224 
COLLIERY EXPLOSIONS. 
is expressed by the Eoyal Commission on Accidents in Minesd 
They say, “ the variations of atmospheric pressure exercise an 
undoubted effect on accumulations of gas in mines. Some few 
observers believe the expansion of the gas from the places where 
it has been pent up takes place before an indication of the 
barometer. Others think that the issue of the gas follows the 
fall of the mercury. Very few observers believe in any important 
influence of atmospheric pressure upon the issue of gas from the 
face of the coal, holding that the extra volume of fire-damp thus 
given off would at all events be small in comparison with the 
capacity for diluting gas which should exist in the air.” . . . 
“ Although there can be no doubt that with a sinking barometer 
an additional quantity of gas has to be guarded against, very 
few of our witnesses believe that there is any close relation 
between the atmospheric pressure and the occurrence of colliery 
explosions ; more particularly some of the viewers from the 
north, who have closely watched these phenomena, are of opinion 
that such connection has not been made out.” It is, however, 
a fact, that South Wales is particularly unfortunate as regards 
explosions. Now the west coast is much exposed to constant 
atmospheric changes. This may be attributed to the prevailing 
winds being from the west and south-west, which are charged 
with the vapour of the Gulf Stream. When this moisture-laden 
atmosphere comes in contact with the hills of \^’ales, the moisture 
is precipitated, and at the same time latent heat is liberated. 
Therefore, though the actual falling of the barometer may 
not add to the danger, the rise of its colleague, the thermometer, 
may. 
It is, however, probable that both the atmospheric variations 
and coal dust are liable to facilitate explosions, and that the 
I Colliery Guardian, October 28, 1881, p. 709. 
