Scottish Mining Website

Mines Department,
Home Office, Whitehall, S W. 1.
12th March, 1919

Sir,
I beg to state that, in compliance with your instructions, I have held a formal investigation, under Section 83 of the Coal Mines Act, 1911, into the causes and circumstances of the accident which occurred at Stanrigg and Arbuckle Colliery, near Airdrie, on the 9th July last, by which 19 lives were lost, and I have the honour to report as follows :-

On the 15th August last I visited the colliery and made an inspection of the shaft which was sunk from the surface to the Humph Seam in connection with the operations to recover the bodies and also of the subsidence on the surface which was caused by the inrush of moss and water into the workings of that seam, and attended a meetings of the representatives of the owners and workmen as to the work of exploration for the purpose of the recovery of the bodies of the deceased men. On the 18th December I opened the Inquiry at the Sheriff Court, County Buildings, Airdrie, and on that and the following day heard the evidence of the following witnesses:-

1. George Johnston (Manager).
2. Matthew Penman (Miner).
3. James Sneddon (Drawer).
4. James Rafferty (Bottomer).
5. Robert Love (Miner).
6. James Dorman (Miner).
7. John Eadie (Miner).
8. John McCabe (Drawer).
9. Edward Quinn (Checkweigher at Ballochney Colliery).
10. William Love (Miner).
11. Alexander McComb (Miner).
12. James Bennett (Drawer).
13. John B. Wingate (Civil and Mining Engineer).
14. John Strang (Under-Manager at one of the United Collieries).
15. Ian Allan (Under-Manager at Darngavil Colliery).
16. James Pollock (Borer).
17. Edward McCracken (Fireman).
18. William McCracken (Fireman).
19. Thomas Shaw (Miner).
20. Thomas Marshall (Miner).
21. David McNiven (Miner).
22. David Mowat (Mining Engineer and General Manager of Summerlee Iron Co.).
23. Leslie McCracken (one of Owners).
24. James Brown (Miner).
25. William McIlvaney (Manager of Hillrigg Colliery).
26. James Crawford (Manager of Darngavil Colliery).
27. Robert Brown (Mining Agent and District Manager of United Collieries, Ltd., Westrigg and Cleland districts).
28. George Gibb (General Manager of collieries belonging to Messrs. James Nimmo & Co., Ltd.).
29. Robert W. Dron (Mining Engineer).
30. Thomas G. Thomson (Manager of Whiterigg Colliery).
31. John McCance (Manager of Barblues Colliery).
32. William Black (Manager of Ballochney Colliery).
33. Patrick McIlhenny (Sub-Inspector of Mines).
34. Arthur H. Steele (Junior Inspector of Mines).
35. Frederick H. Wynne (Senior Inspector of Mines).
36. Henry Walker (Division Inspector of Mines).
37. William McL. Kilpatrick (Mining Engineer).
38. Robert McLaren. M.P. (Consulting Mining Engineer).

Interests Represented at the Inquiry

The different interests, were represented as follows:-
Messrs. McCracken Bros., the Owners of Stanrigg Colliery, and the Manager, George Johnston: Mr. James Bell, Solicitor, Airdrie, and Mr. Robert McLaren, M.P. (Technical Adviser).

The relatives of the deceased workmen : Mr. G. Craig McIntyre of Messrs. Hay, Cassels & Frame, Writers, Hamilton.

The relatives of the deceased Bernard August McAdam: Mr. David Dickson, of Messrs. Thomas Scanlan & Co., Solicitors, Glasgow.

The Proprietors of the Minerals : Mr. James Mitchell, Solicitor, Coatbridge.

Scottish Mine Managers' Association: Messrs. James Black and William Stevenson.

The Miners' Federation of Great Britain: Messrs. W. Straker and W. Whiteley.

The Lanarkshire Miners' County Union: Messrs. James Murdoch and A. McAnulty, and as Technical Adviser, Mr. W. M. Kilpatrick.

There were also present Mr. H. Walker, H.M. Divisional Inspector of Mines, Mr. F. H. Wynne, H.M. Senior Inspector of Mines, Mr. A. H. Steele, H.M. Junior Inspector of Mines, and Mr. P. McIlhenny, H.M. Sub-Inspector of Mines.

The names, ages, and occupations of the victims of the disaster and those whose bodies have been recovered are given below : -

1. Description of Colliery
Stanrigg and Arbuckle Colliery is situated in the Parish of New Monkland, in the County of Lanark, about four miles east of the town of Airdrie. It is, and was on the 9th July, 1918, owned and worked by Messrs. L. arid A. McCracken, trading under the style of Messrs. McCracken Brothers.

There are three shafts:—No. 2 or upcast shaft, the downcast shaft, and No. 3 shaft, at which all material and coal was raised but which did not enter into any scheme of ventilation.

A blowing fan, driven by an electric motor and placed close to the top of the downcast shaft, caused 14,100 cubic feet of air per minute to circulate and ventilate the workings in the different seams.

Mr. George Johnston, holder of first-class certificate of competency number 4045, is and has been since July, 1915, the Manager of the mine. There were two firemen, William McCracken and Edward McCracken, aged respectively 24 on December 23rd 1918, and 28 years, both of whom were acting as firemen at the date of and prior to the passing of the Coal Mines. Act, 1911.

