FIRE AND LIGHT. 29 



paraffin oil lamps. Even our lighthouses used only 

 candles down to the early part of the present century. 



A far more important and more radical change in our 

 . modes of illumination was the introduction of gas-light- 

 ing. A few houses and factories were lighted with gas 

 at the very end of the last century, but its first applica- 

 tion to out-door or general purposes was in 1813, when 

 Westminster Bridge was illuminated by it, and so suc- 

 cessfully that its use rapidly spread to every town in the 

 kingdom, for lighting private houses as well as streets 

 and public buildings. When it was first proposed to 

 light -London with gas, Sir Humphrey Davy is said to 

 have declared it to be impracticable, both on account of 

 the enormous size of the needful gasholders, and the 

 great danger of explosions. These difficulties, have, 

 however, been overcome, as was the supposed insupera- 

 ble difficulty of carrying sufficient coal in the case of 

 steamships crossing the Atlantic, the impossibilities of 

 one generation becoming the realities of the next. 



Still more recent, and more completely new in prin- 

 ciple, is the electric light, which has already attained a 

 considerable extension for public and private illumina- 

 tion, while it is applicable to many purposes unattainable 

 by other kinds of light. Small incandescent lamps are 

 now used for examinations of the larynx and in den- 

 tistry, and a lamp has even been introduced into the 

 stomach by which the condition of that organ can be 

 examined. For this last purpose numerous ingenious 

 arrangements have to be made to prevent possible in- 

 jury, and by means of prisms at the bends of the tube 

 the operator can inspect the interior of the organ under 

 a brilliant light. Other internal organs have been ex- 



