221 



KNOWLEDGE. 



[October 1, 1895. 



LIGHTNING PHOTOGRAPHS. 



Photograph taken during the storm of August 22nd, 1S9.5 



A number of interesting 

 been taken during the 

 severe thunderstorms of 

 this summer. The first 

 of the two which are 

 reproduced in Know- 

 ledge this month was 

 talien by Mr. George 

 Primavesi, at Tooting, 

 during the storm of 

 Thursday, August 22nd, 

 at about 9 p.m. The 

 plate was exposed for 

 one second only, and 

 during that time but one 

 flash occurred, which, 

 as will be seen in the 

 photograph, was much 

 distributed. The second 

 photograph was taken 

 by Mr. H. J. Adams, at 

 Beckenham. Although 

 a much smaller flash, 

 it is an exceedingly 

 vivid one. 



photographs of lightning have 



Photograph of a vivid ilash taken at 

 Beckenham. 



COAL MINE EXPLOSIONS AND COAL MINE 

 FIRES; THEIR OCCURRENCE AND 

 SUPPRESSION. 



By D. A. Louis, Metn. Fed. Inst. Min. Eny. ; Mem. N. of 



Eng. Inst. Min. Mech. Ewj. : Mem. Aiiier. Inst. Min. En<j. : 



Mem. Min. Assoc. ((-Inst., Conuratl ; A'c. 



BESIDES sharing with other kinds of mining many 

 of the risks incident to such operations, coal 

 mining is, im fortunately, distinguished by having 

 dangers peculiar to itself. These dangers arise 

 from the character of the material mined, which 

 exhibits inflammability, friability, porosity, and pronc- 

 ness to association with combustible gases. The last of 

 these is the primary cause of all fire-damp explosions, 

 whilst to the other three we may look for an explanation 



of coal-dust fires, and for spontaneous combustion in 

 coal mines. 



These three phenomena — fire-damp explosions, coal-dust 

 tires, and spontaneous conflagrations — may be regarded as 

 pertaining particularly to coal mines ; for, although gas 

 explosions occasionally occur in metalliferous mines, such 

 occurrences are rare. One or other of these phfinomena is, 

 moreover, accountable for nearly all the calamities that 

 have ever befallen mankind in the pursuance of such 

 industrial operations. Consequently, coal mining is very 

 generally regarded as a particularly unattractive and 

 perilous occupation, and really this is not to be wondered 

 at, when one pictures the scene of a coal mine explosion^a 

 labyrinth of narrow passages pervaded by a pernicious 

 atmosphere, deep under the ground, only accessible from the 

 surface by one or two holes of comparatively insignificant 

 horizontal dimensions, but of great depth, the only illumi- 

 nation from feeble lamps scarcely equalling a candle in 

 power. Under such circumstances the sudden and appar- 

 ently unaccountable appearance of one of the catastrophes 

 —a gas explosion, for instance — presents a truly awful 

 picture, with its irresistible rushing current of flame, 

 smoke, and debris, carrying merciless destruction wherever 

 it can gain access ; this being succeeded by utter darkness 

 and a poisonous atmosphere, that asphyxiates those who 

 have by chance survived the force of the explosion-wave. 



But in spite of the truly terrible character of explosions, 

 and the apparent unattractiveness of the occupation, coal 

 mining, as a matter of fact, as carried on in the majority 

 of mines now-a-days, is not particularly perilous, and, so 

 far from being unattractive, even exerts a kind of fascinating 

 influence over many people. The writer of this paper is 

 acquainted with many individuals who really delight in 

 working in coal mines. In well-conducted mines, and 

 where circumstances permit, the passages are neither 

 tortuous nor very low, the atmosphere is excellent, and the 

 surface can be reached in a shorter time than it takes 

 to reach the upper part of a house of three stories ; while 

 the chances of an explosion are reduced to a minimum, so 

 that such occurrences are rendered as near to impossible 

 as human eflbrts can make them. This comparative safety 

 is attained by paying rigorous attention to all the points 

 that scientific investigation has from time to time indi- 

 cated as necessary, and to which attention will be drawn 

 later on. 



Coal mine explosions have occurred ever since mining 

 operations have been followed underground, and, un- 

 fortimately, we still find them occurring, for but recently 

 have we not read with horror the account of the explosion 

 at the Albion Mine '? Such disasters have naturally 

 always awakened strong feelings of sympathy and terror, 

 and emphatic demands for investigation ; consequently 

 they have been the subject of constant inquiry. Their 

 consideration has been the object of much labour of 

 commissions and committees, both British and foreign, 

 and they have provided a field of perennial fertility to 

 numerous investigators in practical science, ambitious of 

 earning distinction for themselves and at the same time of 

 doing good to mankind. 



In perusing many of these records one is struck with 

 the positiveness of the statements made, and with the 

 remarkable diversity of the opinions expressed, so that 

 one cannot help thinking that to this has been due the 

 long survival of coal mine explosions. We can, perhaps, 

 never altogether prevent mining disasters, but provided 

 we have unanimity in the views as to what is and what is 

 not dangerous, adequate precautions could and would be 

 undoubtedly adopted everywhere. 



Fire-damp explosions and spontaneous conflagrations 



