October 27, 1916. THE COLLIERY GUARDIAN. 801 industries, and also a number of young persons under 16 years of age. The shortage, however, has not been fully made up; the total number of persons employed below and above ground during 1915 was 109,528, or 10,110 less than in the preceding year. The decrease in males above 16 employed underground wTas 9,501, while the decrease in males above 16 employed above ground was 2,177. The number of young persons under 16 employed underground was 1,120, and above ground 433 greater than in the preceding year. Notwithstanding the decrease in the ' number of persons employed underground, the output of coal was 27,587,042 tons, or 156,050 tons greater than in the preceding year, while those of fireclay and of ironstone show decreases of 93,842 and 163,704 tons respectively. The total output of all minerals was 28,918,382 tons, which shows a decrease of 99,725 tons. The increase in the coal output is doubtless due to the employment of men from mines producing other minerals, and also, to some extent, to work in the less productive seams and sections of the mines having been temporarily suspended. The number of accidents increased. There have been no important developments with regard to ventila- tion, suppression of coal dust, support of roof and sides, rescue work, or treatment of animals. Work at the rescue stations has been somewhat disorganised owung chiefly to the large number of trained men who have 'A 15 HI I LENGTH ©VER BUMPERS, 1 o'-s" LENGTH INSIDE BODY, 9'-o" Fig. 1.—Side Elevation of Car. joined H.M. Forces, thus necessitating re-organisation of the teams to which they belonged. Accidents. The total number of fatal accidents was 139, causing 187 deaths, as compared with 123, causing 125 deaths, in the preceding year. The death rates from accidents per 1,000 persons employed were : Above ground, 0-760; below ground, 1-987; above and below ground, 1’707; as compared with 0-150, 1-302, and 1'045 respectively in the preceding year. Two fatal accidents from elec- tricity were reported, one underground and one above ground, each causing one death. Dangerous Occurrences.—During the year 139 dan- gerous occurrences were reported. Of these seven were ignitions of firedamp by naked lights; one was an above ground fire; 99 were underground fires; two were breakages of winding machinery; 15 were breakages or failures of winding ropes or their connections; seven were overwindings; two were inrushes of water; one was a burst pipe in a rising water main; and one was the ignition of a lucifer match struck and ignited by a fireman’s shovel when cleaning a haulage road in a deep, dusty, and fiery mine. Of the 99 underground fires, 96 were due to spontaneous combustion, and 76 of these occurred in the Thick coal. Prosecutions. Proceedings against the owners and managers were instituted in two cases. Of the 145 prosecutions by owners against employees for contraventions of the Coal Mines Act, 1911, and the General Regulations, and of the Cruelty to Animals Acts, 102 convictions were obtained, and three were withdrawn on payment of costs. Company Re-arrangements in South Wales.—There have been active dealings in the shares of the Rhymney Iron Com- pany and of the Powell Duffryn Colliery Company at Cardiff recently, and rumours were rife on the Cardiff Exchange of the impending merging of the Rhymney Company with a large colliery concern, either the Powell Duffryn o-r the Cambrian Combine.—The W. and C. T. Jones Steamship Company Limited, Cardiff, has made a valuable addition to its fleet by the acquisition of three steamers belonging to the Orpheus Shipping Company, of Sunderland, of which the managing owners are Messrs. Jenneson Taylor and Com- pany, for whom the Cardiff agents were Sir R. Ropner and Company Limited. This purchase involves a sum probably of about <£250,000 to £300,000. North-East Coast Institution of Engineers and Ship- builders.—The 33rd annual meeting commenced yesterday (Thursday). The agenda included a paper on “ Works Organisation,” by Messrs. A. D. C. Parsons, E. L. Orde, and G. H. Tweddell. The proceedings will conclude this evening (Friday). The 1916 institution scholarship (value £50 per annum) has been awarded to E. V. Teller, an apprentice in the service of Messrs. Wm. Gray and Company Limited, West Hartlepool. The council, believing that the time has arrived for making the subjects of the institution’s scholarship examination more comprehensive than hitherto, have decided that the syllabus of future examinations shall be : English: English history and geography; Latin, Greek, French, or German (one of these four); extra mathematics; either experimental science and mechanics, or any two of the following : chemistry, physics, mechanics. MINE CAR DESIGN* By Marcus L. Hyde. Restrictions, imposed by both legislation and labour, have so hedged in the mimng industry that but little opportunity exists for further reducing costs. Haulage is probably the most vulnerable point open to attack, and the mine car, the chief item in this department, deserves particular attention. Manufacturers claim a standard car is not feasible, and operators have in most instances been strongly influenced by their choice by the experience of immediate neighbours. Under these conditions it is no wonder cars are excessively high, both in first and main- tenance costs. In the writer’s belief mine cars can be standardised for most mines where motors are practi- cable. Two gauges, 32 in. and 42 in., should cover all requirements, and it will be found that the range in shape and size to meet different local features will not be such a formidable one. Both the manufacturer and operator would be benefited were cars standard; the former by the increase in sales of a better product, the latter by the lower costs, longer life, higher salvage value, and ease in obtaining repairs. Car Design in Detail. In working towards a standard design strength and simplicity are paramount, and great care must be exer- cised that the introduction of refinements is not over- done. The ratio of dead to live load must be a minimum. Over-all dimensions of the car body should not exceed lift, in length, 6ft. in width, and 3| ft. in height above the rail. The limit in capacity should be 4 .tons. Motors gather and deliver a large car to the tipple in the same time taken for a small one. Increas- ing the car capacity therefore increases the tonnage per trip, the capacity of storage tracks, and the capacity of locomotives. The draw-bar pull does not increase in ratio with the capacity; hence the power required to Fig. 2.