swinging, C, and the further end of it is chilled by dipping it into cold water. A workman then, having prepared a disk of hot Glass, D, called a post, places it vertically as near the ground as possible, to receive the ball from the chief workman; he next ascends his chair, or an elevation, so that the hot Glass may by its gravity be dropped upon the post below, to which it adheres by partial welding, E. The chief workman then descends from his elevation; the drawing now begins—each workman constantly receding from the other: at first, the suspended Glass between the two rods assumes (at a red heat) the form of a parabola, F; but, as the tension proceeds, the workmen are continually rotating. Some parts are cooled by fanning with the hat of an attendant boy, to ensure uniform elongation, till the cane or tube is drawn to a length, sometimes of from sixty to seventy feet; as the metal cools, the tube ceases to rotate, and it assumes, by continued tension, nearly a straight line, G; except at the extreme ends, it is