Lampas, or Descriptions of Mechanical Improvements of Lamps and Waterpoises

...is continually and evenly supplied to the flame of the lamp by the raising of the receptacle at the same rate the oil is consumed original: "wasts", so as to keep the surface original: "Superficies" of the oil always on the same horizontal plane. The receptacle is raised by a counterweight original: "Counterpoise" hung upon a fusee original: "Fusey"; a cone-shaped pulley used to regulate force, which fusee is part of an Archimedean spiral.

In the seventh figure, let CC represent the receptacle for the oil, being a cylindrical or prism-shaped vessel of whatever size or length you wish. Using two brackets original: "Ears" at LL, fasten two lines or ropes, KK, the ends of both being fastened to the wheel or pulley G, though one of them runs over the pulley F. A cylindrical or prism-shaped plug, AA, is fitted into this receptacle and fixed in a convenient place so that it does not rise or sink. Through the middle of this plug passes a siphon, BBB, one end of which extends like the branch of a candle or lamp to support the socket, D, for the flame, E. This flame is fed with oil through the siphon, BBB, as the receptacle, CC, rises.

A fusee, H, is fastened to the side of the pulley G. This must be made with very great care from one revolution of an Archimedean spiral, beginning not from the center, but from a suitable distance from it. At this starting point, the hanging weight, I, should exactly balance the receptacle, CC, when it is completely empty of oil. The other hanging counterweight (positioned at the widest part of this spiral) must be at such a distance from the center of the wheel G that the same weight, I, exactly balances the receptacle when it is filled to the top with oil. The fusee must be filed accurately to a spiral shape, drawn with great care for one revolution between those two points.

I specify "one revolution" here because I have assumed the wheel or pulley, G, is large enough that one revolution will lift the receptacle the entire distance it needs to be raised. If the pulley is so small that it requires two, three, four, or more revolutions, then the section of the spiral between those points must be drawn with two, three, four, or more revolutions proportionately, which...