The colliery was worked by a single shift, that is to say, all work, both above and below ground, was done during one shift per day, the persons below ground being employed between the hours of 6.45 a.m. and 3.15 p.m. The firemen descended the No. 3 shaft each day about 6 a.m. and after making the inspections required by Section 64 (1) of the Coal Mines Act, 1911, to be made before the commencement of work in a shift, returned to the station, which was at the top of No. 3 shaft, and met the shift of men there. After passing the shift into the mine they returned below ground to continue their statutory duties. It was their custom to come to the surface about 10 a.m. to have their breakfast.

Three seams have been worked at the colliery viz., Humph, Splint and Virgin, which at the No. 3 shaft occur at the following depths from the surface:—Humph, 82 feet; Splint, 117 feet; and Virgin, 126 feet; but at the time of the accident the Humph and Virgin Seams (upper and lower leaf) only were being worked. The upper leaf of the latter seam was known locally as the "Sour Milk." The roads from the No. 3 shaft were in the Virgin Seam and two stone mines or drifts were driven from that seam to the Humph coal section.

The strata overlying the Humph Seam were proved by a series of boreholes, put down in October 1916, to consist of :-

Put down since the Accident on July 9th 1918

The seam had, up to the day of the accident, been worked without any of the moss and water being let into the workings. The method of working adopted in this seam was originally stoop and room, then long-wall with coal-cutting machines, but the latter method was finally abandoned owing to its being too costly and the stoop and room method was reverted to. There were, as will be seen on Plan No. 1, several faults in the seam, and one of these, an upthrow inbye of 1 foot, was close to the long-wall face when that method of working was stopped. This fault and the stopping of the long-wall face had, in my opinion, a very important bearing on the cause of the accident; this will be discussed later.

Narrative of the Accident
On the day of the accident the two firemen, as was their custom, came to the surface to have their breakfast between 10 and 10.30, and whilst they were at breakfast a bottomer at No. 3 shaft named James Rafferty came to the surface and informed them there was something wrong, as the ventilating current was "coming out very strong." They descended the No. 3 shaft at once, and William McCracken, who was fireman in the Humph Seam, was proceeding inbye when at about 90 yards from No. 3 shaft he met liquid moss moving along the haulage road in the Virgin Seam and pushing a hutch before it towards the shaft. Edward McCracken went to his section of the workings— the "Sour Milk" — and was able to proceed to the Wee Stone Mine leading to the machine section (see plan) before he met moss flowing towards him. He collected the men in that part of the workings and took them to No. 2 shaft, up which, after steam had been raised to work the winding engine there, they were drawn to the surface.

The inflow of the moss, by filling up the two roads by which the persons working in the Humph Seam could have escaped, had cut off and entombed 19 men and boys and prevented the rescue parties getting to them from the Virgin Seam. The 58 men and boys working in the other parts of the mine were rescued and got safely to the surface.

Senior Inspector, were engaged in the Sheriff Court at Kilmarnock, and at 12.20 p.m. they received a message by telephone from the Divisional Office in Edinburgh that a number of men were entombed in Stanrigg Colliery. They left Kilmarnock by the first train and arrived at the colliery between 4 and 4.30, when a description of what had occurred was given to them by one of the owners and the manager and they found that measures had been taken and were being made to reach the entombed men.

The operations were (1) the starting of a shaft about 5 feet square at a point considered to be immediately above the north-western edge of the workings in the Humph Seam, (2) the cleaning out of an old borehole which had been put down at some time before the accident occurred, and (3) the redding of a road from the No. 3 shaft through the old stoop and room workings, in the Humph Seam.

Much difficulty was encountered in the endeavour to clear out the old borehole, and as the borer considered he could put down a new hole more quickly, one was started; the attempt to sink the 5 feet square shaft was continued, as were also the redding operations below ground.

It was found that to sink through the moss something of the nature of a boiler shell was required and steps were taken to obtain such a shell of suitable size. The first length of boiler shell, which, after much difficulty, was obtained, was on the ground at 10.30 p.m., and the second length sometime later.

In the meantime, the attempt to put down a new borehole had failed, owing to the breakage of the lining tubes, due to the movement of the moss, and a second attempt also failed from the same cause about midnight. The first attempt failed when the borehole had reached a depth of 44 feet and the second 48 feet. At the sites of these boreholes the Humph Seam, was about 60 feet from the surface.

Prior to the arrival of the boiler tube a survey was made and the position of a new sinking marked off, as well as the situation of further boreholes, and two boreholes were started subsequent to the failure of those already mentioned. By 11 a.m. on the 10th July the boiler shell was down 22 feet and into the clay and plumb. The liquid material within it was cleared out during the afternoon but, owing to the movement of the general body of the moss, it was impossible to keep the shell plumb and the further sinking within it had to be abandoned. One of the boreholes, however, reached the pavement of the Humph Seam and in it water was measured to a depth of 16 1/2 feet above the pavement of that seam. From this it was apparent that the face at the highest level in the workings was under water but, in order to be sure, another borehole was started within the boiler shell within which the sinking operations had been abandoned. This borehole could not be got down owing to the lateral movement of the moss bending the lining tubes and another was then started at a point about 12 to 15 feet further to the east. This hole reached the pavement of the Humph Seam between 6 and 7 p.m.. on Thursday, 11th July, and proved the water to be at that point 8 feet 9 inches deep above the pavement. This was the highest point of the workings in the Humph Seam in which the 19 men and boys were, and any hopes of their being found alive were extinguished.

