Inspections of Wtre-gmtze Lamps. 199 



A brass pipe was now fixed upon the blower tube, so as to make 

 the whole stream pass through an aperture of less tlian half an 

 incli in diameter, which of course formed a most powerful blow- 

 ]Mpe, from which the fire damp, when inflamed, issued with great 

 violence and a roaring noise, making an intense flame of the 

 length of five feet. The blowpipe was exposed at right angles 

 to a strong wind, and the double gauze lamps and single lamps 

 successively placed in it. The double gauze lamps soon became 

 red hot at the point of action of the two currents ; but the wire 

 did not burn, nor did it comnuniicate explosion. The single 

 gauze lamp did not communicate explosion, as long as it was red 

 hot and slowly moved through the currents; but when it was 

 fixed at the point of most intense combustion, it reached a weld- 

 ing heat, the iron wire began to burn with sparks, and the explo- 

 sion then passed. 



In a second and third set of experiments on this violent blow- 

 pipe of fire-damp, single lamps, with slips of tin-plate on the out- 

 side or in the inside, to prevent the free passage of the current, 

 and double lamps, were exposed to all the circumstances of the 

 blast, both in the open air and in an engine-house where the 

 atmosphere was explosive to a great extent roimd the pipe^ and 

 through which there was a strong current of atmospheric air ; 

 but the heat of the wire never approached near the point at which 

 iron wire burns, and the explosion could never be communicated. 

 The flame of the fire-damp flickered and roared in the lamps, but 

 did not escape from its prison. 



There is no reason ever to expect a blow-pipe of this kind in a 

 mine ; but, if it should occur, the mode of facing it and examin- 

 ing it. with most perfect security, is shown ; and the lamp oflfers 

 a resource, which can never exist in a steel-mill, the sparks of 

 which would undoubtedly inflame a current of this kind. 



Arguments have been stated as to the weakness of the lamps. 

 In a board or gallery in the Wallsend colliery, Mr. Buddie and 

 myself, with some of the viewers, endeavoured to injure a single- 

 gauze lamp by throwing large pieces of coals upon it, and striking 

 it with a pick; but we never perforated the gauze; and the lamp, 

 after these severe trials, burnt with perfect security in a small ex- 

 plosive atmosphere made by Mr. Buddie at the bottom of the 

 shaft for the purpose of trying the lamps. 



I made with Mr. liuddle and his viewers some experiments on 

 the comparative light of the lamps, the common miner's candle, 

 and the steel niills, in a gallery in the Wallsend colliery. We 

 judged of the intensity of tiie lii;ht by the square of the distance 

 at which a small object was visible ; and made repeated trials on 

 each species of light. 



N4 The 



