222 WATER, HEAT, AIR, AND LIGHT IN THE HOUSE 



and 4 feet in diameter, and 

 forms a clear, transparent 

 liquid. When this is cooled, 

 it forms, before it hardens, a 

 pasty mass. While the glass 

 is pasty, vessels and other 

 objects can be made from it, 

 and it can be "blown" into 

 many shapes. 



Fig 2Q6 Window glass is made by work- 



Blowing window Glass. men who blow the pasty glass (Fig. 



206) into the form of a cylinder, 



and then cut the cylinder open lengthwise, so that it forms a sheet. 

 In a new process, glass is also drawn out by a machine into sheets 



Fig. 207. 



Casting Plate Glass at the Saint Gobain Manufactory, France. 

 Scientific American Supplement. 



From the 



