1872.] 



between Explosions in Collieries and Weather. 



293 



especially in the shallower mines, where the tension of the gas is not great 

 and the fissures are open. On the other hand, the effect of a given quan- 

 tity of gas in rendering the air of a mine explosive must depend on the 

 supply of pure air to the workings. 



It has long been observed that when the barometer, after having stood 

 at a high level for a time, begins to fall more or less rapidly, the accumu- 

 lations of foul air and gas in the goaves and fissures of a mine emit part 

 of their contents into the ventilating-currents which flow past them. 



It is also well known that as the very existence of these currents de- 

 pends, in almost every case, on the difference of temperature between two 

 columns of air, those in the downcast and upcast shaft respectively, any 

 increase in the temperature of the external air, from which the downcast 

 shaft receives its supply, must necessarily render the circulation under- 

 ground more sluggish. 



It is therefore obvious that the tendency to explosion will be increased 

 when the ordinary causes which lead to the fouling of the air in a mine, 

 such as falls of roofs and leakages in the air-courses, are assisted from 

 without by the meteorological phenomena we have just mentioned ; and 

 several investigators have compiled lists of explosions, in order to compare 

 them with the meteorological observations which have been recorded prior 

 to and at the time of the accidents. 



At the Meeting of the British Association at Glasgow in 1855, Mr. T. 

 Dobson, B.A., read a paper " On the Relation between Explosions in Coal- 

 mines and Revolving Storms," which is printed entire among the Reports. 

 The reasoning in this paper is to a great extent based upon a diagram 

 given by Mr. J. Dickinson, Inspector for the North and East Lancashire 

 District, in his Report for 1852, which shows the daily march of the 

 barometer during that year at Manchester, and the explosions which oc- 

 curred in his district during the year. 



Mr. Dickinson, in his Report for 1866, gives a diagram showing a con- 

 tinuous barogram recorded at Manchester for one week (December 8-1 5th, 

 1866), characterized by a remarkable barometrical depression. Between 

 the 10th and 13th of December 463 lives were lost in six different explo- 

 sions, the two accidents at the "Oaks" Colliery causing 361 deaths. 



In the * Transactions of the North of England Institute of Mining 

 Engineers' (vol. xix.) diagrams are given showing the meteorological re- 

 cords from the Observatories of Kew and Glasgow for 1868 and 1869, and 

 the explosions reported during those years. No discussion is given, but 

 the diagrams have been carefully compiled by the secretary, Mr. Banning, 

 and we have extracted the list of explosions for 1868 from this paper. 



Lastly, in the 'Journal of the Austrian Meteorological Society' for 

 February 1872, Herr F. M. Simmersbach* has published a paper on the 



* "TJeber den Einfluss meteorologischer Vorgange auf die Luftcirculation unter 

 Tage, und auf die Gasgefahrlichkeit in den Koklgruben," von F. M. Simmersbach in 

 Dortmund, Zeitschrift der osterreichischen Gesellschaf't fiir Meteorologie, 1872, p. 37. 



VOL. XX. Y 