The redding of the road through the old stoop and room workings from No. 3 shaft was continued by relays of men. The distance to be redded, measured in a straight line, was 462 feet before the nearest recent working could be reached. Connected with this redding of this road there was a risk of the means of the egress to the surface of the men engaged in the redding being blocked by an inrush of moss up No. 3 pit and up a blind pit which had formed the intake airway from the Humph to the Splint Seam, but it was continued until the borehole above mentioned reached the Humph Seam and proved water to a depth of 16 1/2 feet, and that the entombed men could not be rescued alive. As a matter of fact, the moss rose in No. 3 shaft to within 32 feet of the surface.

The hope of rescuing any of the nineteen persons below ground having to be abandoned, the question of the recovery of the bodies arose and it was decided to sink a shaft on the site of the borehole which had proved the level of the water to be 16 1/2 feet above the pavement of the Humph Seam. After considerable delay a shaft was sunk to the Humph Seam and the roads in that seam to the top of the stone drift or mine driven from the Virgin Seam were cleared of moss. Three barricades were then erected at such points as isolated the area in which the inrush had taken place, and thereafter the work of clearing the roads was carried out from No. 3 shaft.

Eight bodies were recovered in the roads cleared and it was expected the remainder, except that of the brakesman, whose working place was at the top of the mine leading from the Virgin up to the Humph Seam, would be within the area which had been shut off by the three barricades referred to above. One of these barricades was removed and the roads immediately on the inbye side were explored as far as it could be done without undue risk, but, although the face was reached in three places, no bodies were found.

The operations on the inbye side of the removed barricade, owing to the finding of a break in the roof about 3 1/2 feet wide by 13 1/2 feet high, measured from the pavement and, so far as it was cleared lengthwise, 6 feet long, coupled with the distance from the means of egress, caused further operations to be attended with serious risk to the workers and they were very properly withdrawn and the barricade, which had been removed, was replaced and the roads between the workings and the No. 2 shaft and Nos. 2 and 3 shafts were then cleared but no more bodies were recovered.

The bodies of the eleven persons who were not recovered are most probably within the area which was barricaded off, and it was impossible to make further attempts to recover them without incurring a serious danger of causing a further inrush of moss, which would probably have overwhelmed the explorers and caused a further loss of life. This view was concurred in by all concerned.

All the witnesses at the Inquiry were of opinion that the entombed men could not have survived more than two hours from the time the moss broke into the workings. This was the longest time any witness thought there was any hope of anyone being alive - the others were of opinion that from half an hour to an hour was the more likely time and, after careful consideration, I have arrived at the conclusion that they could not have survived the accident more than half an hour.

For this reason there is no doubt that the delays which occurred in the work of rescue cannot have had any influence whatever upon the number of casualties. That there was considerable delay in the operations to reach the entombed men was generally admitted, and that the delay could have been avoided was also apparent and, therefore, to be regretted.

The delays were due to the lack of necessary material and equipment to sink a shaft or put down bore holes, and the difficulty, owing to the Glasgow Fair Holidays following immediately after the accident occurred, in being able to obtain them, and to a reluctance on the part of the owners and their expert advisers, after it had been shown by boreholes that no one would be alive, to incur any cost in any operations which would not be of use in the future working of the colliery. In any case, as stated above, it is quite certain that the delay which occurred had no influence on the number of lives lost or on the number of bodies which have not been recovered.

Practically all the witnesses agreed that the roof of the Humph Seam at this colliery was good, and it is probable that on this account too little attention was paid to the warnings given by the falls of roof which occurred a short time prior to the accident.

The sections of strata revealed by the borings showed considerable variations at comparatively short distances apart, not only as regards the depth of the moss, but more particularly as regards the thickness of the intervening strata above the Humph Seam.

Generally, the thickness of the moss is about thirty feet over the area (approximately 5 1/2 acres) in which the subsidence occurred and immediately below it there is a thickness of blue clay and stones varying from five to twenty-two feet, while between that and the Humph coal are strata from eight to twenty-nine feet in thickness.

This latter section was the only one on which any great reliance could be placed as a support of the moss, and the necessary " brushing " in the roadways reduced its thickness further by about three feet.

The boreholes put down before and after the inrush occurred indicate a certain thinning of the till below the moss in the neighbourhood of the "sit," and it is evident that, where the falls occurred near Pollok's platform and in Williamson's place, if they did not actually go right up to the blue clay, they approached it so nearly that there was little reliable support left for the weight of moss above.

There were three separate falls reported to the manager on the inside of Pollok's platform, the first occurring just inside the platform and the second some eight feet further inbye, while the third took place at the point where the 1-foot upthrow fault crossed the road.

The evidence concerning the extent of these falls was somewhat conflicting, but it is apparent that in the case of the third fall at the fault certainly not more than 3 feet thickness of metal and probably less was left beneath the clay. Some significance may be attached to the fact that after this third fall had been repaired the manager gave instructions for the road to be stowed up, but he stated that his reason for doing this was on account of the road approaching another fault of 5 feet. The fact, however, remains that these falls should have indicated danger, especially in the neighbourhood of faults, and special precautions should, I think, have been taken to meet it.

