September 17, 1915. THE COLLIERY GUARDIAN. 573 number of compressor strokes required to maintain normal pressure when no air is being used, as a propor- tion of the compressor strokes under normal working conditions. One almost hesitates to commit to print a record of the observed facts. .At the colliery referred to in example (1), a single joint in the main pipe leading from the receiver to the shaft was noticed to be leaking; at the week-end the joint beyond it was blank-flanged, and the defective joint was found to be passing air at a rate equivalent to the value of <£500 per annum. In another method of ascertaining the approximate rate of air leakage, the cubic capacity of the whole system of pipes and receivers is calculated; the loss of free air during one minute is equal to the difference between the volume of free air contained at the pressure observed at the beginning and that contained at the pressure observed at the end of one minute. The loss ot volume is that due to the mean pressure during the minute of observation. Any leakage through the valves of the compressor is included in this test. S so Fig. 5.—Curves of Leakage against Time. Fig. 5 illustrates characteristic examples of diagrams of rate of fall of pressure due to leakage from pipe systems of which all outlet valves were closed. These curves illustrate graphically the declining rate of loss of air as the pressure falls; the influence of high pressure in increasing the losses by leakage is referred to later. Apart from the coal cutters and trailing hose, the principal sources of leakage are :—(a) defective pipe joints; (b) defective valves and cocks; and (c) open receiver drains and blow-off cocks. Defective Pipe Joints.—Defective pipe joints are undoubtedly the chief source of leakage. The difficulties of maintaining airtightness of a large number of joints in a rigid system of piping subjected to the disturbances and dislocations that attend the movements of the strata in which the underground roadways are* formed are obvious. While the nature of the conditions which adversely affect the underground pipe joints are fully understood, there are certain points in connection with the above- ground mains, and the pipe column in the shaft, which are not adequately appreciated. Compressed air when it leaves the receivers is hot, and the main pipes are heated to a considerable distance. Fig. 6 gives an example of the temperature gradient measured outside the pipe along a main air pipe. It is clear that pipe lines which are subjected to considerable changes of 150" Inocai frTMOS aHERlC iiMPJVaTUhE. Fig. 6. z Fah 2.00 ieo 180 2 no. 160. ujllSO. ^b+o. I'W- ^rzo. S"O- H»OO. O 90. J 80. 200 Md 60 50 40 SO 20 300 350 400 +50 500 550 600 Yards Curve showing temperature-gradient taken externally along an air-pipe from the receiver into the mine. Pipe, 10 in. in diameter, carrying 2,000 cu. ft. of free air per minute. temperature, due to the alternating periods of work and rest, ought to have expansion joints to compensate for movement of the piping. Provision of expansion joints and the exercise of greater care in so supporting the piping as to relieve the joints from unnecessary strains would soon be repaid by the saving of compressed air. Another cause of trouble with the joints of the piping on and near the surface is that the indiarubber packing of the joints is attacked and dissolved by oil carried from the compressor cylinders by the air—a process which is accelerated by changes as to temperature and moisture. Leakage from Valves and Cocks. — There are two sources of leakage from valves and cocks :— (a) past the valve spindles, because of defective packing; and (b) past the faces or bodies of the valves and cocks, because of the surfaces being worn or abraded. The first is to be cured by renewing the packing in the glands, and the second by grinding the valves on their seats. Leakage from Drains and Blow-off Cocks.—The drainage of water from the underground pipe system without incurring loss of air is a difficult problem. In some cases differences of level facilitate drainage, and in others add greatly to the difficulties. It is important that free water should be tapped from the piping, and there are three methods of effecting this :—(a) Auto- matic traps; (b) collection of water in receivers and its periodic release; and (c) by leaving the drain-cocks slightly open. The last-named method is usually adopted. This method of leaving the drain-cocks more or less open is the most simple, the most certain, and the most wasteful. The men who open the cocks have no means of knowing exactly the area of the outlet they provide, and if they had, they would still be ignorant of the volume of air escaping; they therefore make sure that the cocks are sufficiently opened. In the absence of valves to isolate branch mains, the leakage from receiver drains on the branches is continuous during the whole time that pressure is maintained in the piping, and is actually increased by the higher pressure in the pipes when in-bye machines are not at work. The best cure is to provide receivers of ample size to store all the water that may accumulate in a shift, and to draw this off at the beginning or at the end of each shift. Other Sources of Waste.