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carried about by the miners, iron wire-gauze’ I have no doubt, will be the material al-ways employed.-—I have tried a lamp onthe plan of Argand’s, in which wire-gauzefeeders were below, and in which a currentof air was determined by wire-gauze cylin-ders above; it gave a brilliant light, butproduced so much heat as to boil the oil inthe reservoir, and it required a complicatedcontrivance for trimming it.

When a cage of wire of platinum isused within a lamp, even where the ex-plosive mixture burns with flame, itdiminishes the heat by its radiation, andit increases the light, so that it will alwaysbe useful in lamps; and as it is an impe-rishable metal, it is only the original ex-pence, which is very small, that is to be at-tended to. It is proper to urge again whathas been mentioned, page 112, that no wireor filament of platinum must be suffered toproject beyond the wire-gauze, so as to bein the external atmosphere.

The forms of lamps may be infinitely va-ried; but the most convenient size for acommon working lamp is from eight to teninches in height, and two to two and a half