The repairs made after these falls had occurred were not carried out with any consideration of danger from the moss, and no special precautions appear to have been taken, whereas it would have been good practice to have built up the falls either with brick arching or steel girders, so as to prevent movement in the strata as much as possible. More particularly should this have been done in the case of the third fall near the 1-foot fault.

The method of working first employed in the Humph Seam was stoop-and-room, but in April, 1918, a coal-cutting machine was started on a longwall face. This worked until June 22nd, when it was abandoned on account of the excessive cost, and the stoop-and-room method of working was again introduced.

Owing to the natural subsidence of the strata over the longwall workings, as soon as the stoop-and-room method was commenced, a break-off would necessarily occur in the roof over the longwall waste, and the fracture would probably go up at an angle of about 45° until it met the listing of the 1-foot fault referred to, when a triangular piece would be formed probably reaching up to the blue clay. The weakest point would be, of course, the roadway, and all the more, because of the recent, falls that had taken place there, and this was, in point of fact, the place where the inrush of moss occurred.

There was some diversity of opinion as to whether it was advisable to have worked this, seam by the longwall or the stoop-and-room method, but it was generally agreed that it was a dangerous practice to change from one to the other and then to revert back to the first method employed—the stoop-and-room - and whichever method had been adopted at the outset it would have been better to have continued.

Most of the expert witnesses at the Inquiry came to the conclusion that it was desirable, in circumstances such as appertained to this colliery, to leave some 30 to 40 per cent, of the coal in as a support, and to carry this out it follows that the longwall method of working should not have been employed at all.

The boreholes put down prior to the accident were for the purpose of proving the Humph Seam, and not to determine the depth of the moss or thickness of strata between the moss and the coal, though they, of course, showed this. Several of the expert witnesses at the Inquiry expressed the view that it would be desirable for some systematic soundings of the moss to be taken which could be plotted on a plan to the ordnance datum, and which, when considered in relation to levels taken in the workings, would show the amount of strata to be depended upon. Such soundings could have been made either by boreholes from the surface or from the seam; and, had they been taken, any thinning out of the clay would have been shown, as also would the intervening strata to be depended upon as support for the moss, and this accident prevented. All were agreed in order to make certain that the necessary precautions, to prevent accidents in similar circumstances are in future taken, that where there are workings under moss, quicksand or other liquid matter within 50 feet or less of such moss, quicksand, &c., a regulation should be established requiring the owner or manager to give notice to the Home Office and thereafter the precautions to be taken should be considered by a Committee consisting of representatives of the Inspectors, the owners and management, and workmen, and such precautions as this Committee decide are necessary for safe working should be adopted. This, in my opinion, is a wise and necessary course to take. The conditions in each case vary so much that it is not possible by regulation to lay down the precautions, necessary at each individual mine or part of a mine.

Valuable evidence as to the precautions taken by them when working under moss, and those which are, in their opinion, necessary to provide for safety in future, was given at the Inquiry by Mr. D. M. Mowat, Mining Engineer and General Manager of the Summerlee Iron Co., Ltd., Mr. George Gibb, General Manager of the collieries belonging to Messrs. James Nimmo & Co., Ltd., Mr. Robert W. Dron, Mining Engineer, of Glasgow, Mr. James Crawford, Manager of Darngavil Collieries, and Mr. Robert Brown, Mining Agent and District Manager of the collieries belonging to the United Collieries, Ltd., in the Cleland and Westrigg districts.

These gentlemen have had a wide and varied experience of working mines under all conditions, and the majority of them in circumstances similar to those which existed at Stanrigg and Arbuckle Colliery. They are, it will be seen, generally agreed as to the nature of the precautions which are necessary in such circumstances for safe working and in particular as to the necessity of establishing a regulation requiring steps to be taken to ascertain before working seams under moss, quicksand or other liquid matter, the conditions existing, and if the strata between the seam and the moss, quicksand, &c., is found to be less than a prescribed distance, that notice should be given to the Home Office and thereafter the question of what precautions are to be taken to be considered by a Committee consisting of the Divisional Inspector of Mines and representatives of the owners and workmen.

For the information of the management of, and persons employed, in mines working under conditions similar to those existing at this colliery, I give excerpts of the evidence of the witnesses in question in Appendix 1 to this report and would urge careful perusal thereof.

Conclusions
1. There were no contraventions of the Coal Mines Act, 191.1, or of the General Regulations in connection with the accident.

2. There was considerable avoidable delay in the work of exploration after it had been ascertained by boreholes that the whole of the area in which the deceased men were entombed was under water, but such delay did not cause any loss of life or prevent the recovery of any of the bodies which have not been recovered.

3. The accident was caused by an inrush of moss into the Humph Seam due to (1) the small thickness of strata between that seam and the bottom of the moss; (2) the nature of that cover; (3) a probable thinning of the blue clay underlying the moss; (4) the presence of faults near to the line of the long-wall face when it was stopped; and (5) the stoop-and-room method of working by which the seam was extracted when it was first opened having been changed.

4. The manager in changing the system of working committed an error of judgment. In the conditions which existed, I am of opinion a great risk of causing a sudden inrush of moss was run even if the blue clay had not thinned by the change from one system of working to another. Either of the two systems (longwall or stoop-and-room) throughout would have been less dangerous than to start with one and then afterwards change it.

