76 HISTORY OF 



ean see no visible mark of its pestilential va- 

 pour ; only, to about a foot from the bottom, the 

 wall seems to be tinged with a colour resembling 

 that which is given by stagnant waters. When 

 the dog, this poor philosophical martyr, as some 

 have called him, is held above this mark, he does 

 not seem to feel the smallest inconvenience ; but 

 when his head is thrust down lower, he struggles 

 to get free for a little ; but in the space of four 

 or five minutes he seems to lose all sensation, and 

 is taken out seemingly without life. Being plung- 

 ed in the neighbouring lake, he quickly recovers, 

 and is permitted to run home, seemingly without 

 the smallest injury. 



This vapour, which thus for a time suffocates, 

 is of the humid kind, as it extinguishes a torch, 

 and sullies a looking-glass ; but there are other 

 vapours perfectly inflammable, and that only re- 

 quire the approach of a candle to set them blaz- 

 ing. Of this kind was the burning well at Brose- 

 ly, which is now stopped up ; the vapour of which, 

 when a candle was brought within about a foot 

 of the surface of the water, caught flame like 

 spirit of wine, and continued blazing for several 

 hours after. Of this kind, also, are the perpetual 

 fires in the kingdom of Persia. In that province, 

 where the worshippers of fire hold their chief 

 mysteries, the whole surface of the earth, for 

 some extent, seems impregnated with inflammable 

 vapours. A reed stuck into the ground continues 

 to burn like a flambeau ; a hole made beneath the 

 surface of the earth, instantly becomes a furnace, 

 answering all the purposes of a culinary fire, 



