2 REPORT ON THE RELATION BETWEEN 



and the atmosphere of a mine may thus become explosive from a want of 

 sufficient air, oiving to a sudden increase of atmospheric temperature. 



There are two distinct and essential conditions necessary to cause an ex- 

 plosion in a coal-mine : — 



1st. The atmosphere of the mine must be rendered inflammable. 



2ndly. The inflammable air must be ignited. 



The condition of inflammability may occasionally arise from a workman 

 unexpectedly breaking into a reservoir of accumulated gas ; from the fall of 

 the roof of a Goaf, or old waste ; or from the accidental derangement of the 

 ventilating machinery. Such fortuitous cases do not belong, to the present 

 inquiry. 



As the instant of ignition is independent of the weather, and is generally 

 determined by an individual act of carelessness, it is obvious that any reason- 

 ing based on the action of the barometer or thermometer just at the time of 

 explosion will be apt to lead to conflicting and even erroneous results. This 

 will appear more plainly from a brief consideration of the attempts that have 

 been made hitherto to determine the relation between explosions in coal-mines 

 and atmospherical fluctuations. 



In the minutes of evidence on " Accidents in Coal-mines," taken before a 

 Select Committee of the House of Lords in 184-9, is a table, constructed by 

 J. Hutchinson, Esq., M.D., of thirty of the "chief explosions" since 1800 in 

 Northumberland and Durham, with one daily reading of the barometer and 

 thermometer at Newcastle-upon-Tyne, for each of three days, of which the 

 day of explosion is the last. The mean action of the barometer on the thirty 

 days of explosion is found to be a depression of '02 (two-hundredths) of an 

 inch ; and that of the thermometer an elevation of one degree. Hence it is 

 concluded that the relation between such explosions and the barometer is 

 "feeble" compared with their relation to the thermometer (Pari. Report, 

 &c., 1849, p. 154). 



T. J. Taylor, Esq., an eminent colliery-viewer in the North of England, 

 has selected twenty-five of the " great pit-explosions " in the same district, 

 and likewise tabulated a single barometrical reading at Newcastle-upon- 

 Tyne, for each of three days, of which the second is the day of explosion 

 {Idem, p. 557). 



These tables have been generally accepted as conclusive against the con- 

 nexion between a falling barometer and explosions in coal-mines. In a par- 

 ticular instance, where a great fall of the barometric column immediately 

 preceded a fatal explosion, a Government Inspector of Mines cites these 

 tables as the basis of his opinion that the fall of the mercury had no effect in 

 producing the explosion referred to (Pari. Report, &c. 1853, Qu. 543, 568). 



The following considerations will show that the nugatory result of these 

 tables is really no evidence of the absence of meteorological influences. 



1st. By selecting the explosion for the critical phcBnomenon of the inquiry, 

 the numerous cases are excluded where explosions have been foreseen and 

 prevented, when the atmosphere of the mine has been observed to have become 

 highly inflammable before it was too late to retreat. Two instructive instances 

 of this kind are mentioned in a letter of the 24th Sept. 1839, from T. D. 

 Brown, Esq., the owner of Jarrow Colliery, published in the Appendix to the 

 able Report of the South Shields Commi'ttee. Mr. Brown writes, " On the 

 1st Sept. I find the barometer stood at 28-81 inches. The master-wasteman's 

 account of the state of the air in Jarrow pit on that day is, that it was so bad 

 that the gas came to the shaft. On the day of the great storm (7th January, 

 1839) my barometer was down to 27*48 inches, and the wasteman's account 

 J8, that he seldom, if ever, knew a pit to be in such a state. The gas came 



