of lighting the Mines so as to prevciit its Explosion, 457 



Fig. 4. exhibits the safety concentric canals or fire sieves, 

 which, if -j'- of an inch in diameter, must not be less than 2 

 inches in exterior circumference, and 1.7 inches high. 



Fig. 5. exhibits the longitudinal safe canals or fire sieves. 



Fig. 6. exhibits a safe lamp, having a glass chimney covered 

 with tin-plate, and the safety apertures in a cylinder with a 

 covering above : the lower part is the same as in the lantern. 



Fig. 7. An Argand lamp of similar construction, with safe 

 air canals without the flame, and metallic gauze apertures 

 within. 



Fig. S. A tin-plate chimney top for the lamp, made safe by 

 metallic gauze. 



Fig. 9, A metallic gauze safe lamp. AAA. Screens of 

 metallic gauze or j?«m(? sieves. BB, Wires for trimming the 

 wick. 



Fig. 10. A glass tube furnished with flame sieves, in which 

 a common candle may lie burnt. AA. The flame sieves. B. A 

 little plate of metal to prevent the upper flame sieve from being 

 acted on bv the current of hot air. 



The lamps burn brighter the higher the chimney. 



From my experiments it appears, that a mere narrow throat 

 and opening to the metallic part of the chimney, is sufficient to 

 prevent explosions from passing through the lamp, supposing 

 them possible ; but with the safety canals or metallic gauze in 

 the chimney the security is absolute. 



The circular canals and the apertures covered with metalliu 

 gauze, are so much superior to tubes in practical ajjplication, 

 that I have no doubt of their being generally used ; I have 

 therefore given no sketch of the first safo lantern I had con- 

 structed with tubes ; but substituting tubes for canals it is ex- 

 actly tlie same as that represented fig, 1. 



Appendix. 



1. In the beginning of my inquiries I had an.other close lantern 

 made, which may be called the fire-valve i:uiLern. lathis, the 

 candle or lamp burns witli its full quantity of air, admitted from 

 an aperture below, till the air begins to be mixed with fire- 

 damp ; when, as the fire-damp increases the flame, a thermo- 

 metrical spring at the top of the lanterji, made of brass and 

 steel, riveted together, and in a curved form, expands, moves 

 a valve in the chimney, diminishes the circulation of air, and 

 extinguishes the flame. But I did not pursue this invention 

 after I had discovered the properties of the fire-damp, on which 

 the safe bnitern is founded. 



2. The safety of close lamps or lanterns may probably be like- 

 wise secured by sieves made of asbestus, or possibly even hair 



or 