—At many collieries extrava- gant practices obtain, amounting to waste, in the use of compressed air. The ventilation of headings by com- pressed air is not infrequent; the practice is no doubt very convenient, but its cost is not counted, and those who use it have no measure of the expenditure they incur; normal practice, not cases of emergency, are referred to. The legitimate method of using com- pressed air for auxiliary ventilation is to use it in small volume through an inducing nozzle, and thereby to inject or eject through an air duct a flow of air in the required direction, or to use compressed air for driving a small turbo fan. At one small colliery nearly the whole pit was ventilated (and very ineffectively ventilated) by compressed air, and coal-cutting was reduced to a joke. Another practice, less reprehensible but still extravagant, is to use compressed air for clear- ing gas from headings on the occasions of shot-firing. (To be continued.) THE BRITISH ASSOCIATION. DISCUSSIONS AT THE MANCHESTER MEETING. [From Our Own Correspondent.] The annual meeting of the British Association, held at Manchester during the past week, was exceptionally successful, many of the discussions being concerned with topics of high national and technical interest. Relationship Between Employers and Employees. The relationship between employers and employees not unnaturally received considerable attention at the various sectional meetings, and although colliery interests were not specifically mentioned, nor did any representative of the coal mining industry take part in any of the discussions, never- theless, it is reasonable to assume that recent events in the coal mining industry actuated many of the speakers. The first direct reference to the matter was by Dr. H. 8. Hele-Shaw in his presidential address to Section G. Speak- ing of the need for the enormous production of munitions, Dr. Shaw said that probably the most serious feature in our national life to-day was the relation of employer and workman. He proceeded :—“ It is hopeless, so long as such ideas prevail which seem to do at present, to think of any sound organisation of our industrial system taking place, because the interdependent parts are not arranged (and can never be arranged until we change radically) with respect to the whole. . . . I am the last man to put this evil down entirely to the working man. I know individually he is just as. capable of patriotism as any other class. Get him by himself, even the men whose strikes have caused such despondency in the minds of our Allies, and who have seriously jeopardised the very existence of the country, and you will find (except in the sort of case to be found in all classes of society), that he, as an individual, is willing to make sacrifices, and if necessary to give himself for his country. The truth is that the canker which is eating the heart out of our industrial life is due to an entirely wrong attitude of mind. For instance,, however much we may sympathise with men who see a loss of employment in the introduction of labour saving machines, some means should be found by which they can share the benefits to the State and to their employers by the introduction of such machines.” Dr. Hele-Shaw considered that the questions of piecework and overtime must be seriously considered by the State, and not allowed to become the subject of disastrous disputes. Then there was the question of a standard wage. The trade unions had a great opportunity of placing their country and themselves in a leading position amongst nations if they would courageously grapple with a great problem by recognising degrees of merit and corresponding degrees of payment. They had recently seen the Prime Minister and other leading statesmen struggling, sometimes in vain, to bring large bodies of men to a reasonable state of mind. Was not this a case of Nemesis overtaking us for having in so many cases pandered to the selfish instincts of large bodies of men in order to secure their votes, instead of sternly telling them unpalatable truths? Prof. W. R. Scott, president of Section F (Economic Science and Statistics), did not directly deal with this matter in his presidential address, but a general discussion on means for promoting industrial peace followed its reading. Sir Charles Macara said that the efficient co-operation of the industrial, commercial, financial, scientific, transport and labour interests of the Government at an early stage of the war would have enabled our enormous resources to have been brought into requisition from the very commence- ment of the war. It was unfortunate that the services of men who had led great organisations of capital and labour had not been taken advantage of by the Government to anything like the extent they should have been. For some reason which it was difficult to understand, the Industrial Council was only utilised to a very limited extent before the war, and notwithstanding the very considerable industrial unrest that had occurred since the war, it had not been utilised at all. Another matter which was equally inexplic- able was that the result of an extensive enquiry into industrial agreements and their observance which was deputed by the Government to the Industrial Council, and which occupied 38 long sittings in 1912-13, had never been utilised.. A perusal of the report that was issued proved conclusively not only the desirability of, but the absolute necessity for, the thorough organisation of both capital and labour, and that where this obtained disputes were usually settled between the parties themselves. The main obstacle to the perfecting of these organisations was the selfishness of a small minority of both employers and workpeople, who remained outside the various organisations, but who did not hesitate to take full advantage of the public-spirited and self-sacrificing work of the majority. The enquiry by the Industrial Council also demonstrated that compulsory arbitration for large bodies of men by legal enactment was impossible, and therefore it should never have been included in the Munitions Act. He held strongly that the interference of politicians with industrial disputes was calculated to generate bitterness between capital and labour, and often led to inconclusive settlements which were against the best interests of the industries. The employers had the idea that this interference placed them at a disadvantage, and that such a feeling should exist, although the work- people might gain an immediate apparent advantage, was ultimately prejudicial to the real interests of industrial peace and the national welfare. In this connection he wished