736 



SAFETY LAMP 



combustion. Upon the bars which protect the glass rests the gauze-cylinder above it. 

 When this lamp is first brought into an explosive mixture the flame is first lengthened, 

 and then extinguished. It unfortunately nappens that by turning the lamp on one 

 side the flame is often put out, and in the mines of Liege boys are employed to relight 

 the extinguished lamps. It is, however, stated that not less than 12,000 of these 

 lamps are in daily use in Belgium. 



Combe's and Boty's are modifications of the preceding. 



Parish's lamp, one by Dr. Fyfe, and some others by Mr. Hewitson and by Mr. 

 Biram, involve the use of mica in the place of glass. 



Eloin's lamp consists of a cylinder fixed upon the upper surface of the cistern 

 and the glass-shield, which is pierced with several holes covered with wire-gauze, 

 through which the air enters. As in Upton and Koberts's lamp, a cone assists the com- 

 bustion. A copper chimney is connected with the base, pierced in the upper end \vith 

 small holes, through which the products of combustion escape. The light is improved 

 by means of a reflector, which slides upon the bars, by which the glass is protected. 



Dr. Glover, Mr. Cail, and Mr. T. Y. Hall have introduced lamps which are so 

 similar to those already named that they need not be described. 



Mackworth's safety lamp was contrived by one of the Government Inspectors 

 of Coal-mines, to meet the objections raised in resisting the general introduction of the 

 Davy lamp into fire-damp mines. As the lamp is not used, it need not be described. 



Some other lamps have been brought forward, the chief purpose being to prevent 

 their being opened by the miner. Mr. W. P. Struve, of Swansea, constructed an in- 

 genious safety lamp. The sketch,^. 1744, will convey a better notion of it than any 



1744 



1745 



1746 



written description ; and it is only necessary to add, that although the diameter of 

 the gauze-cylinder at its base is considerably more than that of the Davy, yet owing 

 to the oil-box being placed within the gauze-cylinder, instead of below it, and thus 

 occupying a considerable portion of the internal space, the cubical contents of the 

 cylinder do not exceed that of an ordinary Davy. The greater amount of cooling 

 surface near the flame, and the less-obstructed admission of air thus obtained, renders 

 it practicable and perfectly safe to use a larger wick than in the Davy, whilst the 

 combustion of the oil is much more perfect, and the smoke very considerably diminished. 

 The light emitted from this lamp has been carefully ascertained to be equal to that 

 from three Davys ; and, owing to the conical form of the cylinder, and the shape of 

 the oil-box, it difiuses the light both upwards and downwards, as well as in every 

 other direction, with less shadow than any other lamp that has been offered to the 

 miner. From the more perfect combustion, the consumption of oil in this lamp but 

 slightly exceeds that of the Davy, while its simplicity of construction gives great 

 facilities for keeping it in order and for repairs. It barely weighs l Ib. 