5. In the circumstances which existed the safest method of working to adopt and adhere to was the stoop-and-room, with rooms of a maximum width of 8 feet and stoops left for support of the clay of such a size that not more than 50 per cent, of coal was extracted.

6. The conditions vary so much as regards the thickness of the clay, depth of moss, &c. from mine to mine, and even in the same mine, that it is not possible to have a Regulation dealing with the precautions necessary for safe working applicable to all circumstances, and I think, therefore, for the prevention of similar accidents in future, a regulation should be established requiring that where coal or other mineral is being worked or roads driven under moss, quicksand, or other liquid matter, (a) steps shall be taken by boring or otherwise to ascertain, as accurately as possible, the nature and thickness of the moss, quicksand, &c., and of the strata between such moss, quicksand, &c., and the working or workings. (b) Where the thickness of the strata between the working or workings and the moss, quicksand, &c, is proved to be less than 10 fathoms, or ten times the thickness of the seam being, or proposed to be, worked, whichever is the greater, all working to be stopped and notice given forthwith to the Inspector of Mines of the Division.

The question of whether any further working is to be allowed, or, if allowed, the precautions to be taken, to be referred to a Committee of the Inspector of Mines of the Division (Chairman), one representative of the owners and management and one representative of the workmen, and if the Committee are of opinion that precautions are necessary, the working of the seam shall, subject to the approval of the Secretary of State, only be continued on condition that the precautions recommended by the Committee are adopted and earned out.

If any question is raised subsequently by an Inspector of Mines the owners and management or persons employed, as to the efficacy or otherwise of the precautions, it should be referred to a Committee constituted as above and, subject to the approval of the Secretary of State, the precautions amended1 or varied as the Committee may suggest.

In the event of the Committee being unable to agree the matter should be referred in the same manner as provided by the Coal Mines Act for settling disputes.

Attached to this report are a plan showing the workings and the area of the subsidence on the surface caused by the inrush, and two sections showing the seams and faults in relation to the moss and surface, and also an appendix giving extracts from the evidence of expert witnesses as to the precautions which have been taken when working under moss at other collieries, and those which, in their opinion, should be taken in similar circumstances, such as were present at this colliery, to prevent accidents in future.

I desire to place on record my indebtedness to Mr. A. D. Lindsay, the Procurator-Fiscal at Airdrie, the representatives of the various interests who appeared at the Inquiry, and to Mr. H Walker, H.M. Divisional Inspector of Mines, and the other Inspectors, for the very great assistance they gave me in connection with the investigation of the accident and the Inquiry.

I have the honour to be, Sir,
Your obedient Servant,
W Walker
The Right Honourable the Secretary of State,
Home Office,
Whitehall, S.W.I.

Links to Figures & Plans:

Figure 1            Figure 2           Figure 3

Extract from Evidence by Mr. David M. Mowat, Mining Engineer and General Manager of Summerlee Iron Co.
I am a mining engineer, and General Manager of the Summerlee Iron Co., Ltd. I am President of the Mining Institute of Scotland and a Vice-President of the Institution of Mining Engineers. I am also a local examiner in connection with the granting of certificates of competency to colliery managers, under-managers and surveyors.

I have had over 40 years' experience of working coal, ironstone and fireclay in Scotland, and in connection with the recent disaster at Stanrigg Colliery, I have considered what steps might be taken to prevent a recurrence of such an accident. I have no particular knowledge of what took place at Stanrigg, and my remarks are intended to be of general application.

It is generally believed that seams of stratified material including coal, ironstone, fireclay and shale have been deposited originally in a more or less horizontal position. This is supported by the fact that they are found in the form of layers more or less regular in thickness and lying more or less parallel to each other. These seams, however, have not been permitted to remain as they were deposited, but have been tilted up by earth movements until, now, they are found lying at all angles from the vertical to the horizontal.

These earth movements, besides tilting up the strata, inclined the surface of the earth and the agencies of water and frost over long ages materially altered the shape of the earth's surface. Water and ice moving downwards from the higher levels to the lower, wore away the higher parts and deposited the debris in the lower parts in valleys, lakes and seas. As a consequence of this tilting up and denudation, the ends or outcrops of many seams became exposed at the surface.

It is generally near these outcrops that danger of accident such as occurred at Stanrigg is to be apprehended. In the vast majority of cases, no danger is to be feared in working a seam right up to the outcrop, as the seam impinges against clay or other material. Where the outcrop is overlain by wet moss or quicksand or like material, special precautions should be taken to avoid or remove the source of danger. These deposits of moss or quicksand are usually found in valleys hollowed out by rivers or by ice. When a river is found flowing over a rocky bed, there is no danger, because there is no difficulty in determining the exact distance from the seam being worked to the hard river bed.

When a river flows slowly through a broad, flat valley, the bed often consists of gravel and sand, and these may be present to a very considerable depth. The river bed, at some time or another, may have been at a much lower level, and by an earth movement, it may have silted up, so that there may be a deposit to a depth of hundreds of feet of sand and gravel below the apparently firm surface of the meadows alongside the river. Or, the river course may have been entirely changed and no trace left on the surface of the land to give any indication that such a quicksand may exist.

A lake presents another problem. It is necessary to ascertain the position of the bed of the lake by sounding, in order to determine its distance from the seam which is being worked.

