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Coal Dust. The Hutton Seam in the 4th North District is not a very dry and dusty seam, and wet conditions are met with at times, but the air picks used by the hewers produce coal dust, the finest of which is air-borne and deposited at the return ends of the faces, where the loading points in both conveyor gates were placed. This dust, added to that deposited during coal loading operations, would thus increase the difficulty of maintaining these places constantly in compliance with the Coal Dust General Regulations, 1939.

There was evidence to show that the management were alive to the importance of dealing with the coal dust at these points. On 16th August 40 bags (4 tons) of shale stonedust were spread in the district, and after the roadways had been cleaned up on the nights of the 19th and 20th August a further 40 bags of stonedust were spread throughout the roadways, including the two loading gates, on the following night of 21st August ; but it is to be noted that subsequent to the treatment the Straight East face had been worked on the first shift and the 2nd East face on the second and third shifts; and the cleaners-up were just about commencing their work in both gates when the explosion occurred.

Four days after the explosion, nineteen samples of the dust on the roadways in the district were collected by an Inspector of Mines, and the details of the results of the analyses of these samples are given in Appendix IL Admittedly, in view of the blast which had swept the district these results do not represent the conditions obtaining before the explosion, but they do, in my view, give some indication that the floor of the conveyor roadways as a whole was in doubtful compliance with the Regulations at the time. However that may be, the disquieting fact remains that a coal dust explosion swept throughout all the existing and disused conveyor roadways in the district, with the contrasting difference that neither of the conveyor faces nor the hand-worked faces and roadways were affected; and this exemplifies the additional hazard from coal-dust brought about by mechanised mining.

Furthermore, a sample of the coal dust ground from the Hutton Seam was found on test for inflammability at the Research and Testing Branch at Sheffield to require 69 per cent. total incombustible matter content to prevent inflammation, as compared with the 65 per cent. minimum required for this seam by the Regulations.

The stonedust in use was ground at the colliery from shale from the underground workings and a sample tested at Sheffield for fractionation and dispersability was found satisfactory. In my view the evidence shows this stonedust had functioned satisfactorily in arresting the explosion.

The accumulations of dust apparently rich in coaly matter found on the floor after the explosion in all the disused conveyor gates indicate that these roads should have been cleaned up more thoroughly. In this connection I would point out that No. 3 of the Coal Dust Regulations 1939, in requiring the taking of such measures "for the prevention, suppression, collection and removal of coal dust and for treating it with incombustible dust or in any other manner approved "includes" every road or part of a road which is accessible"; and that No. 7, in calling for the systematic clearing of the dust on the floor of every conveyor road, includes "the space beneath the conveyor ".

The arrangements in respect of frequency of treatment in the 4th North District of the working roadways in the district were good up to a point, but it may well have been (and I think it probably was the case) that after two coaling shifts had been worked there since it had been last treated the 2nd East gate was not up to the required standard.

Dust sampling had been carried out in accordance with the Coal Dust Regulations, but monthly sampling on conveyor roadways, especially in the vicinity of the loading point, where the conditions can deteriorate considerably in the course of a loading shift, clearly gives no real guide to the position in respect of coal dust.

Under the existing Regulations conveyor roadways are not necessarily sampled each calendar month; and therefore, in effect, treatment is decided on the result of a visual inspection. It is true that in many instances where very dusty conditions prevail the treatment is systematic, but this may well not be sufficient, and managers should make it a rule to have these roadways sampled at very frequent intervals to provide themselves with a truer picture of the position and so enable them to decide on the extent and frequency of treatment necessary to ensure compliance at all times with the Regulations.

In this connection, however, it is necessary to point out the danger of exposed layers of coal dust. Experiments carried out at the Research and Testing Branch with a highly inflammable coal dust (similar to the Hutton Seam) have established that a mild explosion, initiated by an igniting source of low violence-the conditions which obtained in this explosion-may be propagated by a coal dust which it raises from a surface layer only 4/100ths of an inch thick, even where the coal dust rests on a stone dust deposit nine times its own weight ; and this result was obtained on separate tests with three different types of stone dust. This danger can only be countered by the frequent application of stone dust in small amounts.

There is no immediate remedy other than the continual cleaning up and application of stonedust at these places, except that the amount of breakage and spillage of the coal while being conveyed and transferred should be reduced to a minimum; and shrouding the delivery and transfer points, and the use of water sprays, should be adopted more generally.

But there is no doubt that the only solution (known at present) to the problem lies in the application of water for the suppression of coal dust at the source either in the form of infusion of the coal face, wet cutting or spraying; including, where used, the fitting of water feed to air picks, which is now a practicable proposition.

The chain type of conveyor used in 4th North District undoubtedly created additional coal dust, due to the grinding action of the chain on the conveyor pans and to the escape at the pan joints of some of the dust on to the roadways.

Firedamp Detectors. I have already mentioned that there were no firedamp detectors other than the deputy's oil lamp in the 4th North District on the shift of the explosion. Safety lamps were not required in any of the seams at this mine by virtue of Section 32 (1) (a) of the Coal Mines Act, and detectors of the automatic type were not in use, but the other requirements of the Coal Mines General Regulation s (Firedamp Detectors) 1939 were applied to both safety lamp sections and to the 4th North District, which, it should be recalled, was in the open light section of Morrison North; and high candle power flame safety lamps were carried in addition as gas detectors by appointed workmen in the proportion laid down by these Regulations.

