A SHIP ATTACKED Y A SWORD-FISH. 259 



lateral power, and might so wriggle its sword out of a 

 hole.' And so the insurance company will have to pay 

 nearly six hundred pounds because an ill-tempered 

 fish objected to be hooked, and took its revenge by 

 running full tilt against copper sheathing and oak 

 planking. 



(From the Daily News, December 11, 1868.) 



THE SAFETY-LAMP. 



As recent colliery explosions have attracted a con- 

 siderable amount of attention to the principle of the 

 safety-lamp, and questions have arisen respecting the 

 extent of the immunity which the action of this lamp 

 secures to the miner, it may be well for me briefly to 

 point out the true qualities of the lamp. 



In the Davy lamp a common oil-light is surrounded 

 by a cylinder of wire-gauze. When the air around 

 the lamp is pure the flame burns as usual, and the 

 only effect of the gauze is somewhat to diminish the 

 amount of light given out by the lamp. But so 

 soon as the air becomes loaded with the carburetted 

 hydrogen gas generated in the coal-strata, a change 

 takes place. The flame grows larger and less lumi- 

 nous. The reason of the change is this : The flame 

 is no longer fed by the oxygen of the air, but is 

 surrounded by an atmosphere which is partly in- 

 flammable; and the inflammable part of the gas, so 



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