careless or indiscreet handling of the controller. The armature of the gener- ator is connected in series with the rotary armature, the fields being excited so that the voltages oppose or assist each other according to the position of the controller. The series or limit winding of the variable voltage gener- ator is wound so as to oppose the shunt field, the resul- tant field bearing a relation to the current supplied to the main winding motor which is thereby limited. The motor speed is entirely controlled by varying the applied voltage, and as there are no series resistances the motor may be run for long periods at a crawling speed. As will be observed from the chart, fig. 4, the equipment is working to a very fast schedule, and in order to obtain rapid acceleration the motor is provided with special windings. The chart gives the characteristics of the equipment; these curves are reproduced from actual charts taken from recording instruments on test, the curves shown in chain line representing the kilowatt demand, which is computed from the current and voltage curves and the known efficiency of the plant. Atten- tion may be called to the shape of the kilowatt curve, which is less during the accelerating period than at full speed, these results being the reverse to those obtained with other methods of,control. With regard to the cur- rent consumption, this was guaranteed not to exceed 0-5 units per ton, and on the official tests which were taken by a disinterested party, we understand the actual con- sumption was found to be 0-45 units per ton. MINING INSTITUTE OF SCOTLAND. Annual Joint Excursion. The second annual excursion under the joint auspices of the Mining Institute of Scotland and the Scottish branches of the National Association of Colliery Managers and the Association of Mining Electrical Engineers was held on Saturday last under favourable weather conditions. The company, which was a repre- sentative one, drawn from all parts of Scotland, gathered at St. Enoch Station, Glasgow, and were conveyed from there to Greenock per special train. At Greenock the magnificently appointed steamer “ Neptune,” which had been specially chartered for the occasion, was in readi- ness to take the party, which numbered quite 250, on a cruise up Loch Fyne. Amongst those present were :— Mr. Jas. Hamilton, president of the Mining Institute of Scotland; Mr. Alex. Anderson, Wishaw, president of the Association of Mining Electrical Engineers; Mr. Richard McPhee, Bothwell, president of the Scottish branch, N.A.C.M.; Mr. Matthew Brown, president of the West of Scotland branch, A.M.E.E.; Mr. A. B. Muirhead, president-elect of the West of Scotland branch, A.M.E.E.; Mr. N. A. Wilkie, Cardenden, president-elect of the East of Scotland branch, A.M.E.E.; Messrs. D. M. Mowat (Summerlee Coal Company); Jas. Bain (Alloa Coal Campany); Jas. Barrowman, mineral factor on the Hamilton Estates; Sam Mavor (Messrs. Mavor and Coulson, Glasgow); Harry Lewin, mining engineer, Glasgow; D. G. McLauchlan, mining engineer, Edinburgh; George A. Bishop (Cadzow Coal Company); D. A. Warren and Norman Hunter (Messrs. Hunter and Warren, Glas- gow); J. Balfour Sneddon, Mid Calder; Douglas Jackson, Coltness; Robert Ramsay, Niddrie Collieries; Jas. Allardice, Coalburn; Wm. Williamson, Hamilton; Henry Rowan (Fife Coal Company); John Paul, Loch- gelly; W. H. Telfer (Wilsons and Clyde Coal Company); R. W. Dron, Glasgow; Wm. Jarvie (Messrs. Wm. Baird and Company); James Gibb, colliery owner, South Wales; Edward Parker, secretary of the Institution of Engineers and Shipbuilders in Scotland; David Beveridge, Kelty; Wilson, Giffnock; John Clark, Glen- craig, Fife; Donald Black, Bathgate; Wilson, Alloa; Boyes, Wishaw; H. A. McGuffie, Glasgow; Frank Anslow, Glasgow; S. A. Simon, B.A., Glasgow; Robt. Scott, Kirkconnel; J. B. Thomson, Hamilton; Wm. Kilpatrick, Larkhall; James Gillespie, Glasgow (Messrs. Siemens Brothers); C. E. Hart, Glasgow; A. Robinson (Messrs. Keith and Blackman), etc. Capital arrange- ments for the outing, which in every way was a con- spicuous success, were made by the joint secretaries, Messrs. G. L. Kerr, Glasgow; James Kirkpatrick, Both- well; David Martin, Glasgow; and R. W. Peters, Loch- geUy. Output of Pennsylvania Anthracite. — According to the figures reported to the Topographic and Geologic Survey of Pennsylvania, working in co-operation with the United States Geological Survey, the production of anthracite coal in 1913 was 6,395,825 gross tons in excess of the output of 1912, an increase of 8| per cent. Part of this increase is due to the closing of the mines in 1912 pending the settlement of the mining scale, yet it is almost 1,000,000 gross tons in excess of the production of 1911, which was the previous high record year. There was an increase in the total selling price at the mines in 1913 of $17,558,501, as compared with the pre- ceding year, the average price per gross ton being $2’38. as compared with $2'36 for 1912. The average cost of mining anthracite coal in 1909, as reported by the Census Bureau, was $1’93 per ton, exclusive of any charges for depreciation, amortisation, or interest. On the same basis, with the increase in the mining rate as provided in the agreement of May 20, 1912, the cost would be, according to Mr. E. W. Parker, of the United States Geological Survey, $2’07 per ton. This would mean in 1913 that the average selling price was 31 cents per gross ton above the mining rate, from which must be deducted the items of depreciation, amortisa- tion, interest, and the increase in all items of expense not covered by the agreement of May 20, 1912.