330 THE COLLIERY GUARDIAN. Eebrtta.ky 14, 1913, ELECTRIC CABLES IN MINES * Export Trade. Mr. Huddleston’s history, E. I. R. exports. Calcutta Port Trust Admini- stration report, 12 months ending March 31. Railway Administration Report. Calendar years. Note on production and consumption of coal. Commercial Intelligence Department, calendar year 1911. Exports.* F. Noel Paton. Geological Survey net exports outside India and Burmah. To Indian ports, excluding Burmah. To ports outside India, but including Burmah. Tons. Tons. Tons. Tons. Tons. Tons. 1891 137,000 — — — — — 1892 — —• — — — — 1893 — — 1894 — 40,282 143,813 154,282 — — 1895 — 46,128 162.276 211,407 — 81,126 1896 574,000 105 842 389,842 191,030 — — 1897 — 386,490 731,742 390,979 — 5 — 1898 — 672,747 737,689 490,290 — — 1899 — 877,895 672,311 467,306 — — 1900 — 869,847 1,030,709 711,874 490,490 541,453 1901 1,995,000 1,469,915 1,157,892 845,953 587,871 — 1902 — 1,507,576 974,602 728,316 430,115 — 1903 — 1,390,277 1,235,318 723,873 441,938 — 1904 — 1,651,491 1,447,867 896,885 602,810 594,850 1905 2,767,000 2.086,937 1,635,263 1,144,680 783,033 i 836,188 1906 — 2,558,502 1,830,793 1,394,732 1,002,951 ! 935,580 1907 — 3,000,181 1,865,056 1,040,242 658,145 ! ! 728,916 1908 — 3,000,795 2,124,642 1,045,695 659,596 i 571,621 1909 — 2,971,174 1,716,823 912,154 563,940 — 1910 — 2 744,391 1,851,322 1,391,248 988,366 1 988,3661 1911 — 2,991/97 — — 862,177 1 862,177/ i i These two columns deal with These three columns deal with true exports from gross exports from Indian ports. India. * Excluding bunker coal, private merchandise. f Calendar years. By G. W. T. Anderson, M.Inst.M.E., M.I.E.E. At the outset, one was. bound to refer to the enormous influence brought to bear on the subject by the intro- duction of the new Home Office rules governing the installation and use of electricity in mines—an influence which there could be no manner of doubt must not only result in a considerable saving of human life, but also in a much more satisfactory state of affairs both to owner and manufacturer, on account of the ^standardisation of conditions by a group of absolutely impartial engineers. The greatest influence that the new rules have upon ,! cables related undoubtedly to the question of armour and its conductivity. The new rules also affect the cables in two other most important directions, namely,. as regard their fittings and the question of earthing, for which latter it was now recognised that the steel wire armour provided the most suitable path from switch- boards and motors inbye. Types of Cable and their Relative Efficiencies. The first question which confronts the mining man who proposes installing electric light or power below ground is the choice of cables, which for convenience may be readily divided into four headings, namely: (1) rubber, (2) paper lead covered, (3) paper leadless, (4) bitumen. Rubber.—Under normal circumstances this is undeni- ably the best from both physical and electrical points of view. It may also be said that, on account of cost, it is commercially almost impossible for large cables. In small lengths, however, rubber cable (generally treated with fire-resisting braids and compounds) is nearly The three or four coal companies which were in existence 50 years ago have risen to 70, who are recorded in the Calcutta financial paper Capital, April 1911, besides others below mentioned. The 70 are recorded as having issued: Rs. Ordinary shares........ 390,42,924 Preference „ ........... 10,00,000 400,42,924 or £2,669,000 and to have a block valuation of Rs.467,31,285, or £3,114,000. The shares of some of these are at a premium of several hundred per cent., and some at a discount of 90 per cent., so that it is almost impossible to compare the actual and nominal value of the aggregate capital invested. There were 47 companies up to 1906 ; 32 were added in 1907 ; 30 were added in 1908 ; two were added in 1909 ; but a reference to the chart and figures of out- turn will show that this mushroom growth had little proportional effect on outturn. Besides the above there are a number of privately owned collieries, three large London companies, viz., Hyderabad (Deccan) Company, which works Singareni, the Indian Collieries Syndicate Limited, which operates in Jerriah, and the Assam Railway and Trading Com- pany, which works the Assam Collieries at Makum. These three collectively turn out about 1,100,000 tons. In addition to these, again, are the Umaria Colliery, which in 1908 turned out 155,000 tons, and the collieries owned by the railways (the principal being the East India Railway’s Colliery at G-iridi), which are returned by the Railway Administration Report for the 12 months ended March 31, 1911, as totalling an outturn of 793,493 tons, with a capital expenditure of Rs. 5,317,836. No figures, however, give a better idea of the growth of the trade than the consumption of the railways themselves. The following figures are taken from the Railway Administration Report:— Foreign coal. Indian coal. Wood. Tons. Tons. Tons. 1905 ... 