A shallow lake or a flat valley may become filled with moss to such an extent that the configuration of the lake or valley entirely disappears.

In all these cases, it becomes necessary, before working seams in proximity to such surroundings, to ascertain in some way or another when danger may be anticipated. The conditions existing are so varied that it is impossible to prescribe any uniform method, of ascertainment. Generally speaking, it can best be done by boring, either from the surface or from' the seam. This is the first thing to be done. Afterwards, when it has been ascertained where the bottom of the moss or quicksand is, it is comparatively easy to decide how the workings must be kept back from such moss or quicksand, or how these dangers may be rendered innocuous.

In order to discover where the stable surface exists, it is usually necessary to put down a line of bores across the valley or depression. The distance between these bores and lines of bores will entirely depend on the nature of the irregularities they disclose. Where they show a slow and gradual descent to the lowest point, with a corresponding slow and gradual ascent on the other side, the bores and lines of bores may be widely separated. Whereas, on the other hand, if the stable surface is found to vary abruptly, bores must be put down at shorter intervals, as the object must always be to obtain an accurate idea of the contour of the stable surface underlying the danger. It is the want of such knowledge which constitutes the real danger.

Extract from Evidence by Mr. George Gibb, General Mining Manager for Messrs. J. Nimmo & Co., Ltd.

I have had over 30 years' experience in coal mining, and at present act as General Mining Manager for Messrs. James Nimmo & Co., Ltd., who have a number of collieries in the Longriggend District, a few miles east of Stanrigg, where the disaster occurred.

The leasehold at Longriggend has been worked continuously for the past 50 years, a large area being under moss lands.

The method we adopt in working under the moss consists roughly of leaving unworked all coal above what we consider the safe working level. This level is determined by a series of shallow bores distributed over the whole area of moss and put down to get thickness of moss, clay and stratified rocks and sometimes to prove the position of the coal. Careful levellings of these are taken and the surveys and levels of our underground work carried forward regularly, so that we know exactly the depth and nature of the overlying strata, clay and moss.

The boulder clay we find fairly regular, generally from 9 to 12 ft. in thickness. Our general practice is to leave the coal intact for a distance measuring from the top of the stratified rock's, equal to the depth from the surface of the moss to the bottom of the boulder clay. In approaching the surface line where the moss gets thin and the clay forms the overlying ground, we sometimes come nearer to the surface than indicated by the safety line. A system of drainage can usually be adopted which lessens a the danger and admits of greater liberty being taken. This rule has so far proved safe, and we have not had a case of a break-in of moss.

Particular care must be observed when operating in the vicinity of faults near the safety line. Our practice in such instances is to leave the fault unstripped.

Our seams are thin, running about 15 in. to 24 in., and, consequently, well packed with resultant small subsidence."

Extract from Evidence by Mr. R. W. Dron, Mining Engineer.
I have been engaged in coal mining in Scotland for the last 30 years, and am acquainted with all the coalfields.

In the course of my experience, I have frequently had to deal with the surface deposits overlying the coal seams, but I have not been connected personally with any case where moss or peat has broken into coal workings.

I have, however, studied the surface deposits from a geological and mining point of view.

If the danger due to the presence of moss and of running sand is to be guarded against, some knowledge of the conditions under which these materials were deposited is necessary.

The important fact regarding the nature of the surface overlying the Scottish coalfields is that at a comparatively recent period the whole area was covered with a thick mass of ice.

The time when this occurred is known as the glacial period.

Immediately before the glacial period, the surface of Scotland appears to have been an ordinary land surface, with large rivers flowing across the country.

When the ice came, the channels of these rivers became filled up, and, subsequently, the whole area was covered with a deposit of glacial debris. This debris consists frequently of sand and gravel, but the greater part of it is stiff, plastic clay mixed with stones and boulders, and known as boulder clay. The sand and gravel form irregular deposits, mostly laid down as glacial moraines. The boulder clay appears to have been laid down under the ice. It extends in a sheet over most of the lowlands. As the glaziers melted away, the boulder clay was traversed by streams of water.

We thus find that at places the whole of the boulder clay has been washed away, and sand and gravel is lying on the adjacent strata. The retreating ice must have left the surface with very irregular contours with numerous depressions which would be filled with water.

Some of these sheets of water remain to the present day. A typical instance is the series of lochs stretching from Hogganfield, near Glasgow, to Woodend Loch, near Coatbridge.

In other cases the hollows in the boulder clay have become filled up with vegetation. These hollows form the peat mosses. Typical peat mosses are found more or less continuously throughout an area extending from Robroyston, near Glasgow, eastwards by Airdrie and Slamannan to Polmont, and Shotts.

So far as I am aware, no consistent theory can be propounded whereby the depths of these peat mosses and their relation to the boulder clay on which they rest can be established. The areas and depths appear to be quite irregular, and depend entirely on the varying conditions which were present while the ice was melting.

As a general rule, the moss is resting on the boulder clay, but at any point this boulder clay may have been washed away or ended before the moss was formed.

In districts where soft, undrained moss is found, the only safe rule is to assume, until it has been proven to the contrary, that the underlying boulder clay may have been washed away.

In these areas the depth of the moss .should be proven, just as the depth of water would be proven if the workings were coming underneath a loch.

The fact that the surface is covered with growing heather gives a deceptive appearance of security.

