Lampas, or Descriptions of Mechanical Improvements of Lamps and Waterpoises

Those parts of the body of vapors original: "steams" that rise from the wick—which are in the middle and not in contact original: "contiguous" with the outer air—are not dissolved or turned into a shining flame by the air until they rise toward the top of the cone of flame. There, the free air can reach and dissolve them. Otherwise, by gathering around the wick in the center of the cone of flame, they choke, clog, and completely stifle it so that the flame quickly goes out. Anyone can easily verify this by examining the flame of a lamp or candle using a piece of glass. Because of the glass's transparency, you will plainly see that the entire middle of the cone of flame neither shines nor burns. Only the outer surface original: "Superficies", which is in contact with the free and unconsumed original: "unsatiated" air, does so. The middle parts can be collected in the form of soot or very fine powdered coal dust.

Take then a piece of glass—whether window glass, a mirror, or the side of a vial, it does not matter—or, best of all, a thin plate of selenite original: "Selenitis"; a transparent, colorless variety of gypsum. or muscovy glass original: "Muscovia Talk"; a type of mica used for windows and lanterns before glass became cheap and common.. Hold it horizontally in the middle of the flame so as to cut off the top or upper part of the cone. Then, immediately, before it becomes choked with soot, look down through it. You will plainly see that the middle parts of the flame and the wick have no shining power or light at all. They are not dissolved by the air but remain in the form of soot. Only the surface or outside of the cone burns, shines, and is consumed into and mixed with the surrounding original: "ambient" air.

In the same manner, if you hold the glass or selenite vertically and position it so as to cut through the flame through the axis of the cone original: "per axin coni"—preventing the air from reaching one side—you can clearly see that the shining part of the flame is only that which is in contact with and consumed by the free and unspent air. Where that air cannot reach freely without becoming exhausted original: "glutted and satiated" along its path, neither the consumption of the oil original: "Oyl" nor the heat and light of the flame is produced—only a sooty, choking, and stifling substance.