December 18 1914. THE COLLIERY GUARDIAN. 1271 - IlilUIULl ’A N1 | MIM | m Fig. 12.—General View of Coke Oven Battery from Loading Side. VA-» ■ Fig. 13.—General View of Purification Plant. The quenching water pumps are provided in a separate building. All other pumps are arranged in the basement of the exhauster house. For permission to inspect this installation, the writer is indebted to the courtesy of Messrs. Henry Stobart and Company Limited, and for the use of the illustra- tions reproduced herewith to the contractors, Messrs, the Simplex Coke Oven and Engineering Company Limited, of Sheffield. Hull Coal Exports.—The official return of the exports of coal from Hull to foreign countries for the week ending Tuesday, December 8, 1914, is as follows :—Ahus, 1,512 tons; Buenos Ayres, 4,145; Bergen, 2,303; Christiania, 993; Copenhagen, 299; Karachi, 395; Dunkirk, 2,533; Dieppe, 938; Drontheim, 2,303; France, 1,946; Gefle, 3,204; Gothen- burg, 831; Harlingen, 557; Halmstadt, 737; Honfleur, 691; Hallsta, 1,265; Leghorn, 301; Malmo, 1,417; Naples, 694; Nakskov, 746; Oxelosund, 1,811; Rouen, 10,702; Ronneby Redd, 1,987; Rosario, 3,981; Rotterdam, 103—total, 46,444 tons. The above figures do not include bunker coal, ship- ments for the use of the British Admiralty, nor the Allies’ Governments. Corresponding period December 1913, total 80,670 tons. South Staffordshire and Warwickshire Institute of Mining Engineers.—The next general meeting will be held at the University, Edmund-street, Birmingham, on Monday after- noon, December 21, at 3 p.m. A lecture entitled “ The Formation of Coal Seams in the Light of Recent Microscopic Investigations, and its Influence on Modern Mining Problems,” will be given by Mr. James Lomax. This lecture will be illustrated with numerous micro-sections and an illuminated section of a South Staffordshire and Warwickshire coal seam. Provision of Surveying Instruments.—A letter from the Home Office was read at a meeting of the Carmarthenshire Education Committee at Carmarthen last week, pointing out that working miners had a difficulty in qualifying for the colliery manager’s certificate owing to their inability to obtain practical experience in mine surveying with the necessary instruments. The Home Office thought the diffi- culty could be surmounted by education authorities providing surveying instruments for the use of their mining classes, and securing access for the students to the mines in their areas. The coal owners and managers should be asked to provide the necessary facilities. The chairman (Mr. W. N. Jones) said he did not think there would be the slightest difficulty in getting the consent of the coal owners. In some collieries the students might have the use of the surveying instruments. The mining committee was directed to carry out the suggestions of the Home Office. SUPPLIES OF PIT TIMBER. Colonial and Native Sources. The Board of Agriculture have just issued a useful leaflet relating to the supplies of pit timber. The amount of pitwood used in the United Kingdom is estimated approximately at 4,500,000 tons, or 1'7 per cent, of the total weight of coal raised. The great bulk of the pitwood used in this country during normal times comes from abroad, the amount of the home supplies being probably not more than 20 per cent, of the total consumption. In recent years the quantity of pitwood imported has amounted to about 3,000,000 loads of 40 cu. ft. per load. About 55 per cent, of the imports normally come from Russia, Sweden and Germany, 4 per cent, from Norway, and the remaining 41 per cent, from France, Portugal and Spain, the proportion varying a little from year to year; the imports from other countries have been relatively very small indeed. Pit props have been declared contraband of war by the German Government, and trade with the Baltic ports has consequently been seriously hampered. In any case the seasonal pitwood trade with Northern Europe would almost cease with the approach of winter. On the other hand, supplies from Southern Europe will probably continue to arrive so long as there is available sufficient labour to prepare the material. The Board < f Trade have sent a committee to Canada to investigate the possibility of meeting the deficit fi om that source, but it is unlikely that such pitwood could reach this country before February 1915. In the meantime supplies of home-grown timber must be relied on to meet the deficiency. Type of Material Required. The timbers chiefly in demand for pitwood are those which combine strength with lightness. Where the roof of the mine is dangerous it is also of importance that the timbers should be of such a character that they give warning of impending movements by gradual fracture; brittle woods are in such cases unsuitable. As a result of experiments made by Prof. Henry Louis at Armstrong College,* it has been found that seasoned props have a distinct advantage in strength and durability over unseasoned props ; no timber should, in fact, be used for pit props while it still contains sap. The absence of large knots or of even slight curves is also of importance, since when present they form points of weakness at which an otherwise sound prop readily gives way. The timber which comes from the North of Europe is either Scotch pine (redwood) or spruce (whitewood), and it reaches the mines in the form of clean, straight pieces, sawn into suitable lengths and devoid of bark. It is usually sold at a rate per hundred lineal feet, the price varying with the diameter of the props. The material from France and South Europe is maritime pine. In this case the timber is shipped in sawn lengths which are unpeeled, the larger sizes being sometimes rather rough from being subjected to the process of tapping for resin. This timber is used chiefly in the South Wales coalfields, where it is sold at a rate per ton. The three species mentioned in the preceding paragraph represent the bulk of the timber used for mining purposes, but are generally less esteemed than larch. Larch is stronger than any of the other three timbers, is more resistant to fungus attacks and consequently better suited for permanent work, but is. on the other hand, more expensive. Hardwoods are also used to a small extent, but in normal times the only broadleaved species in any considerable demand is oak. In case of a shortage, however, chestnut, beech, birch, sycamore, elm, alder, &c., will doubtless be used to a much greater extent than formerly. Dimensions. The extreme diameters of poles used as pitwood are 2 in. and 13 in., but, although a good deal of slender timber is used in some districts and large timber in others, it may be said that as a general rule the minimum diameter of timber for which there is any considerable demand is 3 in., and that it is only in exceptional localities—e.g., ironstone mines, that poles of a greater diameter than 6 in. are used to any considerable extent. Pit timber is used in lengths ranging from 1J ft. to 18 ft. As a general rule the length varies with the diameter in the ratio of approximately 1 ft. to lin., but the precise dimensions depend upon the particular locality. The sizes in greatest demand in various localities are set out in some detail below. It may be stated briefly that in coal mining districts the greatest demand is for timber 3 to 6 feet long, although there is considerable demand for lengths as small as 2| ft. and as large as 7 ft. The leaflet describes and illustrates some typical methods of timbering. It is noted, however, that there is no standard practice, the systems used being adapted to the special characteristics of each particular mine. The timbers used for the framework of main galleries may be the ordinary woods used for pit props, but more substantial timbers such as sawn pitch-pine, oak and larch are also used Instead of timber, steel girders are in some mines used for “ caps.’’ “ Cogs ” are short pieces of timber about 2 or 3 feet long: they vary con- siderably in diameter, being frequently about 3 in. thick, but sometimes as much as 9 in. Old pit props and coppice wood are frequently used for this purpose. The length and diameter of the props vary with the thick- ness of the seam. In order to make the prop more effective a “lid ” is placed upon it to provide a greater bearing surface; the “lid’’ is about 15 or 18 in. long, 2 or 3 in. thick and 5 in. or so wide; it is frequently made of short lengths of pit props split in halves. * Transactions, Inst. Mining Engineers, vol. xv., p. 343.