120 On the Manufacture of Glass. 



block of wood, which contains a small quantity of water, 

 where the blower causes it to rotate for a moment to give form 

 to the mass. Then applying the mouth piece of the pipe 

 to hie lips, and blowing, he gradually inflates the ball, still 

 continuing the rotation until it becomes of the required size. 

 This process forms a hollow globe on the upper side of the 

 ball. The workman now puts it again to the ring of the 

 furnace that it may regain the heat which it has lost in the 

 preceding process — it is then taken from the fire, and the pipe 

 again applied to the mouth, and standing on a bench, the blow- 

 er at one and the same time swings it from side to side, gives it 

 a rotatory motion, and inflates it. In this operation the centri- 

 fugal force, aided and corrected by gravitation, (while at the 

 same time it is inflated) causes the globe to assume the form 

 of a cylinder, attached to the pipe at one end, and closed by a 

 hollow hemisphere at the other. The cylinder is now held near 

 the ring, so as to soften the extreme ends, a hole is blown 

 through its centre, and then as it is rapidly whirled, the centri- 

 fugal force acting upon the softened hemisphere, converts it 

 in the first place into a plane, extending across the cylinder 

 at right angles with its sides, and then as the motion is con- 

 tinued, the central perforation increases in size until it sud- 

 denly expands to the diameter of the other parts of the cyl- 

 inder. It is then held perpendicularly a few moments until 

 the glass cools, when it is given to the boy, who, taking it to 

 a wooden support, cracks it from the pipe, by touching the 

 neck with a moistened iron. One other operation is required 

 to complete the cylinder which is called cappling. This is 

 done by taking from the pot a small quantity of the fluid 

 glass on an iron rod, and with the assistance of a pair of 

 pincers, it is applied around that end of the cold cylinder that 

 was attached to the pipe. This ignited thread, coming in 

 contact with the unannealed cool glass cracks the cap oflf, 

 leaving a perfect cylinder. To fit the cylinders for flattening, 

 an ignited iron is drawn repeatedly from end to end, when 

 withdrawing it, and applying the" finger moistened, to the 

 part, it cracks through its whole length, in nearly a strait 

 line ; they are then securely stowed away for flattening. 



Flattening. — There are two objects to be accomplished 

 by this process ; first, to convert the cylinders into planes, 

 and afterward, to anneal, or temper the glass. The struc- 

 ture intended for this purpose, is divided into three distinct 

 parts. A, the rear or entrance into the flattening oven. B,the 



