pronounced in degree. In Scotland the grievances of the Local Authorities were more prominently elaborated than were those of the householders. There too, however, we noticed in the larger towns the tendency, now happily decreasing, to build houses, frequently of three or four storeys, in long terraces instead of in small blocks.

39. As to the works of Local Authorities, both in Wales and Scotland, we were not convinced that these had in all cases been constructed with due foresight. In saying this we do not forget that in the case of certain works, e.g., reservoirs and sewage works, the choice of site is necessarily limited. Take the case, however, of water-mains-a frequent subject of complaint. Greater unification among the authorities concerned would, we think, in many cases decrease the subsidence damage to them. In the Upper Ward of Lanarkshire, for instance, no fewer than five different Authorities draw their water supply from the same area by five different sets of pipes, in some cases coming down the same road.* We are given to understand too that in the case of gas mains the use of mild steel instead of cast iron would reduce the loss of gas caused by breakages due to subsidence t and that in the case of sewers and other mains cast iron or steel pipes are preferable to brickwork since the risk of breakage is less and it is often practicable to raise such pipes as a whole after subsidence. We should like here to put on record an interesting device which we saw during our tour of the Rhondda Valley. There a trunk sewer is laid on piers in the river bed, and whenever a portion of the sewer subsides it is restored to its old level by raising the piers which are, of course, readily accessible. As to school buildings, to take another example, while the buildings must for necessary convenience be located in the main centres of population and suitable sites free from risk of subsidence are frequently not available, we were struck by the fact that in cases where the risk must have been serious little care had been taken to avoid unnecessarily heavy and ornate structures. In at least one of the damaged schools we inspected this was notably so. In another case several times referred to in the evidence§ the elaborateness of structure of a school, subsequently completely wrecked, was due solely to the influence of local patriotism which was proof against expert advice.

40. In the result the impression produced upon our minds by our visits both to Wales and Scotland was that, in the aggregate, even assuming all the damage we saw to be damage for which there was no redress, it was less both in degree and extent than we had been led to expect; that much of it would in future be preventable, and that some of it ought perhaps to *Whyte-Q. 3513.

† Per contra, however, the life of steel pipes buried in the ground is, we believe, shorter than that of cast iron pipes under similar conditions. Gibbon (29)-3rd Day, p. 53. Also, Q. 836.

Gibbon (15)-3rd Day, p. 51.

have been avoided. But, even so, instances of great individual hardship were brought to our notice, for which we would be glad to find some measure of relief, if at all possible.

As to damage to future buildings, the problem in South Wales, so far at all events as the workers are concerned, is now less formidable, because the area is already fully developed. We saw there, moreover, enough to satisfy us that such damage can be substantially lessened by a more careful lay-out of buildings than has hitherto been practised as well as by special methods of construction to be adopted where some subsidence of the foundations is sooner or later almost inevitable.

Surface Without Right of Support or Compensation.

41. We are free now to discuss the question how far the practice has gone of inserting in instruments of severance conditions entirely destructive of the surface owner's rights to redress in this matter. Here we are led to the conclusion that the practice, while undoubtedly not uncommon, is by no means universal-it is indeed still, taking the country as a whole, the exception rather than the rule, and we should hope that with the passing of time and as a result of the Mines (Working Facilities and Support) Act, 1923, it may gradually become obsolete, so that a right to compensation, appropriately conditioned in each particular case, will come to be recognised as the normally fair arrangement between surface and mineral worker, and that compensation so conditioned will come to be judicially accepted as normally a proper substitute for support.

42. Striking as was the evidence of the growth of the practice in recent years particularly in the Welsh coalfield-the evidence that it had not become universal or even very common was equally cogent. Indeed, that evidence leads us to the conclusion, which we express with a feeling of reasonable certainty, that, taking the country as a whole, industrial dwellings are in the vast majority of instances not inadequately protected in this regard. There is, for example, little trouble on the great estates of the Ecclesiastical Commissioners, and Mr. Forster-Brownt-speaking as he was of the Welsh coalfieldtold us that as a result of an examination made by him of 530 mining leases in his office the mineral lessee was in 500 instances liable for all surface damage and in 26 for all damage to buildings existing at the date of the lease.

The late Mr. Parker Rhodes, too, gave 80 per cent. as the proportion of mining leases passing through the hands of his firm (mainly Yorkshire leases) in which the lessees are liable for surface damage.

43. But if a serious evil does exist, even to a limited extent, we are not dispensed by these comfortable figures from finding a remedy for it, if we can. The hardship to a poor man whose house falls without recourse for his loss is not to him less. serious because his misfortune is singular. The fact, however, that the mischief is restricted in character must call for care that there is not suggested a remedy which, being of a general application, may be worse than the very limited disease it is designed to cure.

Methods of Mitigating Subsidence Damage.

44. It becomes important, therefore, to ascertain how far the consequences of subsidence can be neutralized or modified. If effective steps to that end can be taken, it may well be that the expense, not being of course prohibitive, ought to be incurred whether it has to be borne by the mineral worker or the surface owner. Prevention here is always better than cure. When the mineral worker is liable to make compensation, such precautions as may properly be taken by him might reduce his liability to vanishing point. So far as the surface owner is concerned, the result of such precautions, by whomsoever taken, would be far more satisfactory than the mere provision of monetary compensation for damage. It might be the nearest possible equivalent to the restoration of a right of support.

45. Upon this aspect of the matter three suggestions were elaborated in the evidence, and are discussed more fully belowthe first of them affecting the process of mining, the second and third affecting the siting and construction of surface buildings.

