On Sir H. Davy's Safe- lamp for Mines. 195 



be lield vertically; at least I made repeated attempts to produce 

 an explosion with the lamp in that position, the gas being 

 thrown into it in tlie free atmosphere in vain, although I kept 

 the whole cylinder a considerable time completely filled with 

 t;ame, and the powdered m.ixtnre constantly projected into it ; 

 but when inclined, I succeeded. A mixture of gunpowder with 

 the coal was however necessarv ; without it I could obtain no ex- 

 plosion, nor with it could I alwavs succeed ; 7iever, indeed, till 

 after the gas had been thrown in iong enough to heat the wire 

 very hot ; but, — and it proves the accuracy of the reasoning on 

 the experiment, — when once an explosion was effected, it might 

 be repeated at pleasure, provided the gauze cylinder was not 

 suffered to cool. With the double lamps 1 could not by any 

 means produce an explosion, whatever position it was held in. 



1 placed coal-dust and gunpowder on the top of the wire- 

 gauze cylinder suspended in the lanthorn, and threw in the coaI» 

 gas. The whole cylinder was filled with flame, and the upper 

 part became red hot. The mixture burned, and threw off sparks, 

 but occasioned no explosion. On putting a lighted match into 

 the lanthorn the gas inunediately exploded with violence. 



The same exjjeriment was repeated with the addition of a jet 

 of atmospheric air thrown from a l)ladder with a small blowi- 

 pipe on the ignited coal and powder dust — but neither in thi? 

 case did any explosion ensue. 



A few words more, and I have done. Mr. Holmes seems in- 

 clined to hint that Sir Humphry Davy has borrowed the idea of 

 his lamp from Stevenson^s, and talks of the " ullerntion" he has 

 made on it, " by weaving the holes instead of having them 

 punched." If Mr. Holmes were acquainted with the progress 

 of the investigation by which Sir llum])hrv was led, step by step, 

 from successively established facts to the present perfection of 

 the instrument, he woidd know that Sir H. borrowed no idea 

 concerning it from Mr. Stevenson or any one else. It was early 

 in last October that Sir Iluui])!iry connnunicated in confidence 

 to me the discovery of the principle which was the base of his 

 sul^equent rea^sonings, viz. the narrow liu^its in which the pro- 

 portions of atmospheric air and fire-damp can be combined so 

 as to afford an explosive mixture; — ami on the following day 

 lie showed Mr. Brande and myself the experiments which con^- 

 firmed its accuracy. Like every thing else that Sir Humphry 

 lias done, this lamp is the result of consequences most sagaciously 

 deduced from causes most ingeniou'^ly and diligentlv inquired 

 into ; — and is it to be borne, that the labours of such a man are 

 to be made the su!)jict for every envious caviller to vent his spleen 

 on? or that it should be insinuated, tliat their results are pla- 

 giarisms and pilferings, from the accidental (however happy) dis- 

 N 2 V-overv 



