cannot be arrived at, but in the face of the evidence one is confined to the consideration of possibilities which are only speculations, the further pursuit of which can serve no useful purpose. CONCLUSIONS. Statutory Requirements.-Nothing was revealed at the inquiry to indicate that Part II of the General Regulations of 30th July regarding Spontaneous Combustion was not complied with. There was a suggestion by counsel appearing for the North Staffordshire Miners' Association that General Regulation 9 (1) was was not observed, but the suggestion was not pressed. The Regulation reads as follows: "On the appearance in any part of the mine of smoke or other sign indicating that a fire has or may have broken out below ground every workman other than those necessarily engaged in dealing with the emergency shall be withdrawn from the ventilating district or districts affected There are further provisions in respect of re-admission of the workmen after withdrawal but since no question arises on them they are omitted. As a matter of fact, the men on the morning shift were on their way out of the mine while the investigations into the peculiar smell which had arrested the attention of Forrester and Hughes were being made by the undermanager, Lowe, and the overman, Wilcox. The result of this investigation was negative, i.e., both Lowe and Wilcox, and also Forrester, were quite confident that none of the indications defined in the Regulation were present and the afternoon men were, therefore, allowed to proceed to their places. It is true this investigation terminated at the top of Wakefield's back dip, and, although Lowe admitted in cross-examination that after this experience he would in similar circumstances make a more complete investigation, he had what in my view seem to be adequate reasons for his action. He had already seen the day fireman who reported everything in order; none of the day shift workmen made any complaint; he had a report from Wilcox that he had just completed an investigation and found nothing; and, finally, he had the statement of Forrester that he too was by that time convinced that the smell which he had previously noticed, but which he could not define, had disappeared. The undermanager, Lowe, also testified that this was not the first occasion upon which he had had reports of smells which on further investigation had proved to be unfounded. I do not consider, therefore, that there was failure on the part of Lowe to observe the provisions of the Regulation quoted above. No suggestion was made by any of the parties represented at the Inquiry that any other statutory requirement had been neglected. It is my duty, however, to report that on the evidence of the day fireman, George Sherwin, the firemen's inspections were not made strictly in accordance with the provisions of Section 64 (1) of the Coal Mines Act, 1911, inasmuch as the inspection prior to the commencement of work in the afternoon shift was started at 12 noon and completed at 2 p.m., while the persons forming the shift did not start to descend the pit until 2.10 p.m., so that it was impossible for any of them to arrive at their working places before about 2.30 p.m. In short, the parts of the mine in which the afternoon shift workmen had to work were not inspected within two hours immediately before the commencement of work in the shift. In a mine such as this-gassy and liable to sudden spontaneous heatings-the working places should be left unobserved as little as possible, and the "two hours" period so far from being increased should if possible be reduced. Observations on the Method of Working.-Reference has already been made (see page 6) to the practice of flooding the goaf with firedamp, ostensibly in order to prevent active combustion, with the production of flame therein. To be effective in this respect, the atmosphere throughout the goaf must contain not more than about 14 per cent. of oxygen and, unless blackdamp is present in considerable quantity not less than about 35 per cent. of firedamp as diluent. In practice, it is evident that, while in some parts the atmosphere may be such as to give an ample margin of safety on these figures, in other parts the safety point cannot be constantly maintained. For instance, it is essential that the atmosphere in the working places shall be adequately ventilated in accordance with Section 29 of the Coal Mines Act, 1911. To this end, an attempt is made so to regulate the current of air circulating in the working places that while they are substantially free from inflammable gas the goaf beyond is left unventilated. Obviously, no accurate check can be kept on the composition of the atmosphere beyond the working places, the goaf being to all intents and purposes inaccessible. The air on the fringe of the goaf can be tested by means of the safety lamp, but these tests are limited to the indication of comparatively small percentages of firedamp, since a safety lamp cannot be used to indicate any percentage higher than the lower limit of inflammability of the gas, viz: about 5 per cent. Passing from the lower of these two limits, viz: fresh air practically free from firedamp in the working places to the upper limit, if it is actually reached, of a minimum of 35 per cent. somewhere in the goaf, there must be a progressive increase in the percentage of firedamp in the atmosphere, since the laws of diffusion preclude a definite plane of demarcation between two atmospheres in contact containing varying percentages of firedamp. It is clear, therefore, that surrounding the working places, but at a more or less indefinito distance from them, there must be a zone in which there exists an explosive mixture of firedamp and air. Should flame break out in this zone, or a source of ignition be introduced into it, an explosion is inevitable. Further, it is to be noted that beyond the explosive zone containing the wide range of firedamp and air mixtures between 5 per cent. and about 15 per cent. of firedamp which are the lower and upper