It has been an instruction for some years past at this mine for each deputy to record the names on his statutory report of all persons carrying gas detectors, and as far as the matter can be checked up with the lamproom records this rule was carried out generally, including the 4th North District.

I am not able to account for the apparently strange coincidence that none of the men had gas detectors in this district at the time, but it may well be not unconnected with the earlier and varying times of the commencement of the night shift on Fridays and with deputy Estell's late arrival on duty. The lampman on shift had apparently without question given the workmen the only type of lamp they had asked for. Minto, a survivor working in the Straight East gate, states that his mate Westgarth had a flame lamp on the back shift, but he could not say why he had not brought one on the night shift.

However, careful observation for firedamp seems hardly consistent with promiscuous smoking and I think it unlikely that the presence of gas detectors. in the district would have obviated the explosion.

One of the workmen appointed to use a gas detector stated at the Inquest that he had seen diagrams of gas caps but had never seen a real gas cap. Mr. Vernon Richards, Workmen's Inspector, suggested that as far as possible arrangements should be made to enable these persons to see a real firedamp cap in the pit on a reduced flame. This may not be practicable in some instances, but more might be done in this direction with advantage, and r commend the suggestion to managers.

Searching of Workmen. It is doubtful if safety lamps were legally required in any part of this mine, but in any event Section of the Act was applied. in its entirety to all sections or districts in which safety lamps were in use, including the 4th North District, as a voluntary precaution by the management; and the standard selective system, with a quarterly general search (which was last carried out throughout the mine on 28th July), had been in force since 1941.

The general arrangements for searching have since been checked and found satisfactory but the usual complications arising from " mixed" lights were present in respect of the Morrison North shaft, where the 4th North District workmen using safety lamps intermingled with other workmen of the open light areas. This difficulty was overcome by fixing warning notice boards along the haulage road leading to the 4th North District, beyond which open lights and contraband were prohibited, and many of the workmen were searched at this point by the overmen, who were responsible generally for searching all the main shifts of workmen at the mine; but owing to continuous working and the different times of commencement of the shifts in this district from the normal working shifts elsewhere overmen were not always available at this point, and the deputies' kist was regarded as the main searching station for the 4th North District. Here a selection of the men were searched by the deputy on shift, who admitted them to their work and who recorded on his statutory report the number of persons he had searched.

Following an explosion of firedamp at Watergate Colliery, Durham, on 3rd July last, involving two lives and due to illegal smoking, the Group Agent had impressed on all his, managers the need for thorough searching, and this in turn was stressed with the officials and the deputies, but the amount of contraband found after the explosion proves how futile and ineffective the method of searching was, at any rate on this night shift in the 4th North District. Two of the victims whom deputy Hebden stated he had searched at the kist were afterwards found to have contraband on them. It can only be concluded that some members of the night shift were in the habit of smoking at their place of work and that the deputies must have been aware of this; in fact, the finding of so many spent matches at their kist suggests that they themselves were guilty of this practice. Furthermore, it is difficult to see how the overmen concerned could have failed to detect smoking carried on to such an extent. The fact, however, that spent matches had been replaced in some of the tins of contraband indicates that some of the men, at any rate, had been careful not to leave any evidence of smoking behind.

The method of searching was clearly much too perfunctory in respect of the 4th North district, but admittedly no degree of searching can be really effective without the co-operation of the workmen concerned. In this instance it is difficult to avoid drawing the conclusion that there was connivance in this matter of smoking between the deputies and the workmen. It is, I am afraid, not unlikely that the under-officials, who would be fully aware the district was on safety lamps for a reason not connected with safety, failed to do their part in stamping out the natural tendency to smoke of workmen used to open light conditions.

This deplorable state of things was certainly not consistent with the high standard of safety and discipline which has always been the aim of the management of this group, and I attribute this lack of discipline in the 4th North District revealed by the explosion to have been a consequential effect of "mixed light" conditions.

Ventilation arrangements. The single cloth on the Straight East gate to separate the main intake from the North Heading return airway was bad practice and not in compliance with No. 10 (1) (b) of the new Ventilation General Regulations which came into force on 1st August last. Arrangements for splitting the air were practically completed and this would have cut out the North Heading as an airway, but owing to its proximity to the main intake this connection with the return airway should have been dispensed with at a much earlier stage in the development of the district. It is true the Wembley connection had, meanwhile, established the ventilation of the 2nd East face and the other inbye faces but it had the effect of placing the Straight East between two very heavily regulated airways and any disturbance of the cloth would therefore have a more serious effect on the ventilation of this part of the district ; and I do not think this aspect of the position was fully realised by the officials. Admittedly, the cloth was found apparently unaffected by the explosion, but nevertheless, I consider that it may well have had some bearing on the occurrence of firedamp in this part of the district. The uncertain character of the regulating arrangement at the Wembley connection is also open to criticism.

The availability of an abundant supply of fresh air (due to the proximity of the district to the upcast shaft) doubtless accounted for the fact that canvas cloths only were in use for coursing the air current around the district.