LIGHT 241 



sodium silicate, a harder glass results. This glass is 

 known by such names as hard glass, Bohemian glass, and 

 crown glass (Figures 215, 216). 



Artificial Lighting. A history of artificial lighting 

 includes stories of the use of many different materials. 



Copyright by Underwood & Underwood, N. Y. 

 FIG. 216. Glass Making. 

 Casting and rolling sheets of plate glass, 12^ X 21 feet, Tarantum, Pa. 



Prior to 1860 the common means of lighting were the 

 burning of wood in the fireplace pine knots gave the 

 most light because of the turpentine they contained 



