from Flre-danip in Mines i 6 



forminsj an insulated atmosphere round the flame of a lamp 

 or a candle; admitting the air of the mine thereto in such 

 proportion, and so diluted with the insulated and incom- 

 bustible air, as to prevent explosion. 



This last plan has often been proposed ; and I under- 

 stand that a gentleman of Sunderland has completed a 

 contrivance of this kind. Although these modes of ob- 

 taining the end in view are in a great measure free from 

 the difficulties inseparable from reagents, yet there are 

 others which render them also objectionable. 



With regard to the first method, the only one with which 

 I am acquainted is the steel mill as it is called, which 

 consists of a number of flints, so placed with respect to a 

 circular steel pulley or wheel, to which a handle is fixed, 

 that, when it is turned, a considerable quantity of light is 

 given out. The manual labour attendant on this plan, to- 

 gether with the expense of renewing the apparatus, (to say 

 nothing of the imperfect light procured,) renders it inappli- 

 cable to ordinary purposes. Indeed I believe it is seldom 

 or ever used_, except in peculiar situations, when a part of 

 the mine is incapable of v^entilation, without great expense 

 or difliculty. Moreover, it cannot be considered as entirely 

 free from danger of exploding the gas; and that this has 

 actually happened, I am well informed. 



Reflectors are sometimes used to convey light, in thril" 

 ling (or thurling) between two shafts of no great depth, 

 or for other works of a like nature, where the quantity of 

 fire- damp is considerable, and incapable of being carried 

 off with facility. 



Concerning lamps constructed so as to burn in an insu- 

 lated atmosphere, nothing deduced from practice can be 

 said. They must necessarily be expensive, and extremely 

 liable to be broken by pieces of coal, &:c., flying from the 

 workmen, or from accidental falls; and should this happen 

 in a part of the mine where the gas was accumulated in a 

 quantity suflBcient to render the use of such a lamp neces- 

 sary, what would be the consequence? Besides, compli- 

 cated machinery is ill calculated for ignorant and careless 

 miners: an instrument of this, nature must needs require 

 nice adjustment and frequent trimming, which last could 

 not be done with perfect safety where any danger was to be 

 apprehended. In short, men who have ever been accus- 

 tomed to the use of a candle, and a piece of clay as the 

 ready means. of fixing it where circumstances require, will 

 not willingly be incumbered with a lamp, even of a com- 

 mon construction. There is another serious objection to 



A3 be 



