DURHAM AND NORTHUMBERLAND. 109

EXPLANATION OF PLATE VII.

Fig. 1 represents Sir H. Davy’s lamp, withthe air feeder and chimney, furnished withthe concentric metallic canals, and is made tocontain nearly one quart of air : the sides areof horn or glass made air-fight; and at thetop is a hollow cylinder covered with a cap toprevent dust from getting into the lantern.

Fig. 2 represents a lamp upon the same prin-ciple as fig. 1, with concentric metallic airfeeders at the bottom, and a glass chimney withsimilar canals in the top, and covered with atin plate. An Argand lamp may be used inthis way; and if the apparatus is furnishedwith metallic gauze sieves in the chimney, thesecurity is more certain.

Fig. 3, a metallic gauze lamp, with screensof wire gauze, and so constructed that the wickmay be trimmed without inconvenience.

Sir H. Davy had some glass tubes con-structed with metallic gauze feeders, in whicha common candle may be burnt; but there isno doubt of many practical alterations in hisas well as other lamps: and as some of themrequire the test of application, it would be su-perfluous to describe the numerous differentmethods in which these principles, as well asthose of other lamps, might be used. I shall