55,909 ... 2,638,855 ... 253,089 1906 ... 71,768 ... 2,829,365 ... 248,037 1907 ... 50,070 ... 3,285,443 ... 188,672 1908 ... 74,709 ... 3,559,028 ... 164,494 1909 ... 79,130 ... 3,663,280 ... 127,009 1910 ... 52,147 ... 3,771,247 ... 127,725 The Bengal Nagpur. Railway can now carry coal to Bombay and Madras, which route competes with marine transport vid Calcutta. It was stated at the last meeting of the Bombay Millowners’ Association, held at the end of March 1912, that the import of coal into Bombay was nearly 1,150,000 tons, and, of this, 45,000 tons came rail; and comment was made on the primitive, wasteful and costly method of landing, by means of lighters, coal from steamers at anchor in the harbour. The coal trade of India has developed in direct proportion to the facilities of transport. We have seen expansion fitfully promoted by “booms” and retarded by collapses in trade. These have been emphasised by and at the same time have reacted on the provision of railways and of rolling stock. The car of progress of the industry has been drawn forward by many forces pulling not together nor continuously, but intermittently, each member of the crowd at times C )Al. BOOM 12.700.000 TONS E EST OESHURGiHUh COAL 4/ Ako bAraIbcIn11 oteNkHd >L TQPCSl LIKE EXTEND T0 (OkANG MIR — T0JE1RRAH AFTER THE BOOM rtCTURGHUR^--- Diagram Showing the Growth of the Output of Indian Coal. The prices shown are into wagon at colliery. 12 000.000 II. 000.000 10.000.000 9 000 000 8.000.000 7 000.000 6.000 000 5.000.000 4.000.000 3.000.000 2.000.000 i 000 000 hanging back or shouting to the others that he is not doing his share. Sometimes an extra pull has brought it on with a rush, and some of the pullers have fallen and been crushed under the wheels. Then there has been a halt till the forces are organised again. There has lately been such a halt, but at present general trade and the conditions created by the British coal strike are exerting a force which, if allowed to give a direct pull, would impart a great impetus to the Indian coal trade, by but the means of carriage have failed. The railways are blocked with traffic and short of wagons, and the scarcity of steamer space has forced up freight from Calcutta to Bombay to Rs. 8/8 per ton, more than double what it was a few years ago. I In view of the fact that the coalfields exist on the very edge of the great plain of Bengal and its network of rivers, and that water carriage is so mueh more elastic and suitable than railway carriage for mineral traffic, it seems strange to those who have studied conditions in other countries that this means of carriage has been wholly neglected in Bengal. We shall later revert to this subject. always used for making off, or tailing, cables of other description. And in this connection, nothing but the very best material should ever be used below ground: say, 2,500 meg. grade for low tension, and nothing inferior to that specified by the Engineering Standards Committee for high tension. There are also exceptional uses to which rubber cable can be put, principally in connection with breakdown work. One such example is given in the accompanying illustration (fig. 1). The cables shown were hurriedly rigged up to follow down a sinking pump in a flooded shaft. Working at a current density of about 3,000 amperes to the square inch, they were slung in the manner depicted, to prevent them becoming unduly hot. Paper Lead Covered Cable.—While this has advan- tages as regards withstanding heat from without, and ready dissipation of heat from within, consequent upon overload, paper has the disadvantage common to all fibrous materials of being more or less hygroscopic. * From a paper read before the Manchester Geological and Mining Society.