a steady Light in Coal Mines, 203 



mable air, from accidental circumstances, that it would be im- 

 possible at all times to ascertain, by a chemical process, at all 

 parts of the mine, when danger is impending, for frequently 

 the greatest differences of proportions exist at the same time, 

 in different parts of such extensive works as coal mines. In 

 fact, the miners know, from the appearance of the light of 

 their candles, when the proportion of hydrogen gas is such, 

 as to threaten an explosion ; hence they carefully watch each 

 other's candles, that they may desist in time, and escape instant 

 destruction. 



The excavations of coal mines are much greater than they 

 are generally supposed to be : in some collieries they are con- 

 tinued for many miles, forming numerous windings and turn- 

 ings, along which the pit-men have frequently to walk for 

 forty or fifty minutes before they arrive at the workings y during 

 which time, as well as when at work, they have no direct 

 communication with the surface of the earth, but are entirely 

 at the mercy of their greatest enemy, the inflammable air. 

 This circumstance first impressed me with the idea that the 

 light, by which the pit-men were to work, might be insulated. 

 I was well aware that no preparation of phosphorus could 

 supply a sufficient light for the purpose; an observation equally 

 applicable to the miserable scintillations of steel mills (as they 

 are termed), which have often exploded the inflammable air 

 of the coal mines. 



I find it needful here to remark, that, as far as applies to my- 

 self, the idea of insulating the light, and also the plan which I 

 have adopted for carrying tnis idea ^nto effect, by the con- 

 struction of the apparatus or Jamp, are perfectly original. 

 This lamp may be managed vvith the greatest ease by apy 



MDCccxiii. E e 



