438 



NATURE 



[February 2, 191 1 



there is a preponderance of explosions about the time that 

 the central areas of anticyclones lie over our own coal- 

 fields. Until Prof. Louis can prove that this statement, 

 made by an independent investigator, is wrong, those who 

 study the question with an open mind will not readily 

 acquiesce in his theory, which requires the presence of a 

 cyclonic area to bring about a disaster. True, Mr. 

 Dobson's report to the British Association, and the papers 

 to the Royal and the Meteorological Societies by Messrs. 

 Scott and Galloway, were based on the theory that a low 

 and falling barometer was necessary ; but a glance at 

 their diagrams is sufficient to show that accidents under 

 a high barometer were attributed to a falling barometer 

 at some other time, Mr. Dobson going so far away as a 

 fortnight from an explosion to get a barometric fall to 

 satisfy the theory. But when Messrs. Scott and Galloway 

 had completed their inquiry from the purely theoretical 

 side, the diagrams were ready, and the percentages of 

 accidents under different conditions had been worked out, 

 recourse was had to the very simple device of looking up 

 the facts. • Mr. Galloway was permitted to examine a 

 large number of report books kept at mines in Scotland 

 in 1873. To the amazement of the authors, they " found 

 that sometimes a sudden fall of atmospheric pressure has 

 taken place without causing gas to appear, and some- 

 times gas has suddenly appeared in considerable quantity 

 when the pressure was high and steady." Before the 

 Royal Commission of 1879-86, an experienced mining 

 engineer, Mr. F. Wardell, stated that from his own 

 observation explosions occurred generally on a rising 

 barometer ; and Mr. (now Sir) Henry Hall, the well- 

 known Inspector of Mines, declared : — " More of the large 

 accidents that have happened in my hands have happened 

 when the glass was high, than otherwise." Evidence in 



an intimate relationship between the movements of the 

 barometer and the pressure of the gas existing in sealed- 

 up places in the earth — not the gas m the open goaf, 

 which is acted upon directly by the air-pressure. The 

 gauge inserted in the sealcd-up reservoir of the Hutton 

 seam showed that on every occasion when the barometer 

 rose, even as on March 24, 188 1, when it was at a very 

 low level, the imprisoned gas showed an out-bye pressure, 

 indicating that it was being compressed (Fig. i). When the 

 barometer was at its lowest, the compression ceased, and 

 the gauge indicated an in-bye pressure. Those who dis- 

 cussed the observations were mystified ; they could not get 

 over the facts disclosed, and the only escape from the 

 dilemma was by deciding that it« was all the fault of the 

 barometer — that it was riot sensitive enough to fall twenty, 

 thirty, or forty-eight hours sooner than it does ! No 

 physicist who has studied the action of the instrument 

 would admit that, even supposing there is any lag, it 

 would amount to as many seconds. It is a more reason- 

 able suggestion that the increase of barometric pressure- 

 weighs down the earth's crust, and this, acting upon the 

 imprisoned gas, increases its pressure. It is under these 

 high-pressure conditions that Colliery Warnings have bri r, 

 issued through three decades, and it is under these sani' 

 conditions that the worst explosions take place, for the\ 

 are associated with great outbursts of gas flooding the 

 workings suddenly, and not with the almost inappreciable, 

 regulated flow of gas from the open goaf under a low and 

 falling barometer. 



The Author of the Warnings. 



Fig. 



support of these statements could be multiplied to any 

 extent, and those who are interested in 'the question, 

 instead of treating the evidence as merely amusing, should 

 seriously endeavour to arrive at a reasonable explanation 

 of the appearance of dangerous volumes of gas in mines 

 when the barometer is rising or stands high. 



There was a time when, no one guessed that the earth's 

 crust was always on the move, wobbling like a jelly ; but 

 Darwin started a new idea, declaring that the time would 

 come when scientific men would no more regard the earth 

 as immovable for any length of time than they would 

 believe in an everlasting calm in the atmosphere. Since 

 that declaration we have advanced a long way on the 

 road towards proving the earth's crust, no longer sup- 

 posed to be a rigid mass, liable to rise and fall under 

 the vast changes of atmospheric weight indicated by baro- 

 metric variations. To miners it has been a matter of 

 common observation that earth movements are of frequent 

 occurrence, , and the evidence before the Royal Com- 

 mission of 1879 showed that strong rock-roofs are either 

 actually forced down or become much curved, eventually 

 recovering their normal position when the gas-pressure is 

 diverted in some other direction. The great disaster at 

 Abercarne on September 11, 1878, when 268 lives were 

 lost, had been preceded by outbreaks of gas daily from 

 September. 5 to 10, consequent upon a. squeeze or settling 

 down. Since the beginning of the month high barometric 

 pressure had ruled — 30-25 inches at .Abercarne on the day 

 of the disaster. 



The Seaham records demonstrate clearlv that there is 



I AM delighted to find that my article on this subject 

 has drawn a reply from the Author of the Warnings, 

 though I must admit to disappointment at the character 

 of his letter. In my article I stated 

 certain facts as to the occurrence of 

 fiiedamp in collieries, and showed how 

 this gas must behave under varying 

 barometric pressure in accordance with 

 well-known physical laws ; to my 

 mind, there is only one proper way of 

 controverting conclusions thus arrived 

 at, and that is to show where I am 

 mistaken in my statement of facts, in 

 my enumeration of the natural laws, 

 or in my deductions from these 

 premises. This, however, is precisely 

 what the .Author of the Warnings has 

 not even attempted to do ; he has pre- 

 ferred to be guided by the old solicitor's 

 maxim : " When you have no case, 

 abuse the plaintiff's attorney." 

 I do not propose to follow the Author of the Warnings 

 in the personal tone that he has introduced into the dis- 

 cussion, except to, say that the theory — if theory it be — i 

 that a falling barometer is apt to correspond with an] 

 increase in the , percentage of firedamp in the air of J 

 collieries is certainly not my theory, and originated long] 

 before my time. As the .Author of the Warnings implies-j 

 that these views necessarily connect colliery explosions! 

 with a low barometer, it seems worth while repeating thatj 

 this is not my opinion ; all that I maintain is : — 



(i) Barometric variations are only -a contributory cause,] 

 and a relatively unimportant one, of colliery explosions. 



(2) A falling barometer, or, to be more precise, a flatten- j 

 ing downwards of the barometric gradient, is apt to be! 

 accompanied by an increase in the percentage of fire-rl 

 damp in the air of mines. 



Thus W. Kohler has shown that a slow increase in' 

 the percentage of firedamp may be due to a steady high 

 barometer, or even to a slow rise following upon a 

 very rapid one, i.e. to a flattening of the barometri 

 gradient. 



The Author of the Warnings appears to attach much 

 importance to the Seaham Colliery records. Seeing how 

 fiercely he has accused everyone else of only using such 

 facts as suit them, it might be expected that he, at any 

 rate, would be above reproach in this respect ; unfortu- 

 nately, however, it would be difficult to find a worse 

 offender than he is in the use he has made of these 

 records. In the first place, he ought to have made it 

 clear that these records do not show gas pressure in a 



NO. 2153, VOL. 85] 



