A few additional practical observations on the wire-gauze safety-lamps for miners : with some evidence of their use / [by Sir Humphry Davy].

  • Davy, Humphry, Sir, 1778-1829.
Date:
1816
Catalogue details

Licence: Public Domain Mark

Credit: A few additional practical observations on the wire-gauze safety-lamps for miners : with some evidence of their use / [by Sir Humphry Davy]. Source: Wellcome Collection.

    11/42 (page 5)
    'Vitreous incombustible composition might be used as a coating to prevent the rusting of the wire, and I made some experi- ments on this subject. I lind that a fusible compound of boracic acid and the earth called baryta, answers the purpose of a coating very well; and if in any case experience should prove that such an application is necessary, it may be easily made. It is obvious, that as long as the principle of security (which is to admit no aperture in a lamp of more than inch s,quare) is preserved, the construction may be almost infinitely varied, and the fire-damp may be burned throughout the whole of a cylinder, or inflamed at certain surfaces only, and the light transmitted from other surfaces thrmT^h Uuiix, or-' mica, or glass. I long ago had a lamp made of glass, in which the fire damp burnt round the wick only, from a circular sur- face of wire-gauze, and which, in an explosive mixture, produced very little more heat than in the common atmo- sphere ; but the facility with which glass is broken, and horn and mica injured, prevents me from recommending any lamps in which these substances are used for the common purposes of the miner. I have tried a chimney of brass capped with a double wire- gauze cylinder, having fwo-thirds of its circumference opposite the flame open, and covered with wire-gauze. This, in an explosive mixture, produced very little heat, tliough it gave a tolerable light, and by increasing the surfaces impermeable, or by diminishing those permeable to air, the heat may be reduced in any degree.* Whatever construction is adopted, too much attention cannot be paid to the form of the screw by which the cylinder * The Rev. John Hodgson, whose zeal and activity in promoting the objects of these researches I cannot praise too highly, has had a lamp made upon this plan, having a thick plate of glass in a metal- lic chimney opposite a wire-gauze feeder, in which the supply of air is regulated by means of a slider. I found a model which he sent me to answer very well; the only objection is, the chance of the glass being broken by a fall, or by a drop of w'ater when hoi,