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pheric air. This singular property imparts a facility to the 
gas, of which a perfect system of ventilation ought to take 
the most careful advantage. Its natural tendency being to 
ascend, with a degree of activity and force proportioned to 
its peculiar lightness as compared with the surrounding air, 
nature herself would seem to dictate the kind of arrange- 
ment which should be provided for the escape of so treacher- 
ous a foe, and surely this would be to reverse a great deal of 
that we now witness in practice. 
It hfts been already suggested, that existing systems have 
professed to take cognizance of the natural habit of the gas 
here referred to, and the workings have obtained a supposed 
assimilation to the direct form of evils, by affecting the 
equilibrium of all parts of the mine, in the proportion due to 
the length of the up-cast shaft, and the degree of rarifaction 
produced and kept up in it. The theory may be accurate 
enough, but in practice it is utterly fallacious. 
In the case of a coal mine we have a series of isolations, 
which, from causes already referred to, escape the general 
current of ventilation, and thus become stagnant pools or 
receptacles of gas, which answer to the term we have pre- 
viously used as undrained " goaf." 
Without stopping to discuss the very probable relation 
in which these "goafs" have stood to every instance of 
extensive explosion, we may remark, that their constant 
drainage or ventilation, has always been held a great desider- 
atum. The operation has not, however, been thus far 
accomplished. And so long as the leading currents of 
ventilation, are forced in directions, directly opposed to the 
habit which, the lighter and more dangerous gases naturally 
obey, isolation must continue, and with it those magazines of 
danger and of death, which make the use of the safety lamp 
necessary and imperative. Harmonize the direction of such 
currents and habit, and the result must go far towards 
