112 IMPKOVES HIS LAMP. CHAP. VII. 



sion of the gas. Returning 1 to his companions, who 

 were still at a distance, he told them what had occurred. 

 Having now acquired somewhat more confidence, they 

 advanced with him to a point from which they could 

 observe him repeat his experiment, but still at a safe 

 distance. They saw that when the lighted lamp was 

 held within the explosive mixture, there was a great 

 flame ; the lamp was almost full of fire ; and then it 

 smothered out. Again returning to his companions, he 

 relighted the lamp, and repeated the experiment. This 

 he did several times, with the same result. At length 

 Wood and Moodie ventured to advance close to the 

 fouled part of the pit ; and, in making some of the later 

 trials, Mr. Wood himself held up the lighted lamp to 

 the blower. Such was the result of the first experi- 

 ments with the first practical Miner s Safety- Lamp ; and 

 such the daring resolution of its inventor in testing its 

 qualities. 



Before leaving the pit, Stephenson expressed his 

 opinion that, by an alteration of the lamp, which he 

 then contemplated, he could make it burn better. This 

 was by a change in the slide through which the air was 

 admitted into the lower part of the lamp, under the 

 flame. After making some experiments on the air 

 collected at the blower, by means of bladders which 

 were mounted with tubes of various diameters, he satis- 

 fied himself that, when the tube was reduced to a 

 certain diameter, the explosion would not pass through ; 

 and he fashioned his slide accordingly, reducing the 

 diameter of the tube until he conceived it was quite 

 safe. In the course of about a fortnight the experi- 

 ments were repeated in the pit, in a place purposely 

 made foul as before. On this occasion a larger number 

 of persons ventured to witness the experiments, which 

 again proved successful. The lamp was not yet, how- 

 ever, so efficient as the inventor desired. It required, 

 he observed, to be kept very steady when burning in 



