MINING 385 



Some important researches were communicated in 1912 by J. S. Haldane and 

 T. Lister Llewellyn, to the South Staffordshire Institution of Mining Engineers 

 (Trans. Inst. Min. Eng., Vol. xliv, p. 267). Their experiments were designed with the 

 view of producing a vitiation of the atmosphere similar to what occurs in the ordinary 

 working of a mine. The result showed that every diminution of o.i per Cent in the 

 oxygen present lowered the illuminating power of a safety lamp, burning a mixture of 

 colza oil and paraffin, by as much as 3.5 per cent; and the striking fact is deduced that 

 with the oxygen reduced to 19.0 per cent, the minimum percentage allowed by the Coal- 

 Mines Act for purposes of ordinary work in the pit, the light would be diminished by 70 

 per cent, under the conditions of the experiment. It has been found that for every in- 

 crease of i per cent in the moisture of the air the illumination of the standard pentane 

 lamp and also of the Hefner amylacetate lamp falls off by 6.25 per cent, and the light 

 from a spermaceti candle falls off by 5 per cent. The authors also call attention to the 

 confusion which has arisen through attributing to carbon dioxide the premier role in 

 producing dimness of illumination. In their view it is only the variation in true oxygen 

 percentage that matters in a practical sense, and how this percentage is diminished is 

 of small importance, although it is true that added carbon dioxide does produce rather 

 more effect than added nitrogen. 



A point which has not yet been covered by the above experiments is the relative 

 behaviour of various kinds of illuminants. Burrell and Seibert (U.S. Bureau of Mines, 

 Technical Paper 13, 191-1) found that there was a remarkable difference in the composi- 

 tion of the residual air that extinguished the flame of a Wolf spirit lamp as compared 

 with that of an acetylene lamp. Thus, acetylene will apparently only cease to burn in 

 an atmosphere containing as much as 6.3 per cent of carbon dioxide and as little as 11.7 

 per cent of oxygen, whereas 3 per cent of carbon dioxide and 16.5 per cent of oxygen 

 marked the limiting composition of air capable of supporting combustion of a Wolf 

 lamp. The general use of acetylene lamps in coal-mines is frequently asserted to be 

 impracticable; but this scarcely agrees with the experience recently recorded in a 

 Spanish mine, where a Tombelaine acetylene lamp has been found to work satisfactorily 

 in a very fiery pit, and also to be capable of being used as an efficient gas detector. 



One result of these experiments is to point more strongly to the fact that the only 

 satisfactory solution of the illumination problem in mines will ultimately prove to be the 

 electric lamp, which is free at least from the deterioration arising from atmospheric 

 influences. If ever a means is found whereby the electric lamp can be adapted to the 

 detection and accurate estimation of firedamp, it will be at once established par excellence 

 as the miner's lamp. A handsome prize has now been offered by the German mine- 

 owners with a view to the invention of some satisfactory device of this nature. 



In May 1911 the British Home Office announced a prize of 1,000 for the best 

 electric lamp suitable for miners. The judges (Messrs. C. H. Merz and C. E. Rhodes) 

 awarded the first prize of 600 to the "Ceag" lamp sent in by F. Farber, of Dortmund. 

 In the " Ceag " lamp the bulb is protected by spiral springs so arranged that the circuit 

 it is broken when the surrounding dome glass is shattered. 



An important feature of the work of Haldane and Llewellyn is its relation to the 

 prevalence of miners' nystagmus. A paper on this subject was read before the Royal 

 Society by Dr. Llewellyn, who is the first Tyndall Research Mining Student. He con- 

 cludes that, whilst the disease is one of extreme complexity and one in which many 

 factors are at work, the chief factor is strain caused by deficient light, and that the most 

 important preventive measure is ^improvement in the lighting power of the miner's lamp. 

 This view was adopted by the Ophthalmological Congress at Oxford 1912. 



An interesting new safety lamp of great power, the Goulet incandescent lamp, has 

 been tried at the Frameries Station, in which an Auer mantle is raised to incandescence 

 by the flame of a mixture of air and benzine. 



WINDING. The use of electricity for winding purposes has made rapid progress 

 during the last three years, and is now being applied to plants of much higher capacity. 

 There are, broadly speaking, two systems, using in the one case an alternating-current 



