THE CONQUEST OF NATURE 



that has been the means of saving thousands of lives, 

 and which has not as yet been entirely supplanted by any 

 modern invention. 



In making his numerous experiments, Davy had ob- 

 served that iron- wire gauze is such a good conductor 

 of heat that a flame enclosed in such gauze could not 

 pass readily through meshes to ignite a gas on the out- 

 side. He found by experiment that a considerable 

 quantity of explosive gas might be brought into contact 

 with the gauze surrounding a flame, and no explo- 

 sion occur. At the same time this gas would give 

 warning of its presence by changing the color of the 

 flame. When a lamp was made with a surrounding 

 gauze having seven hundred and eighty meshes to the 

 square inch, it was found to give sufficient light and 

 at the same time to be practically non-explosive in 

 the presence of ordinary quantities of gas. 



One would suppose that such a life-saving invention 

 would have been eagerly adopted by the men whose 

 lives it protected; but, as a matter of fact, owing to 

 certain inconveniences of Davy's lamps, many miners 

 refused to use them until forced to do so by the mine- 

 owners. One of these disadvantages was that this 

 safety lamp gave a poor light overhead. This is par- 

 ticularly annoying to the miner, who wishes always 

 to watch the condition of the ceiling under which he 

 is working. When not under constant observation, 

 therefore, a miner would frequently remove the gauze 

 of the lamp and work by the open flame, regardless 

 of consequences. Or again, he would sometimes for- 

 getfully use the flame for lighting his pipe. To over- 



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