gathering has cooled sufficiently, the gatherer proceeds to take up the second gathering upon it. The pipe is again introduced into the furnace and gradually dipped into the molten glass, but this must be done with great care so as to avoid the inclusion of air-bells between the glass already on the pipe and the new layer of hotter glass that is now taken up. This freedom from air-bells is secured by a skilful gatherer by a gradual rotation of the pipe as it is lowered into the glass, thus allowing the two layers of glass to come into contact with a sort of rolling motion that allows the air time to escape. When completely immersed, the pipe is rotated a few times and is then withdrawn and the “thread” again cut off. The mass of glass on the end of the pipe is now considerably larger than before and requires more careful manipulation to cause it to retain the proper, nearly spherical, shape. During the cooling process which now follows the pipe is laid across an iron trough, kept brimful of water; this serves to cool the pipe itself, and also allows the pipe to be readily rotated backwards and forwards by rolling it a little way along the trough. When the whole mass of glass has again cooled sufficiently to be manipulated without risk of rapid deformation, a third gathering of glass is taken up, in precisely the same manner as that already described for the second gathering, and if the quantity of glass required is large, or the glass itself is so hot and fluid that only a comparatively small weight adheres at each time of gathering, the process may be repeated a fourth or even a fifth time, but as the weight of pipe and adhering glass increases with each gathering, each step becomes more laborious, while the hot glass, being now held on a much larger sphere, tends to flow off more readily, so that greater skill is required to avoid “losing” the gathering. The care and skill with which these operations of gathering are carried out determine, to a large extent, the quality of the resulting sheet of glass; any want of regularity in the shape of the gathering leads inevitably to variations of thickness in different parts of the sheet, while careless gathering will introduce bubbles or “blisters” and other markings. During the intermediate cooling stages the glass must be protected from dust and dirt of all kinds, since minute specks falling upon the hot glass give rise to an evolution of minute gas bubbles which become painfully evident in the sorting room.