3855.) On the Ventilation of Coal-Mines. 417 
The most valuable discoveries are frequently of the greatest sim- 
plicity, and have occasionally been elicited by persons whose habits 
were very remote from the scene of their applicatiov. Will you 
rmit one, who is desirous of obtaining as much information as 
possible upon the methods at present adopted to ventilate coal- 
mines, to request that some of your correspondents who are con- 
versant with the subject would state in your Journal, or refer to any 
other publication, in which a minute detail may be found of the 
whole of the contrivances employed to expel, exhaust, or counteract, 
the injurious effects of the carbureted hydrogen gas, which has in 
so many instances rendered the extremities of mines inaccessible to 
the workmen. I am not unacquainted with the usual method or 
ventilation by the atmospheric current; but should, nevertheless, 
wish to see a circumstantial account of the different processes, 
common or rare, by which it is effected,.and where and in what 
respects they are found to fail, together with whatever expedients 
may have been resorted to as remedies for such defects ; and where 
these also have been unattended with success, to what cause such 
failures may be attributed. It would likewise be desirable to know 
héw far any of the ingenious persons interested and concerned in 
mines have proceeded in their endeavours to devise a security for 
miners against the effects of the eruption of gas while they are at 
work. 
A statement of the whole of these particulars, and of any others 
that bear upon the points in question, might prove of service to the 
cause, in calling forth the efforts of some, who, wishing to employ 
their thoughts upon them, are, for want previously of precise in- 
formation upon these matters, at a loss how to direct their attention 
to advantage. I need scarcely suggest that, in taking any subject 
of art into consideration, it is highly expedient to be informed of 
the advancement which others have already made in it, and the 
manner in which even their unsuccessful attempts have been 
directed. Where this cannot be obtained, invention will not have 
fair play, and the most sedulous endeavours may be lavished upon 
what has long been known. After a series of efforts, it has often 
appeared that only a small portion has been gained of the same 
ground, over which others had unprofitably passed before, and hours 
ef application may thus be utterly. lost. 
Jam, Sir, yours respectfully. 
Vor, VI. N° V1, 2D 
