September 20, 1918. THE COLLIERY GUARDIAN. 601 general immunity from this risk at those stations sup- plied with electrolytic oxygen. Oxygen containing more than one-half of one per cent, of hydrogen ought never to be used for rescue apparatus. It is especially important that the superin- tendents of those stations supplied with electrolytic oxygen should analyse all oxygen received. It is not sufficient to accept a works guarantee. Unless the oxygen percentage exceeds 99|, the hydrogen propor- tion should also be ascertained. The results should be recorded in a book kept at the station for that purpose. The Influence of Cold on the Absorption of Carbon Dioxide.—Experience of the use of Proto apparatus in wintry weather and experiments in the laboratory have made it clear that caustic soda, when cold, is only a tardy absorber of CO2. In British mines, it is true, the temperatures are usually such as make this fact of small practical consequence; yet in colder countries, or in military or fire brigade operations, it may be necessary on occasion to guard against the effect of low temperature. To warm up the caustic, the wearer should, in such circumstances, inhale from fresh ail’ and exhale through the apparatus for a few minutes before finally clearing out the apparatus with oxygen and starting to use it. The influence of cold on the rate at which CO2 is absorbed deserves the closest attention on the part of de- signers of liquid air apparatus- Liquid Air Rescue Apparatus.— In a later report it is proposed to deal at length with liquid air breathing apparatus. The present, however, is a fitting time to notice the great strides that have been made in this form of apparatus, chiefly through the labours of Colonel Blackett, Mr. F. P. Mills (Newcastle Station) and Mr. E. Elliston (Rotherham Station). The apparatus now in use at Rotherham and the stations of Northumberland and Durham can indeed claim to be a safe and suitable type for mine rescue purposes. Testing Breathing Apparatus. Systematically and frequently to test apparatus is one of the best of safeguards. A thorough test should be made of every breathing apparatus at a rescue station or mine at least once a month. It is useful to keep a record of the tests, the apparatus being numbered to facilitate reference. The dates of replacements and repairs can then be traced, and special tendencies of any apparatus—for though they may be outwardly alike some give more trouble than others—can be kept continuously under observation. In examining an apparatus the first thing done is to turn on the oxygen and read the pressure gauge. Several instances liave been brought to notice of the unreliability of the small gauges attached to appara- tus. Obviously a faulty gauge not only vitiates this test, but also forms- a serious source of danger- during active work. Especially is this the case when the lower readings are in error or when there is sluggishness of movement at the low pressures. An inexpensive and simple arrangement designed by Dr. Briggs is illustrated below. It allows of Appliance for Testing Pressure Gauges. k SECTION ON XX gauges (g, g) being compared, six (or less) at a time, against a standard gauge G, calibrated at the National Physical Laboratory, Teddington, to which place it should be returned for examination once a year. A small oxygen cylinder C, charged to 120-150 atmo- spheres, is attached to the appliance and the oxygen turned on. After the gauge readings have been taken, some of the gas is exhausted by means of the tap T, when the gauges are again compared. In this way any number of readings is obtainable between the initial pressure and zero. More elaborate apparatus for testing pressure gauges are described in Messrs. Schaffer and Budenberg’s catalogues. Their only objection is that of price. Leakage Tests.—By far the best test is to immerse the whole apparatus in water with the oxygen turned on and with the mouthpiece closed by the thumb. As the bags become distended bubbles rise from faulty joints on the circuit, while leakage of high pressure oxygen becomes evident at once. No apparatus should ever be used in poisonous air until it has passed this test. Oxygen Delivery Tests.—All instructors are familiar with the drum wet meter. Provided this meter is filled with water to the correct level, and that it is not used for measuring currents beyond the capacity intended by the maker, it proves an accurate means of measure- ment. A simple form of gauge for measuring oxygen delivery on a principle suggested by Dr. Haldane has been put on the market by Messrs. Siebe, Gorman and Company. Draeger’s float litre meter consists of an upright glass tube protected by being placed within a metal tube. An observation slot is cut out of one side of the latter. The glass tube is slightly conical in bore, the larger end being uppermost. Inside the tube is a light wooden bobbin or float, 'which is im- pelled up the tube by the stream of gas entering at the bottom. The higher the float rises, the wider is the annulus between it and the tube. The float settles at a point in the tube at which the force of impact of the oxygen on its under surface is equal to its weight. The scale, in litres per minute, is etched on the glass, and the flow is recorded by the reading oppo- site the top of the bobbin. Owing to inequalities in the bore of the glass tube, each instrument has to be calibrated separately, and the graduation is very irregular. Briggs’ litre meter resembles Draeger’s in that a moving bobbin serves as indicator, but differs from the German form in having a uniform bore glass tube in place of a conical tube. It was designed to meet the present-day difficulty of getting conical tubes in this country. Testing the Relief Valve.—An automatic blow-off valve requires frequent attention, as its proper adjust- I t t, til Fig. 1. ment has a good deal to do with the successful working of a rescue apparatus. It is easily tested by connect- ing to a water gauge one opening of the bag or tube to which it is fitted and blowing into the other open- ing until the valve operates. The gauge should then register about 4 in. of water. Testing Injector Apparatus.—The injector of the Draeger and Meco apparatus is designed to induce a static pressure difference of 4 in. of water when passing two litres of oxygen per minute. An indirect but useful mode of testing the oxygen discharge is therefore to attach a water gauge to either the suction or discharge side of the injector and then to turn on the oxygen. Most instructors very rightly insist on each membei’ of a brigade applying the water gauge test before donning his apparatus, but, valuable though it is, that test is not in itself sufficient. A more detailed scrutiny should be made from time to time, and especially after the “automat” has been overhauled. Any of the four meters above described may be used in determining the oxygen feed, the delivery side of the automat being connected to the gauge and the suction side being closed by a screw cap. (To be continued.) Coal and Iron in Ireland.