The illustration (fig. 887) represents an ingenious arrangement, which, by means of combustion of oil in a lamp, indicates the hour of the night. The design explains itself. Two vertical tubes are fixed above the reservoir of oil. The left tube contains oil, and is marked with the hours; the right tube burns the oil as a lamp.
The apparatus is so constructed by the inventor, M. H. Behn, that a certain quantity of oil is consumed exactly in one hour between two graduations of the hour-tube. A reflector placed beside the lamp enables one to see the time by night very plainly.
An “Alarum” Lamp.
Fig. 888.—An “alarum” lamp.
The apparatus represented below (fig. 888) is an ordinary “alarum” lamp. It is surmounted by a petroleum lamp, which carries a burner that remains lighted all night, and which serves as a night-light. The “alarum” carries an index, represented by the dotted lines in the illustration, and the hands are fixed (with the index) to the hour you wish to rise in the morning. The index is fitted with an arrangement which lets loose a vertical bar represented on the right of the figure. This bar is held by a spring, and carries a toothed rack which acts upon and raises the wick. At the proper time the bar is loosed, and the lamp-wick is raised, diffusing a strong and sudden light through the apartment. This illumination, in concert with an alarum-bell, generally succeeds in awaking the heaviest sleeper.
A Good Petroleum Lamp.
This lamp (fig. 889) burns gazoline without the least odour or danger of explosion. It will serve equally well for petroleum or naphtha. The gazoline used ought to be 660 grammes weight to the litre.
