53. A self-trimming Lamp.
To contrive a self-trimming lamp. Let A B C (fig. 33), be a lamp through the mouth of which is inserted an iron bar, D E, capable of sliding freely about the point E, and let the wick be wound loosely about the bar. Place near a toothed wheel F, moving freely about an axis, its teeth in contact with the iron bar, that, as the wheel revolves, the wick may be pushed on by means of the teeth. Let the opening for the oil be of considerable width, and when the oil is poured in let a small basin float upon it, G, to which is attached a perpendicular toothed bar, H, the teeth of which fit into the teeth of the wheel. It will be found that, as the oil is consumed, the basin sinks and causes the wheel F to revolve by means of the teeth of the bar, and thus the wick is pushed on.