to emphasise that a large proportion of the gross earnings of industry goes in the payment of labour and of the expenses necessary to the running of the industries, and even under normal conditions, there is only a small margin that is left to remunerate those who have invested their capital. In the event of such a crisis as the present, this might not only vanish, but there may be a diminution of capital, and it must be borne in mind that the employers* resources are not unlimited. The effect of the war on industry had been most varied, and to deal with the wages question without taking into consideration the varying conditions was obviously unfair. A thorough investigation into all the circumstances is absolutely necessary before giving any award in a wages dispute, instead of, as is too frequently done, ignoring these conditions or splitting the difference. It would be difficult to conceive any better method for pre- venting or settling disputes than such a body as the Industrial Council. To this council the Government should refer all disputes that the parties themselves fail to settle, and the decision should be published. Any refusal of either of the parties to a dispute to submit their case to a tribunal composed of an equal number of experienced representatives of capital and labour with a non-political chairman appointed by the Government, would be strongly presumptive evidence against the fairness of their demands, and the impression made on those whose interests are seriously prejudiced by the dispute, and on the public generally, is the only com- pulsion possible, and it should usually be effective. A number of speakers took part in the debate, including Sir Hugh Bell, who gave a few figures as to the margin of profit left in his own particular case. Putting it in round figures, he said that for every ton of steel work, 70-75 per cent.. of the revenue from it represented labour. Of the remainder only 10 per cent, was left of profit, but from this he had adopted the practice of allocating 3 per cent, as reserve for depreciation, leaving on an average 7 per cent, as the net profit. Therefore, it would easily be seen that 10 per cent, increase of wages to the men would place the employers who were on a similar basis to himself, in a very serious position. He agreed that workers should get their full share of wages, but they should give full value in return by way of labour. At the same time the position as between labour and employer generally was not so hope- less as some might imagine the fact implied. He supported Sir Charles Macara’« suggestion of what might be termed compulsory conciliation. There were a number of other speakers, but no resolution was submitted, and it remains with the committee of the section to take such further action as may be thought necessary. Fuel Economy and Smoke Prevention. Before Section B (Chemistry) a discussion took place on smoke prevention. This was opened by the President (Prof. W. A. Bone) who had also referred to the subject of fuel economy in his presidential address, a report of which appears on page 585. Mr. E. D. Simon (chairman of the Manchester Air Pollution Advisory Board) said the damage done in Salford and Manchester by smoke amounted on a reasonable estimate to about id,000,000 per annum, but unfortunately the public would not believe this. Nevertheless, it was felt that a research upon damage done by smoke was less important than the investigation of the means of abating it. Problems affecting both factory and domestic smoke, such as all general problems of smokeless combustion, surface combustion and the electrical deposition of soot and dust, were lines of research which might possibly revolutionise matters in smoke abatement, and could not be over estimated. The work required in this connection he divided into four main branches. First, the variations in efficiency as regards radiation, heat production and smoke between existing types of coal burning grates were enormous. Our knowledge in this direction was very rudimentary, and offered much room for further research. Secondly, there was the possibility of the production at a commercial price of a semi-coke or coal which would burn as cheerfully as coal and as smokelessly as coke. He understood that a new company had been formed to sell such a product, and hoped it would be successful. Thirdly, there was the adaptation of open fires for burning coke, and finally, perhaps most important of all, the improvement of gas fires. The Manchester committee having considered these various lines of research, had undertaken two researches which it decided to join in the national investigation as to the deposition of soot, and was measuring at ten different stations, whilst the second research was to fit up a room at the School of Technology for the purpose of carrying out tests of various kinds of domestic heating appliances. It was proposed to undertake measurements of radiant heat, flue gases, to test gas fires for leakage, and any other tests which experience might dictate. Promising attempts were already being made to devise a standard method for measuring the total radiant heat given out by a fire. It should be possible to make a reasonable charge for tests made or advice given, and thus the department should become self-supporting. The most hopeful line of progress was in the direction of endeavouring to secure that bituminous coal should not be burned as such until after conversion into products which could be smokelessly consumed. With regard to factory smoke, only moderate progress could be made at present, but the increased use of producer gas showed that something could be done. It might be that a central committee of the British Association could be appointed to co-ordinate the work throughout the whole country. Prof. W. W. Haldane Gee described generally the work that has been done in Manchester, and the direction in which the central committee had used its powers.