limits of inflammability of mixtures of firedamp and air, there is a second zone containing the still wider range of percentages between 15 per cent. and 35 per cent. The percentages of firedamp in this zone are above the higher limit of inflammability and the atmosphere is, therefore, not explosive; but since it contains less than 35 per cent. of firedamp, the heating of coal can proceed in it up to the point of active combustion when a red heat is attained even if actual flame is not produced. This zone and the explosive zone seem likely together to form a fairly wide belt containing the very wide range of atmospheres in which spontaneous combustion can develop. The method of fighting gob-fires by attempting to create an extinctive atmosphere in the goaf is, therefore, subject to serious and, in practice, unavoidable limitations. At its best it is largely a matter of chance whether or not a fire develops in conditions of grave danger. This reasoning leads me to conclude that the comparative imm1nity from explosions in the past has not been due to the benefits. which flooding the goaf with firedamp is supposed to confer. Indeed, I am inclined to doubt whether many more heatings than have occurred would have occurred if working by some other method had been in operation. In my opinion, the efficacy of the "Rearer" method as applied to seams subject to spontaneous heating lies in the existence of the limited number of openings into a panel and the concentration of the return air in one airway, so that the indications of incipient heating have been able to be detected at an early stage in their development and the affected. area has been able to be speedily sealed off before more dangerous conditions could arise. As regards the application of the "Rearer" system in this particular case, reference to the plans, Plates 1 and 2, will show that near the top right hand corner of the goafed area there are two roadways with stoppings in them. Evidence was adduced to prove that the stoppings were regularly inspected and that no indications of leakage through them were found. There was also evidence by Forrester and Hughes that the smell which they endeavoured to trace to its source did not come from these stoppings. Nevertheless. I am unable to dismiss from my mind the suspicion that these openings had something to do with the presence of the unusual smell in the West Slant and its absence from the working places and the return airway of Wakefield's district. However well the stoppings were built and maintained they could not be as impervious to the percolation of gases as a solid rib of coal. Even a slight leakage of firedamp at that point would, over a prolonged period, have a material and detrimental effect on the composition of the atmosphere in the goaf. Further, it is not unreasonable to suggest that the indications of incipient heating might also have escaped in that direction instead of being, as is essential to the method of working, concentrated in the current in the air heading and the back dip. These considerations lead me to say that these openings were ill conceived and it would be advisable in future to avoid similar openings, if for no other reason than to be consistent. As regards the general question of the safety of the "Rearer method of working, in view of the comparative success of the method of working in the past, I am unable now to condemn it out and out, but clearly it is a method which leaves much to chance, and the time has come, I think, when the possibilities of other or modified methods of working should be further explored--methods in which operations can be carried on with a greater degree of certainty as to the condition of the atmosphere in the goaf. I am glad to be able to report that in reply to questions regarding alternative methods of working, the Agent, Mr. J. R. L. Allott, stated that the matter is being considered and he had in fact visited mines in Germany, where similar difficulties are encountered, with a view to studying the methods of working in vogue there and to see if any of them could be adapted to suit the conditions at Birchenwood. I understand that the Spontaneous Combustion Committee is directing its energies to evolving means, depending upon systematic sampling and analysis of the return air, by which information of incipient heating may be obtained before it reaches the stage at which gob stink appears. I hope their work will be successful, for it would remove a good deal of uncertainty and add greatly to the safety of working in seams of this character. In conclusion, I desire to acknowledge the assistance given to me. by the representatives of the various parties present at the Inquiry, which was conducted throughout in a friendly spirit and with a desire if possible to discover means by which similar occurrences may be prevented. I have the honour to be Sir, Your obedient Servant, F. H. WYNNE. APPENDIX I. LIST OF WITNESSES. (Arranged in alphabetical order.) James R. L. Allott, Managing Director and Agent to the Kidsgrove Collieries, Ltd. Alfred Duncan, Physician and Surgeon. Gerrard Forrester, Assistant to Manager. A. M. Henshaw, Mining Engineer. Albert Hughes, spare Fireman. James Kelsall, Collier. George W. Lowe, Undermanager of Birchenwood Colliery. C. B. Platt, Superintending Testing Officer, Mines Department. W. H. Sims, Collier. William Upton Staveley, Manager of Birchenwood Colliery. J. L. Swingewood, Loader. E. Threadgold, Hooker-up. E. H. Vallis, Assistant to Manager. A. Warren, Fireman. A. Whalley, Fireman (afternoon shift). R. V. Wheeler, D.Sc., Director of Experimental Stations (Safety in Mines Research Board). G. Wilcox, Overman. APPENDIX II. LIST OF PERSONS KILLED. Thomas Growcott. Body recovered 31st March, 1926. William Owen. Body recovered 31st March, 1926. Daniel Swingewood. Body recovered 23rd February, 1926. Leonard Caton. Body recovered 18th December, 1925. I. Ball. Alive when rescued, died from injuries on 27th December, 1925. (226-11b) Wt. 9685-3769 1000 9/27 H. St. G. 3 " |