I'JH On tJie Fentilation of Coal-Minss. [March. 



fatherless cliildren ; and this in the same spot where about eighteen 

 months ago about 100 men were destroyed in a similar way. Nor 

 should I probably have ventured to press a consideration of the 

 sul)ject, had I not been strengthened in an opinion vvhich 1 ven- 

 tured to give, in the paper to which 1 have referred ; that my 

 engine might be applied to collieries with effect, by the weight of 

 your authority in some remarks of your own subjoined to the 

 account of the former accident. 



You have there shown that explosion cannot take place unless the 

 carbureted hydrogen amounts to a certain proportion of the whole 

 bulk of air, and that safety will be insured if the fire-damp could 

 be withdrawn so as to prevent accumulation to more than a certain 

 extent : and you suggest that some means might be devised for 

 pumping it out as it is produced. 



I beg leave to trouble you with an extract or two from the paper 

 above alluded to, as containing my opinion at the time it was 

 ■written, wliich opinion has been strongly confirmed by your obser- 

 vations on the subject. 



" The size of the exhauster may always be proportioned to the 

 demand for air ; and by a due consideration of this circumstance, 

 this engine may be effectually adapted, not only to mines and col- 

 lieries, but also to manufactories, workhouses, hospitals, prisons, 

 ships, &c. 



" Not being practically acquainted with 



collieries, or mines, that suffer from peculiar gases that are pro- 

 duced in them, I cannot state from actual experiment what effect 

 this machine miglit have in relieving them ; but it must appear, I 

 conceive, evident to every person at all acquainted with the first 

 principles of pneumatics, that it must do all that can be wished, as 

 it is obvious that such a machine must in a given time pump out 

 the whole volume of air contained in a given space, and thus 

 change an impure atmosphere for a better one. And in construct- 

 ing the machine it is only necessary to estimate the volume of gas 

 produced hi a certain time, or the capacity of the whole space to be 

 ventilated. 



" With such a machine as tliis, if the dreadful 



effects of explosions of this air (fire-damp) are to be counteracted, 

 it may be done by one of sufncient size to draw off this air as fast as 

 it is generated, and by carrying the pipes into the elevated parts of 

 the mine, where from its lightness it would collect." 



These hints, I venture to think, fall in very nearly with what 

 you have suggested; and my experience leaves no doubt on my 

 mind that the object may be attained, by employing either my 

 machine, or s"ome better one producing a similar effect. 



There is, I tliink, a strong reason why an apparatus of this sort 

 may be more effectual in a colliery than Tiny general system of ven- 

 tilation by shafts, drifts, and currents of air. 



A peculiar gas such as produces the destructive eflects we hear of 



