INGENUITY AND LUXURY 



back to the open furnace so as to soften the end. When 

 it is sufficiently hot it is pierced with an open point. 

 By the balancing movement* this opening is increased ; 

 the glass is pared with a sort of wooden plate; the 

 edges separate and the top of the cylinder disappears. 

 "When the cylinder has become firm, it is placed 

 on a wooden rest. The end of the pipe is touched 

 with a cold rod; it separates immediately from the 

 cylinder, which has already lost its bullion point, 

 when a thread of hot glass is wound around it, 

 and the part thus heated is touched with a cold 

 iron rod. Thus we have now on the rest a cylinder 

 open at each end. It is opened by passing a red-hot 

 iron rod down the interior in a straight line ; one of the 

 heated extremities being wetted with the finger, the 

 glass bursts open. The same result may be obtained 

 by using a diamond attached to a long handle, which 

 is passed down the interior of the cylinder by the side 

 of a wooden ruler. This method gives a straighter 

 cut, and consequently involves less loss." 



Each of these cylinders is to form a perfectly flat 

 pane of glass, for which purpose it must be heated in 

 the flattening-oven. In this oven it is placed on a 

 flat slab, whicl is covered with some such substance 

 as gypsum to present adhesion. The natural effect of 

 the heat is to cause the cylinder to unroll, a workman 

 assisting this process by gentle pressure with a pole. 

 When it has become completely flattened the ovens 

 are hermetically sealed, and the annealing process, 

 which will be explained in a moment, begins. 



[290] 



