It is very easy to make a glass machine of the cylindrical form, if the maker cannot afford to buy one. First procure a common wine bottle of good dimensions, and thickish glass. Drill a hole through its bottom, with a file moistened with dilute sulphuric acid. A blacksmith, if supplied with the acid, would undertake to do this part of the work. Through this hole and the mouth pass a spindle, as represented in the [cut]. The end of B should be squared to fix a handle on, and the spindle should be fixed firmly in the bottle. The bottle is then to be fixed in a frame in the [following manner]: the end of the spindle C passes through a hole at B; and the other end at C has the handle for turning the machine.
Next make a cushion of wash-leather stuffed with wool, and fastened to the top of a frame of the following [figure]. This frame is to be of such a height that the cushion shall press against the sides of the bottle, and a piece of black silk is sewn on to the top of the cushion, and hangs over the bottle D. The cushion should be smeared with an amalgam, formed by melting together in the bowl of a tobacco-pipe one part of tin with two of zinc; to which, while fluid, should be added six parts of mercury. These should be stirred about till quite cold, and then reduced to a fine powder in a mortar, and mixed with a sufficient quantity of lard to form a thickish paste. When all is done, the machine is complete.
CUSHION.