—At a meeting of the Irish Sub-Committee of the Parliamentary Committee on Irish Transport, held in Dublin last week, Mr. William Tatlow, B.E., representing the Arigna Coal Mining Company, Co. Roscommon, said that his company was engaged in ex- ploiting the minerals in the Arigna Valley to the west of Lough Allen. Coal, iron ore, fireclay and flagstones were the minerals they produced. Coal and flagstones for the moment were the chief productions. Iron ore and fireclay could not be worked owing to -want of transport. A railway was being constructed to connect the coal mines with the Cavan and Leitrim Railway. The iron ore and fireclay could only be developed through the waterways of the Shannon. The output of coal had increased from 82 to 120 tons per day, and there would be a further increase when the connecting railway got into operation. The largest quantity of coal put out in one year was 12,000 tons. There were about 18,000,000 to 20,000,000 tons of coal in the locality. Iron and Steel Institute.—At the autumn meeting of the Iron and Steel Institute, held at Westminster last week, Sir Robert Hadfield, past president, commented upon the need of economy in the use and manufacture of steel. Prof. W. A. Bone suggested that the institute should appoint a committee to consider and to represent the views of the industry upon economies which might be at once effected, and make recommendations to the Coal Controller and such authorities as had the matter in hand. The meeting approved of the formation of a com- mittee. Mr. Cosmo Johns introduced a report upon the “ Standardisation of Tests for Refractory Materials,” which had been prepared by a committee of the refrac- tories section of the Ceramic Society. He pointed out the need of having more speedy tests of a unified nature with which to judge the suitability of these materials rather than by the slow testing of their efficiency by observation of their behaviour under service conditions. Many other papers were submitted. PORTABLE AUTOMATIC TRIMMING CONVEYOR.* The process of “coaling ship,” which consists not only in getting the coal on board but in conveying it to and filling the various bunkers, termed “trimming,” is always an operation requiring a large amount of hand labour. Part of the operation consists in trans- ferring the coal from barges or other craft, or from shore to the reverse; many mechanical devices are used, but for filling and trimming of bunkers by mechanical means little has been done at present. The portable automatic trimming conveyor has been designed with the purpose of handling the coal with the minimum of labour, trimming it into all the bunkering spaces provided in mail and cargo steamers, reducing the cost, and displacing the hand labour required in the present bunkering system. Fig. 1 illustrates the arrangement of the plant, which consists generally of a series of short self-con- tained conveyors, usually three in number, but depend- ing upon the length of the bunker, suspended from a pair of rails attached to the centre of the deck beams inside the bunker upon which the conveyors are free to travel longitudinally. The coal is delivered at one end of the series of conveyors by means of a shoot from the deck above, and is discharged at the other end by the trimming or front conveyor. This conveyor is provided with a lateral movement, so that the coal may be distributed over the whole width of the bunker, and is inclined sufficiently to throw the coal high enough to fill the bunker up to the top. The conveyors are each driven by an electric motor situated inside and forming part of the end driving drum or terminal. The necessary lateral and longi- tudinal movements of the trimming conveyor are operated by mechanism from the driving motor, and both are automatic, the lateral movement being con- tinuous and the longitudinal movement being depen- dent upon the action of an ingenious device attached to the front of the conveyor and consisting of a hanging plate or shield, which is caused to move by the action of the coal piling up, thereby making an electric con- tact, which sets in motion a drum and winds back the train of conveyors. When the end or tail conveyor has been backed beyond the delivery shoot and is no longer required, it can be removed and fixed in another position. Coaling can then commence in another bunker or several trains can be fitted up from a central delivery shoot, and the whole of the coaling proceed at the same time. When both sides of the ship must simultaneously be coaled, conveyors can be laid across the decks or slung from gantries or cranes to the delivery hatch. In fact, they can be adapted in any direction where material has to be shovelled, wheeled, or carried. Fig. 2 illus- trates the trimming conveyor only. Fig. 3 illustrates a portable conveyor of the same general design as the trimming conveyor mounted on swivelling castors for moving about the ship’s deck, wharf, warehouse, or any other place where material has to be moved. These conveyors are also self-contained, and can be made in any desired length, and any numbei’ can be fitted up end to end, making a continuous train possibly several hundred feet in length. The special feature of this conveying plant is the electric driving drum, of which the complete machine is illustrated in fig. 4. This driving drum consists of an electric motor of suitable horse power, which can be wound for any commercial voltage for either direct or alternating current. The whole of the outer drum which forms the belt pulley revolves and receives its power from an internal machine-cut gear wheel fixed to one of the end brackets that carry it; these brackets run on standard roller bearings. This internal gear wheel is connected by suitable spur and pinion, with a pinion fixed on one end of the sleeve, on which is also mounted the armature of the motor. This arma- ture and driving pinion revolve on a hollow shaft, to which is keyed the yoke and fields of the motor. The hollow shaft serves the double purpose of pro- viding at one end a reservoir for the lubricant for the armature sleeve and gearing, and at the other a channel and protection for the cable connections. Both end brackets of the drum are solid, so that the machine becomes a totally enclosed motor, protected from dust and damp, enabling it to be used under any weather conditions or in any situation. Fig. 5 illustrates the * Jones patent.