These remarks only apply to areas where the moss has not been drained to the bottom.
From the foregoing observations on the irregular nature of the boulder clay, it is obvious that a considerable number of bores would be required in a given area before one could have any sure knowledge regarding the contour of the basin in which the moss has been deposited.

In view of the accident at Stanrigg, I think some regulation should be made for the guidance of those who are conducting operations underneath undrained mosses. I would propose the following:-

In the event of coal or other minerals being worked underneath a deposit of peat moss or other soft material containing water, intimation shall be given to the Mines Inspector before such working approaches nearer to the bottom of the peat or moss than 50 ft., or 10 times the thickness of the seam which is being worked, whichever is greater. The system of working above the 50 ft. limit should be determined after consultation with experts, and for this purpose the proposed Ministry of Mines might form an Advisory Committee with local knowledge.

Extract from Evidence by Mr. J. Crawford, Manager, Darngavil Colliery, Airdrie.

I have been Colliery Manager with Darngavil Coal Co., Ltd., for the last 18 years, first five of which at their West Longrigg Collieries, Longriggend, and the latter 13 years at Darngavil Collieries, Rawyards, Airdrie. Previous to this, I was one year at Barblues Plains, with A. & G. Anderson, and four years with the Caledonian Oil Co., at Tarbrax, being employed as under-manager at both these places. With the exception of Barblues Plains, at all these places we were working under moss cover varying in thickness from 0 up to 60 ft. and the clay from 5 to 15 ft.

Tarbrax.- In the year 1894 I was employed by Mr. John Allan, Mining Manager to the Caledonian Oil Company, to be under-manager in their No. 2 Pit. In this pit the Fells Shale was being worked by the stoop and room system. The height of the working was 5 to 5 1/2 ft., the rooms 12 to 15 ft. wide, and the stoops removed beginning at the boundary and working back towards the shaft. At the nearest point the thickness of the metals between the moss and the seam was not less than 130 ft. and most of the working area double that thickness. In this case the moss varied from 0 up to 30 ft. in thickness, but, with these conditions, no extra precautions were necessary. Some time, I think, in the year 1905 we began to sink a small shaft on the Viewfield Estate to the Hurlet Coal. The shaft, if I remember right, was somewhere about 7 ft. by 6 ft., and was sunk with piles through the moss, which was 60 ft. thick. The coal was got at a depth of about 22 fathoms or thereby, varying from 3 ft. to 3 ft. 6 in. thick, and at an inclination of 1 in 6. A line of longwall faces about 700 ft. long was set away to the rise advancing direct towards the outcrop of the seam. The working section of this seam would average about 4 ft. high, so that, with these conditions, you will readily see that this was a case for the very greatest care and closest supervision. Mr. Allan was a man of exceptional caution and experience, and it was under his supervision that I was employed here from time to time, where I got what will probably prove to be my greatest experience of working coal under moss cover.

Precautions. - The precautions in this case were a careful system of surveying, levelling and boring. The levels were taken frequently to ascertain the thickness of the metals at different parts of the workings, also to fix approximately the line of the outcrop of the seam. A number of bores were put down along this line to fix as correctly as possible the outcrop of the seam. From this fixed line of outcrop another line was pegged off on the surface, beyond which the line of face was not to advance. I am not in a position to say definitely what distance this line was back from the outcrop, but from an old tracing that I have of the last survey of these rise workings, I calculate this line to have been back from the line of outcrop about 132 ft. or thereby. There were, at least, two bores put down on this line to prove the nature and thickness of the metals, but it is so long since, that I have not the slightest remembrance of what the results were. In addition to these arrangements, the roof in these places going to the rise was well supported by pillars of both stone and wood throughout.

West Longrigg Colliery. - At this colliery the depth of moss varied from 0 in some parts of the field up to 30 ft. in other parts, but since before my time nothing had been worked here nearer to the surface than 30 fathoms. The circumstances in this case did not require the necessary precautions. The seams worked were Upper and Lower Drumgray, and thickness varying from 16 in. to 24 in., and the system of working long wall.

Darngavil No. 6 Pit, Humph Seam. - In this pit we worked about four acres of Humph coal at a depth of 41 ft. from the surface, and in this small area at no point was the moss thicker than 5 to 6 ft. and when the excavations for the foundations were made was found to be in a solid condition. As the working advanced towards the west, the metals thinned off, -leaving the boulder clay for a roof. The seam varied from 23 in. to 33 in. thick and was worked by long wall. The boulder clay was 24 ft. thick. This area was exhausted some time ago.

Darngavil No. 6 Pit, Virgin Seam. - In the present working area of this seam the total cover is 98 ft. and the depth of moss 12 ft. to 14 ft., with an under clay from 10 ft. to 14 ft. thick. The metals are of the usual nature, consisting of blaes with frequent ribs of ironstone, also fakes and sandstone containing ribs (extra hard). The system of working is by long wall, and the height of the working 3 ft. The roads are well built and the waste filled with the stone obtained from the working of the seam. This seam has been cut by a mine at a higher level where the cover has been proved to be 11 fathoms 2 ft. No development has been done yet at this level, the area of which is about 10 acres. This small area has been proved by seven bores, four of which went down to the coal, the other three were stopped at the bottom of the clay. No. 3 bore shows a cover of 50 ft., consisting of fakes, fireclay, blaes and sandstone. The depth of the moss being 18 ft. 6 in., I have drained all previous site and cleared all old existing surface drain, so as to run the water from the moss as it falls and prevent it from accumulating on the top of the clay underlying the moss. This, at least, will help to prevent the moss from getting into a liquid state and considerably reduce the risks of mining under the moss.

