🚀 go-pugleaf

>     At one time I was informed that early coal miners used candles on 
>their helmets to provide light in the mines.  This would cause an 
>explosion now and them because of coal gas build-up.  Someone 
>discovered that by putting a metal cage around the flame, the candle 
>could be safely used in the mine.
>     Does anybody know whether or not this is true, who discovered it 
>and why it works?
>Chris Johnson
>Northeastern University

I'm 'F'ing instead of 'r'ing beacuse I don't think your return path
will work. 
I dimly recall from school that the lamp was called a 'Davies safety Lamp',
presumably invented by Davies (!). It worked, I think, on the principle
that the metal shield would conduct heat well enought to prevent the
flame front of the burning bas from getting through the shield. The lamp 
also worked as a coal gas indicator - when there was coal gas present,
the candle flame had a blue (I think) aura.
patrick
{ihnp4, hplabs, amdcad, ucbvax!dual}!fortune!stirling