Reviews — Talceontographical Society. 325 



cliaracter of the air in a,ll parts of th^e pitj and possibly in causing an 

 explosion in a place which would have remained safe had the ven- 

 tilating current itself remained pure. It was shown how, when an 

 explosive mixture had been formed in places, and under conditions 

 similar to those described, some time — ■possibly several days — must 

 elapse before the contents of such an accumulation of dangerous 

 gases shall have been rendered innocuous again. 



The effect of warm weather in stopping natural ventilation was 

 explained, the natural temperature of a mine of a depth of 50 fathoms 

 being 55 degrees, that of one of the depth of 200 fathoms 70 degrees, 

 and so on. Speaking generally, it was shown that if the temperature 

 of the air rose to 55 degrees, natural ventilation must cease in shallow 

 pits; and similarly in other cases. Accordingly, if a warm day 

 occurs in the cold season of the year, and the furnaces are not in 

 action, an explosion is very likely to occur. 



These statements were illustrated by one instance of a fatal ex- 

 plosion, the cause of which had been declared by tlie inspector to be 

 inexplicable, the pit having strong natural ventilation. It appeared, 

 however, that the explosion occurred on a warm day, while the 

 inspector visited it twice on colder days after the explosion, so that 

 the state of ventilation which lie witnessed had no reference to that 

 which must have prevailed when the accident happened. 



The paper concluded by stating that it appeared that the evidence 

 fairly justified the view that meteorological changes were the proxi- 

 mate causes of most of the accidents, it being remembered, as has 

 before been observed, that the records contain no account of the 

 number of times when the pits have been too dangerous for the men 

 to go down, and so explosions have not happened. Whatever be 

 the meteorological changes, it is absolutely necessary to keep a most 

 careful watch over the amount of air passing through the workings. 



Thirty years ago, George Stephenson said, in a letter to the South 

 Shields Committee, referring to explosions — " Generally speaking, 

 there has been some fault in the ventilation of the mines when 

 accidents have happened," and the same opinion is held by many of 

 the most experienced authorities at the present day. In this matter 

 the one cry, whether we look to security against explosion, or to the 

 affording to miners an atmosphere which they can breathe without 

 injury to health, is— "More air." 



I.— PAii^ONTO&RAPHioAL SooiETY. VoL. XXV. Issucd for 1871. 



June, 1872.1 



AGAIN it is our pleasant task to record the issue of another 

 annual volume of the publications of this most useful Society, 

 which devotes its funds to the illustration of British fossils of all 

 ages, and has already issued many monographs and hundreds of 

 plates of Mammals, Eeptiles, Molluscs, Crustacea, Echinoderraata, 

 Eadiata, Fossil plants, etc., etc. 



' The notice of vol. xxiv., issued for 1870, will be found in tlie Geol. Mag., 

 Tol. VIII., 1871, p. 175. 