These were (a) hydraulic stowage, and more scientific methods of mining;

(b) scientific lay-out of the surface;

(c) precautions possible in the construction of surface buildings.

46. With regard first to hydraulic stowage, many witnesses having suggested that this method of packing should be made compulsory in this country, we considered it desirable to obtain full evidence as to the working and cost of the system elsewhere. For this purpose we called in evidence Major H. M. Hudspeth, one of H.M. Inspectors of Mines, who submitted to us the results of an exhaustive study at first hand of the conditions with respect to hydraulic stowage which obtain in France, Belgium, Germany and more particularly in Upper Silesia.

47. Major Hudspeth's general conclusion is that hydraulic stowage undoubtedly reduces surface damage to a minimum, though it may increase the actual area over which subsidence occurs. It has, too, the collateral advantage of preventing spontaneous combustion underground. Its universal adoption in Great Britain is, however, impracticable, firstly because of the

cost, which Major Hudspeth puts at 1s. per ton even in the most favourable circumstances; secondly, because of the scarcity of suitable stowing material (except, perhaps, in a very few areas such as South Staffordshire); thirdly, because it is unsuitable for longwall workings-the most usual form of workings in this country; and fourthly, because the natural conditions at many pits are unfavourable, e.g., the seams are flat and thin, or the conditions of roof and floor are such that the introduction of water underground would be fatal to the working of the mine. Hydraulic stowage might, however, in exceptional cases be desirable and even economic; and we have it in evidence that it is in fact being advantageously employed to some extent at Motherwell,* where the cost is estimated at 1s. 3d. per ton.

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48. It may be recalled, in this connection, that under the Mines (Working Facilities and Support) Act, 1923, power is specifically given to the Railway and Canal Commission, in granting applications for the imposition of restrictions upon the working of minerals required for support, to include restrictions upon the methods of working or packing " (Section 8 (6) ). In the case also of applications for a right to work minerals, the Commission are empowered, in granting the right, to impose such terms and conditions as they may think fit (Section 6 (1)), which clearly might include one that hydraulic stowage be employed. In point of fact, however, we understand that in none of the Orders so far made under the Act has any obligation to employ hydraulic stowage been imposed.

49. In so far as concerns methods of mining, we are advised that the least damage is caused where the workings are advanced regularly and quickly by longwall, preferably by machine cutting, and where packing is tight. More regular and even working tends to avoid actual surface damage by making the subsidence less uneven.† Longwall working is, however, not always possible; for example, in very thick seams, and also where the roof is bad, bord and pillar working is necessary. A systematic examination of the effects on the surface of the various methods of working is, we understand, in contemplation by the British Colliery Owners' Research Association. We trust it will not be delayed, for such an examination should be of great value in regard to the economic development both of surface and minerals.

50. With reference to the lay out of the surface, the second of the above suggestions, we have already referred to the disadvantage of building houses in long terraces and the advisability of constructing them in blocks of two or four instead.

Hudspeth Q. 6378-9. See also "Hydraulic stowage at the Dalzell and Broomside Collieries, Motherwell," a paper read by Professor R. W. Dron before the Institution of Mining Engineers at their General Meeting (November 29th, 1923).

† Redmayne QQ. 1300, 1399. O'Donahue QQ. 1508, 1520. Evan Williams (5) 19th Day, p. 545. Also QQ. 7590-2.

This, as we have indicated, is the growing modern practice. The more scientific "zoning "and development of the surface according to the current conceptions of Town and Regional Planning should also do much to mitigate the damage caused by subsidence.

51. We are informed that provision can be made under Town Planning schemes not only for the separation of industrial and residential areas but also for the prevention or special regulation of building or other surface works on land liable to subsidence. and that a scheme may specify, e.g., the number of houses to the acre, the number of storeys in a house, and the maximum number of houses which may be built in one continuous block. It is to be hoped that the Authorities responsible for the preparation and administration of such schemes will take advantage of the very wide powers conferred on them by the Town Planning Acts. In this connection it is obviously desirable that these Authorities should have the fullest available information as to existing and prospective mineral workings and their probable surface effects. We make further reference to this point in paragraphs 76 and 126 of this Report.

52. With reference to the third suggestion, expert evidence tendered to us, particularly by Dr. Oscar Faber and Colonei Arthurt, shows that by suitable precautions in construction taken at an expense which, although in some cases proportionately serious, is rarely out of the question, the greater risks of damage to buildings due to subsidence can be avoided.

Dr. Faber expressed the view that ordinary brick buildings would suffer much less from subsidence if lime mortar were replaced by cement mortar, the tensile strength of the latter being many times greater. The resulting increase of cost would not exceed two or three per cent. In his opinion it would be possible to secure practically complete protection against damage by subsidence at an additional cost in the worst cases of not more than fifty per cent., and in the great majority of cases. of much less. Generally speaking, the larger the building the less would be the proportion of additional cost involved. For very tall buildings a steel framework would even be cheaper than brickwork. The ordinary miner's cottage in a mining area would, he considered be perfectly safe if built of ordinary brickwork with cement mortar on a properly constructed ferroconcrete raft. It seems true that in some cases the additional cost would still be prohibitive; but not so in all, and with constantly improving methods of construction its tendency would always be to decrease. Colonel Arthur considers that even now comparative safety would be attained at an increased cost of from two to nine per cent. for houses of the type erected under the 1919 Housing Act.

18th Day, p. 533, etc. † 15th Day, p. 410, etc.