—Ground Plan of Car. -Q. . © p J ;,£■ move the cars is proportionately reduced. In motor gathering the earnings of a loader depend on the schedule of the motor; he naturally, therefore, prefers the large car when paid on a tonnage basis. The success of the mechanical loader of the future will rest on this principle. It is obvious that the capacity should approach as near the lifting 4 tons as the conditions will permit. Alines paying on a screened coal basis unfor- tunately are restricted in the size of car they adopt’ to two tons; the 6 by 12ft. bar screen being unable to handle a greater mass at one time. Before going into details, let us study the shocks a ear must resist. Of all these, the dumping strains imposed by a horn dump are worst. The car is suddenly- stopped by its front wheels, thrown to an angle of 50 degs., then dropped back. The wrack on truck, truck- bolts, and entire body is tremendous. Truck bolts are loosened, play accumulates between trucks and bottom, the bottom shakes loose from sides, and a ruined car is the eventual result. In starting, a heavy car is wracked from end to end, especially if waste play be permitted in coupling links. In stopping suddenly, cars bump together, and there is a severe tendency to buckle the bottom; the load keeps moving, which results in both the body and the end gate being wracked—particularly the latter when not rigidly fastened. In going around a curve there is an inward thrust against the wheel flange * Canadian Mining Institute Bulletin. which must be taken up, and the life of a car depends to a great extent on how this is done. ' The shocks above described may best be cared for in the following manner : Dumping strains—by abandon- ing the horn dump or permitting only the spring type. Starting shocks—by equipping cars with spring draw- bars. Stopping and bumping shocks—by a strong oak bottom. Inward thrust of curved rail on flanges—by use of a properly designed wheel. Where the wheel flange strikes a curve, the wheel is canted over; the resulting strains should as far as possible be absorbed in the truck itself, not transferred to the car bottom. Again, the wheel hub should not be permitted to first strike the end of the journal. The Whitney truck is a very popular type in the United States. Under curve conditions the inside of the wheel cap of this truck comes in contact* with the end of the axle—where both wear and friction is a minimum—pushing it through both journals until its collar strikes the journal on the far side. The frictional resistance of sliding caused by the weight of the car absorbs this impact, which would otherwise travel from the wheel hub through the journal, direct to the car bottom. If the hub is per- mitted to transfer this strain in full to the journal, the wear on both soon becomes serious, side play accumu- lates journals, funnel, and wheels wobble. Car Boxes (Figs. 1, 2, 3, 4). Wooden boxes depend for their stiffness on tough wood, binder irons, and bolts. As soon as a car is put in the mine, the wood starts shrinking, rotting, and wearing away from abrasion; bolts work loose, lost motion permits journals to play, and cars to jump the track. After one or two such accidents, the bottom sags, bumpers ride, and re-building becomes necessary. Paint neither preserves nor protects; abrasion cuts it away as fast as applied. Sheet steel boxes on oak bottoms have so far proved superior to any other combination. The sides should be made up of three separate sheets, so fastened that they may be easily and quickly removed, and straightened in case of damage. Bottom side plates should be of in. steel, and flanged. These act as beams to support the wooden bottom, and prevent it from sagging. The side plate flanges on the car bottom serve as axle straps to hold the axles parallel and rigid, thus maintaining the efficiency of the journals, and avoiding the running strains on the body. They further facilitate a free flow of coal along the bottom. By making these plates stiff, the necessity of binder irons, other than one at the centre and ends, is done away with. Flare plates should be of in. steel, should barely clear the wheel flange, and should lay on an angle of 16 to 17 degs. The top plates should be of ~ in. steel, rolled on top for stiffness, and to give a smooth edge for holding on to. The back plate should be of in. steel, rolled on top for stiffness, and reinforced on outside with two vertical angles. Riveted stiffeners, fillers, angles, etc., are objectionable; and a flanged connection is preferable in every case. Binder irons at the front of the gate type car should be tied across the car top by a 2 in. pipe spanner. This acts as a strut in case of a side blow7, thus causing both sides to resist the strain, instead of one. Boxes should not permit of leakage, should offer no resistance to flow of coal, or encourage damp slack to cake; they should be free also of all outside projections that could possibly scratch or catch a passer-by. All bolts should have grip nuts. Each body should be numbered in large w’hite figures. A substantial check hook is •needed that will permit of a check being hung on the outside of the gate, and yet prohibit its removal by any other than the authorised person. The solid box car is preferable wherever its use is practicable. Initial and upkeep costs are less; the life is longer; the car is not so subject to distortion from strains imposed by a tendency of the load to continue its forward travel after a sudden stop, there is no leakage, and the capacity is greater for a given width. The rotary dump is easier on both car and coal: so much is this the case, except in shaft mines, that the instal- lation of horn dumps is inexcusable. In shaft mines the advantage of self-dumping cages is conceded by most authorities, and these require a car with an end gate. A lift gate is quicker and safer than the hinged gate held bty latches that must be shut by either trip maker or loader. Afany serious wrecks have been caused by gates not being properly latched, and by coupling pins not being forced home. A good lift gate must be rigid, as near non-leakable as possible; certain to re-seat after dumping; and, w’here used on an incline