386 THE AMERICAN JOURNAL OF SOCIOLOGY
but partly, also, I am convinced, because the fact has been ignored that no system is a stable one, but that, on the contrary, stem is steadily undergoing modifications so far reach- ing as to be of greater moment than the present conditions. These changes are complex and often elusive. Many must escape the notice of the student. But certain ones may be pointed out. The facts regarding the gas companies of Massa- chusetts have been gathered now for ten years, and evidence of certain changes may be derived from a collation of the facts contained in the eleven annual reports of the board of gas and electric light commissioners of that state.
The manufacture of coal gas has increased with great rapidity from 2,624,570,655 cubic feet in the year ending June 30, 1886, to 4,810,048,617 cubic feet in the year ending June 30, 1895, an increase of over two and one-sixth billion cubic feet or 83.3 per cent, in nine years.
While the output of coal gas has thus nearly doubled, the manufacture of water gas has sprung up from almost nothing. In the year ending June 30, 1887, only 28,354,300 cubic feet of water gas were made, but eight years later the reported output was over eighty-five times as great, 2,413,265,558 cubic feet, almost exactly one-half the amount of coal gas produced the same year. The system of electric lighting has also developed from almost nothing during the same period. Yet notwithstand- ing these powerful rivals and competitors, the output of coal gas increased about five-sixths in nine years.
Still the gas unaccounted for and presumably lost through leakage has remained nearly stationary, increasing in eight years (1887-95) l ess tnan 6 percent. (5.9 per cent.), or perhaps one-twelfth as fast as the total product. The proportion of unaccounted-for coal gas to the total output was about one- twelfth (8.44 per cent.) in 1886-7, and but little over one- twentieth (5.14 per cent.) in 1894-5. The following table gives the figures for all the companies which produced over fifty million cubic feet of gas in 1894-5 and for which the facts are published :
