June 23, 1916. THE COLLIERY GUARDIAN. 1183 head baths mean a huge plunge bath in which hundreds of miners have to cleanse themselves, and that having to use a huge draughty building in which to dry and dress themselves must inevitably cause chills, or that the workers would have to be kept waiting long periods for their turn to use the baths, can only be got rid of by deputations of the miners being shown model instal- lations like those at Atherton (Lancashire) and Treharris (South Wales), where their actual operation can be seen and understood. The fear has often been expressed in some districts where the question of installing baths hasj been under consideration that the miners’ clothes might not be too safe left hanging in a dressing room, or that their pockets might be rifled, but when they can be shown their clothes suspended at a height of 20 to 30 ft. above the floor, and securely locked with the key in their own pocket, this prejudice will be dissipated. The provision of pit-head baths for miners would be a greater boon in daylight saving to both the miners and their women folk than that effected by the present Daylight Saving Act, particularly in the case of large families, where several members have to be “ tubbed ” before they are free to engage in any social intercourse or other recreation. Above all, those workmen who have long distances to travel on foot or by tram and train would I' J • •' • . - •” ' ..-.' fl ■ ■ " • ■ ■ ______ Fig. 7.—Drying Room with Racks. be benefited to the greatest extent, and it is the lippe of those interested in the welfare of the miner in the South Wales coal field that the good example set by the Ocean Coal Company Limited at Treharris will be speedily followed at other centres in the coal field. SURFACE DRAINAGE. An item worthy of the consideration of every colliery owner or manager is that of efficient surface drainage. In mines the water question is only overcome in many cases at enormous expense and trouble, and that alone is evidence of its importance. It seems stupid at first to allow water into the underground workings and then pump it out, but this cannot be entirely avoided, though much can be done, and is often left undone, to mitigate the expense of pumping or the danger of letting the water in. The presence of water in mines carries with it two great dangers, the one caused by its rendering roof and pavement weak and the other the danger of flooding. The drainage of the surface is important, especially when the concession is comparatively flat, a point which should be considered when the position of the shaft or shafts is being decided upon. It may be found advisable to carry the travel of the workings against the general drainage direction, so that the subsidence will not cause water to accumulate. In flat districts the drainage should be made previous to working coal or other mineral, so that it will be able to drain the water when any lowering of tire surface takes place. All drains or ditches should be able to run off the heaviest rains quickly, and should be at all times quick running, as nothing is more favourable to the growth of certain plant life than stagnant water. This growth of vegetation, if allowed to accumulate, in time renders the drains or ditches useless. Where underground workings are near the surface or connected with older workings near the surface, it is often found expedient to puddle or cement the beds of brooks or streams if any exist in the immediate vicinity. Surface boreholes often prove another source of trouble by their acting as conduits or by their cutting feeders and allowing water to percolate more easily to the under- ground workings. After these boreholes have served their purpose they may be profitably filled up with either clay or cement. The danger of incoming water can easily be understood, as very often what would otherwise be a good roof is rendered friable when water or even moisture is allowed to touch it. Water percolating into lipes or vees will often extend the area of or start movement. Then, again, there is the usual danger attached to water in the mine, for though it is sometimes necessary in a dusty mine it is something of which one may get too much. An ex-soldier named James Wiltshire, aged 53, employed as assistant banksman at Priston Colliery, Tunley, fell a distance of about 245 yds. down the pit shaft, and was instantly killed by striking against the cage near the bottom. This happened about 2.40 a.m., and it is supposed that some steam coming up the shaft obscured his view when he was engaged at the bank. MANCHESTER GEOLOGICAL AND MINING SOCIETY, Visit to Llay Main Sinking. About 80 members of the society, under the leader- ship of Mr. J. Ashworth, visited the Llay Main Colliery, at Rossett, near Wrexham, on Monday last, and spent a very interesting and instructive afternoon inspecting the new sinkings now being put down by the freezing process, the contractors for which are Messrs. Simon- Carves Limited, Manchester. The colliery is situated in the parish of Gresford, and belongs to the Llay Main Collieries Limited. Railway and siding connection has been established by means of a private line, 11- miles long, with the Great Central Railway line at Cefn-y-bedd. The two shafts are 90 yds. apart, and are to be sunk to an estimated depth of 750 yds. each, to work the area of coal surrounded by the Bala fault, the Llay Hall fault, and the United Westminster Colliery barrier. No. 1 shaft has been sunk to a depth of 260 ft. through frozen ground, and tubbing put in to that depth; No. 2 shaft is at present in course of sinking. The shafts are 18 ft. diameter, and the strata to be sunk through comprise 47 yds. of glacial drift overlying the coal measures. Freezing has been carried out through the loose sand and water- bearing strata to a depth of 231 ft. The freezing plant con- sists of two entirely separate units, each driven by inde- pendent steam engines. The compressors are charged with anhydrous ammonia, which is driven from the compressor under pressure, and passes through the con- densers, and then through the regulating valves into HRB the evaporators, return- ing to the compressors to be re-compressed. The freezing medium is calcium chloride, and flows from the evaporators through the pumps into a main leading to the distributing circle