22 Sir Humphry Davy on the fire-damp of coal mines, &c. 
APPENDIX, 
«* 
1 In the beginning of nay inquiries I had another close lantern 
made, which may be called the fire-valve lantern. In this, the can- 
dle or lamp burns with 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 thermometrical 
spring at the top of the lantern, 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 1 had discovered the 
properties of the fire-damp, on which the safe lantern is founded. 
2. The safety of close lamps or lanterns may probably be likewise 
secured by sieves made of asbestus, or possibly even hair or silk, 
placed over the air apertures : but metallic gauze will be necessary 
above in the chimney. I have little doubt but that windows of 
fine metallic gauze may be used for giving light in lanterns, with 
perfect security ; perhaps for the chimney it may be worth while to 
have fine silver plated wire gauze made. 
3. The expansive powers of the fire-damp during its explosion, 
are so small as to render no precautions, with respect to the thick- 
ness of the glass or horn in the lamps or lanterns, necessary. 
