On the Safe-lamp, and the Ventilation of Mines. 63 



ivater, to prevent the escape of the carbonic acid into the mine,' 

 I regret that this gentleman should have put me under the ne- 

 tessity of making tliese observations, and should have been bettei' 

 pleased had he satisfied himself with stating his own plans. 



" I am, sir, yours, &c. 

 " Edinburgh, Dec. 18, 1815. J. MuRRAY." 



Subsequent to this I was informed that I had been attacked 

 with much violence by this gentleman in some provincial news- 

 papers. These attacks I had no opportunity of seeing, nor did 

 I make any inquiry with regard to them ; and I only notice the 

 circumstance at present to say, that should any thing of this 

 kind appear in replvto this letter, I shall not consider it necessary 

 to pay any attention to it, 



I remain, sir, 



YoLir most obedient servant, 

 Edinburgh, Jan. 18, 1817. J. MuRRAY* 



XIV. On the Safe-lamp, and the Ventilation of Mines, 

 By Mr. J. Murray. 



To Mr. Tilloch. 



SiR, — In virtue of my promise 1 shall now advert^ and that 

 but briefly, to the methods I have proposed to the Society fo!* 

 Prevention of Accidents in Coal Mines, to aid the purposes of 

 ventilation. And here let me premise that I firmly believe the 

 present system of ventilation to be radicaUij defective: — so far as 

 it goes, it proceeds upon the well-known principle that aerial 

 fluids will flow towards the source of heat and rarefied medium : 

 but it ought to conjoin with this, a provision for the specific 

 gravities of those gases which the miner has to contend with; 

 namely, hydrocarbonate and carbonic acid gas. 



Towards this desideratum approximations have been made by 

 the ingenuity of Mr. Ryan and Mr. Menzies. It may be ques- 

 tioned, however, whether these ingenious plans can in every 

 case be made practically effective: — repeated and extensive dis- 

 locations would likelv render an insulation of the coal-field ex- 

 tremely difficult, if at all to be accomplished; and there are 

 other reasons which will readily present themselves to the re- 

 fleeting mind,— as the difficulty of determining tlie limits of the 

 strata, and the like. Add to this, elastic volumes cannot rest 

 upon each other, without mingling together; the liberated hydro- 

 carbonate would in the very act of ascent diffuse itself suffi- 

 ciently through the air of the mine to complete an exploitive 

 ini.xture. 



The 