placed in an enclosed freezing cellar around the circumference of each shaft; this is con nected by a branch lea l tube of 1 in. diameti. r to each of the bore- holes through which the brine flows, and then passes down an inside pipe to the bottom of the borehole, and returns up another, outside tube to a lead connecting pipe and into the collector circle; and returning once more to the main is led back to the evaporators to be re-cooled. There are 25 boreholes, each placed 3 ft. 3 in. centres ■apart at a diameter of 26 ft. 6 in., and each borehole is kept under control by valves on the inlet and return pipes. The boreholes were put down to an approximate depth of 231 ft. with the existing headgear by means of percussive boring; a centre hole has been put down at each shaft to water level to act as an outlet for the water when the ice ,wall is closed. Deviations were taken of each hole by means of the plumb wire system. The entire plant is arranged so that each machine can work separately on each shaft; or the full power can be concentrated on one shaft. The visitors were shown round the plant by Messrs. W. E. Shelley, F. Schmidt, and A. D. Brydon, who explained the various details and appliances of the freezing process. A highly interesting item of the pro- ceedings was the collection of cores from the borehole put down to prove the coal measures, the Brassey seam of which, containing 5 ft. 9 in. of coal (including 15 in. of cannel) was reached at a depth of over 2,300 ft. The cores, which range from 18 in. down to 2-38 in. in diameter, are in an.excellent state of preservation, and form a complete record of all the strata traversed. The boring proved the presence of all the seams known in the North Wales district, and was stopped at the main seam. After tea, Mr. John Gerrard (late H.M. inspector of mines) moved a cordial vote of thanks to Messrs. Simon- Carves Limited and the Llay Collieries Limited for the opportunity afforded the society of seeing such an interesting plant. The motion was seconded by Mr. W. Pickup, and carried with acclamation. In replying on behalf of Messrs. Simon-Carves Limited, Mr. F. Schmidt mentioned that the sinking was the first of its kind to be carried out in this country by a British firm, and said that he hoped that the process would be applied later on to some of the wet ground in the South Yorkshire coal field. Shaft Sinking by the Freezing Process. On Tuesday, Mr. Leonard R. Fletcher presiding, a paper on “ Shaft Sinking by the Freezing Process,” by Mr. Frederick Schmidt, of Paris, was read by Mr. Brydon, the engineer at the Llay Main Colliery, where the process is in operation. (See page 1184.) Discussion. On the motion of the President, seconded by Mr. Sydney A. Smith, a vote of thanks was passed to Mr. Schmidt and Mr. Brydon. Mr. S. A. Smith said he did not think the opportunity ought to pass without an expression of thanks to the owners and the engineers at the Llay Main Colliery for the interesting excursion provided for the members of the society on the previous day. Most of those who had the pleasure of examining the actual sinking of a shaft through water-bearing strata by the freezing process were struck by the simplicity of .the operation. Boreholes had been sunk round the circumference of the shaft, at the bottom of which sinking was being pro- ceeded with in a much simpler manner than any process he had seen before. Although simplicity seemed to be an outstanding feature of the work, there were several queries which occurred to the mind of a mining engineer. For example, he understood the boreholes were sunk every 3 ft. round the shaft, but how the engineer managed to get them absolutely vertical he could not quite make out. He saw the little model of the shaft, down which a copper wire was suspended with a weight at the end, and an explanation was given as to how the boreholes were sunk, but he did not yet understand how they got them vertical. Those particular boreholes were said to be 233 ft. deep, 3 ft. apart, and it appeared to him that in the course of the sinking they must have got more than 3 ft. out of the vertical. Mr. Schmidt replied that when the wire touched the side of the borehole the suspension point was changed. The deviation, generally speaking, was about | per cent.; not more. At any rate, it was not sufficient to make a second borehole necessary. 8.—Ambulance Room. Mr. Atherton asked whether each borehole was put down separately, or whether more than one was done at the same time. Mr. Schmidt : Two or three at the same time, three machines being used. It was not easy to work with more than three machines, because the space at their disposal was limited. Mr. Ollerenshaw (Denton) said that those who had the pleasure of visiting the Llay Main Colliery agreed that the method seemed to be a complete success, and, in his opinion, there need be no hesitation in the minds of anyone who desired to sink through water-bearing strata by the freezing method, because it had certainly passed through the experimental stage. Up to the present, however, no information had been given as to the method in which the holes were bored, or how the tubes were inserted. It would also be interesting to know what the author estimated would be the limit of depth to which the boreholes could be sunk, and the limit to which a shaft could be sunk through water- bearing strata. Mr. Schmidt observed that, for very deep shafts, the quick boring apparatus was generally used, because the period of preparation and boring was a vary long one. In several cases it was found that, with the quick boring apparatus, the deviations were more important than with the other apparatus. With regard to the depth of the shaft, there was no limit to the freezing process, but special precautions had to be taken where a great depth was reached. Mr. Ollerenshaw remarked that the heat of the earth increased the deeper one descended, and he wondered whether, after penetrating to a certain depth, there was a point at which freezing would not take place, or if it did, whether the heat constantly present in the earth would gradually destroy the shaft. Mr. Atherton asked whether, in deepening a shaft, an old river channel or something of that kind with running quicksand was met with, boreholes could be put in diagonally to freeze the strata.