52 Addillo7tal pracf'tcal Olservatiom on the 



most dangerous mines in England for nearly five months, during" 

 which time no accident has happened, and no inconvenience oc- 

 curred. 



Since I first published the account of the vvire-ganze safe-lamp, 

 I have made a nuniher of experiments on flame, which have led 

 ti> some new philosophical views of tliis curious and important 

 fuhject, and to some practical results, which I hope will be use- 

 ful to the miner : these last will form the subject of tiie follow- 

 ing pages. 



I lind that double cylinders of wire-gauze, so arranged that the 

 wires are parallel to each other, occasion verv little loss of light, 

 and very much diun'nish the heat when the fire damp alone is 

 burning within the cylinder ; so that with double cylinders I have 

 never observed the wire-gauze to become red hot. The double 

 cylinder lamp, therefore, is preferable to the single one, whenever 

 it is necessary to preserve a light for a long time in a highly ex- 

 plosive atmosphere, and it has likewise twice the strength of the 

 single cylinder lamp. 



If objections, which have been made, probably by persons who 

 had never seen the lamps, against the weakness of the wire, had 

 really been valid, it would be easy to double the thickness of it, 

 or to have treble, or even quadruple folds of wire, wich bars per- 

 fectly parallel. Layers of wire-gauze, for instance, of 25, 26, 

 and 27 apertures to the inch in the cylinder of the common size, 

 when arranged with a little care, intercept very little more light 

 than a single layer. 



I have had two lamps made of cylinders of copper perforated 

 with numerous small apertures ; but they are more expensive 

 than cylinders made of copper wire-gauze. 



I have had a lamp made of double wire-gauze with an exterior 

 copper chimney, which can be raised or lowered, so as to con- 

 sume larger or smaller quantities of fire-damp. This lamp, I find, 

 may be made to burn in a highly explosive atmosphere without 

 producing considerable heat, for any length of time ; and it offers 

 a convenient forn) of a lamp for destroying the fire damp. 



It does not appear, from Mr. Buddie's connnunications, that 

 the iron wire rwsts in common use : should this i)c found to be 

 the case in certain mines, copjjer wire may be used ; the addi- 

 tional expense of this material is trifling ; and even wire plated 

 with silver would not be so costly as to be an object in the price 

 of the lamp. In the double cylinder lamp, the copper wire will 

 never become red hot ; and I have had lamps made in which the 

 inner cylinder vvas of iron and the outer one of copper wire. 



Whenever a single wire lamp is made to burn in a very cxplo- 

 Rive atmosphere, the heat soon arrives at its maxiniimi, and then 

 diminishes; and the idea of the wires burning out, is, shown to 



lie 



