THE SAFETY-LAMP. 289 



Davy to the subject, and that eminent chemist visited 

 the coal-mines in 1815 with the object of determining 

 what form of lamp would be best suited to meet the 

 requirements of the coal-miners. He invented two 

 forms of lamp before discovering the principle on 

 which the present safety-lamps are constructed. This 

 principle the property, namely, that flame will not 

 pass through small apertures had been, we believe, 

 discovered by Stephenson, the celebrated engineer, 

 some time before ; and a somewhat angry controversy 

 took place respecting Davy's claim to the honor of 

 having invented the safety-lamp. It seems admitted, 

 however, by universal consent, that Davy's discovery 

 of the property above referred to was made indepen- 

 dently, and also that he was the first to suggest the 

 idea of using wire-gauze in place of perforated tin. 



In comparing the present frequency of colliery ex- 

 plosions with what took place before the invention 

 of the safety-lamp, we must take into consideration 

 the enormous increase in the coal -trade since the 

 introduction of steam machinery. The number of 

 miners now engaged in our coal-mines is far in ex- 

 cess of the number employed in the beginning of the 

 present century. Thus accidents in the present day 

 are at once more common on account of the increased 

 rapidity with which the mines are worked, and when 

 they occur there are more sufferers ; so that the fre- 

 quency of colliery explosions in the opening years of 



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