No. 6 Pit, Musselband Coal. - This seam is being worked in this pit at a depth of 22 fathoms from the surface. The method of working is long wall, and the thickness of the seam 2 ft. and the height of the working 3 ft. The moss in this area is 12 ft. to 14 ft. thick.
All my experience has been entirely free of accidents from moss breaking in.

Stanrigg Colliery.
In view of what has occurred at Stanrigg Colliery, I beg to submit the following suggestions, which, in my opinion, would safeguard the lives of those employed mining under moss cover where the intervening strata were thin: —
Surface Precautions.
1. A proper system of shallow surface drains to run off the water as it falls and prevent it accumulating on the top of the underlying clay until the whole moss is in a liquid condition.
2. All old sits or subsidence to be drained dry.
3. A careful system of boring, so that the various thicknesses of moss and metals are known. '
4. Where any doubt still exists as to the condition of the moss, a small shaft or hole might be put down throughout the moss to the clay.

Underground Precautions.
1. Drawing roads to be no wider than necessary and to be well secured with timber at all branches or junctions, also where necessary along the roads.
2. Waste to be properly packed throughout, supporting the roof.
3. All hitches and dislocations of metals to be carefully noted and the roof at such parts secured by a proper system of pillaring.

With these precautions carefully attended to, I am quite confident that it. would be perfectly safe to work a seam by long wall up to a working height of three feet where the depth of metals were equal to the depths of moss.

Extract of Evidence by Mr. Robert Brown, Mining Agent and District Manager for United Collieries, Ltd.
My first experience of dealing with colliery accidents through the inflow of moss was the Moss Morran accident in Fifeshire in the year 1901, when eight lives were lost.

This accident was the result of an attempt to sink an air-shaft from the outcrop of the Mynheer Seam to the surface a distance of about 40 ft.

The strata there, from the outcrop of the coal, were sand and moss; a section of this moss immediately overlying the sand was of a hard, stiff nature, to which, I have no doubt, may be ascribed the immunity from accident during the 10 months this particular heading was standing. The whole of the coal having been worked out to the outcrop at that time.

Prior to this, little thought was given to .the dangerous nature of working coal seams at shallow depths under moss, and it was not until the wide publicity of this disaster that the attention of mine managers generally was drawn to this danger.

Being present during practically the, whole; period that .rescue operations were being carried on, the risk of accidents in work of this nature was strongly impressed on my mind, and on coming to this district, where considerable areas of coal were being worked under moss, I set about collecting all the information possible regarding the depth of coal seams from the surface, also the depth of moss and nature of strata, underlying the moss; and from this I found that as regards the seams of coal presently being worked, there was a considerable margin of safety.

I also learned that, on at least two occasions there had been inflows of moss into the workings of East Benhar Colliery, Linlithgowshire, and on the second occasion with fatal results. One man lost his life, and, although a rescue pit was sunk and search made, the body was never recovered.

The seam of coal was 4 ft. in thickness, and the depth from the surface 9 fathoms, 22 ft. of this being moss.

When the second inflow o£ moss occurred, I understand the miners were engaged in working out the pillars of coal which had been left in during the first working, the seam of coal bei»ng worked on the stoop and room system.

A borehole was put down on the the dip side of the workings where this inflow took place, and it showed 9 ft. of moss and 1 ft. of clay underlying the moss. The remainder of the metals to the coal seam—l2 fathoms in depth , here —were fairly good, showing the variations of moss in thickness.

The information gained from nearly 100 boreholes which had been previously put down through the moss, to the coal seam, and also from a number put down under my own supervision, have proved, without any doubt, that one could not rely on a certain depth of moss, with a certain depth of clay underlying the moss, continuing, for any distance.

The variations in the depth of moss and in the nature of the strata immediately underlying the moss are most marked. Underlying the moss, we have sometimes clay, more often the moss is lying on a bed of sand and gravel, and in a few of the boreholes the moss is found lying on a bed of loose sand.

In trying to estimate the degree of danger when working in a shallow seam of coal under moss, in my opinion, it would not only be necessary to know the depth of the moss, but also to know the nature of the material underlying the moss. If this were found to be sand and gravel, the degree of danger is increased to the combined depth of the moss, sand and gravel; and, as these are most variable in thickness even at a short distance apart, it follows that where shallow seams are worked under moss, a regular system of putting down boreholes should be inaugurated.

From, the knowledge of the Moss Morran disaster, and the accident I have referred to at East Benhar Colliery, I would have said that a 3 ft. seam of coal working at a depth of 10 fathoms from the. surface—25 to 30 ft. of this being moss—was quite workable with safety, either by long wall or by stoop and room method.

It is now apparent that working a 3 ft. seam of coal, as at Stanrigg, by long wall will not be safe, and even, the stoop and room method could not be safely adopted, unless the depth of moss and strata under the moss are known.

Great care should also be exercised in deciding on the width of the working places and the size of the stoops of coa to be left in, and in no case, as under the conditions prevailing at Stanrigg Colliery, would it be safe to work out the stoops as a second working.