152

appendix:.

No. 4.

I have had some correspondence with Mr. Buddierespecting the accidents which have happened in coalmines, since the discovery of the Safety Lamp. Herefers them, in all cases, to the carelessness of workmen.

1 should strongly recommend double lamps, in caseswhere miners are obliged to work for any time in ex-plosive mixtures, or wherever currents are expected ;—or lamps with mica, or tin-plate within the wire gauzeto prevent too great a circulation of air, (see p. 138.)It is very easy to extinguish a lamp in which the fire-damp is burning, by sliding a tin-plate cylinder over it,or by a circle of wire gauze fitting the interior in a rimof copper and moved by the termination of the trimmingwire: but it is much better, in all cases of danger, touse lamps which, under' no circumstances, can explode.Such as these described in p. 97.

Having often trusted my life to the Safety Lampunder the most dangerous circumstances, I cannot butsometimes smile when the Public papers endeavour toinvalidate its security upon the opinions or evidence ofcertain persons who have their own nostrums for preven-ting the accumulation of inflammable air in mines.

I have sometimes to read letters on the improvementof the invention, by plans : most of which are discussedin the foregoing pages ; such as using glass or mica asa part of the surface for transmitting light, using doublelamps, or double lamps containing a reflecting surface