periods, that preceding and that following the introduction of natural gas as fuel. The century opened with the almost universal 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 carrying out the various operations. Dr. Dyott failed in 1838, and the works were idle for several years, thus losing their former prestige. 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 relatively there has been a marked decrease in the industry. The character 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-
