578 THE POPULAR SCIENCE MONTHLY. 



periods, that preceding and that following the introduction of 

 natural gas as fuel. The century opened with the almost univer- 

 sal use of wood, the new and experimental plant at Pittsburg 

 alone making use of coal. It ends with an almost universal use 

 of natural gas, where it can be obtained, and an unmistakable 

 tendency to substitute manufactured gas for coal where Nature 

 has not supplied the gaseous fuel. 



The States which now lead the glass industry, Pennsylvania 

 and New Jersey, were already at the front in the beginning of the 

 century. In Pennsylvania there were a number of enterprises on 

 foot. Philadelphia took quite an active part in this development. 

 The Kensington works, established by Robert Towars and Joseph 

 Leacock in the fall of 1771, had passed through a number of 

 hands, but was fairly continuous in its operations. It ultimately 

 came into the possession of the Rowland family, and was sold by 

 them in 1833 to Dr. Thomas W. Dyott, a notable figure in the 

 annals of our early glass-making. They were at this time the 

 most extensive glass works in the country, melting about 8,000 

 pounds of batch every day and turning out something like 1,200 

 tons of glass a year. This was chiefly in the form of bottles and 

 druggists' supplies. There were five furnaces adapted for burning 

 both coal and wood, as well as North Carolina rosin. From two 

 hundred and fifty to three hundred hands were employed in carry- 

 ing out the various operations. Dr. Dyott failed in 1838, and the 

 works were idle for several years, thus losing their former pres- 

 tige. There were also window-glass works at the Falls of the 

 Schuylkill, and another lower down on the river at South Street 

 wharf. When the first census of manufactures was taken, in 

 1810, there were two glass works in the county and one within 

 the city limits, the joint product of which amounted to only $26,- 

 000. Glass-making does not seem at that time to have been very 

 successful in Philadelphia, for in 1820 there was but one plant 

 reported in the whole county. In that year a co-operative flint- 

 glass works was started in Kensington, but it did not succeed. In 

 1840 there was but one works reported. 



Here as elsewhere throughout eastern Pennsylvania there has 

 been, since then, a steady increase in productive power, but rela- 

 tively there has been a marked decrease in the industry. The char- 

 acter of the product, too, has changed. Philadelphia probably 

 produces at the present time about two million dollars' worth of 

 glass a year. None of this, we believe, is sheet or window glass, 

 except a little for decorative windows. The most of it consists of 

 the fancier sorts of hollow ware, lamps, globes, chimneys, cut glass, 

 and other forms of domestic glassware and of articles of luxury. 

 The reason of this change is quite obvious. In the production of 

 glass in the mass, such as window glass and plate glass, Philadel- 



