As a purely manufacturing business the general cement industry is one of even remote antiquity, and if Edison had entered into it merely as a commercial enterprise by following paths already so well trodden, the fact would hardly have been worthy of even passing notice. It is not in his nature, however, to follow a beaten track except in regard to the recognition of basic principles; so that while the manufacture of Edison Portland cement embraces the main essentials and familiar processes of cement- making, such as crushing, drying, mixing, roasting, and grinding, his versatility and originality, as exemplified in the conception and introduction of some bold and revolutionary methods and devices, have resulted in raising his plant from the position of an outsider to the rank of the fifth largest producer in the United States, in the short space of five years after starting to manufacture.

Long before his advent in cement production, Edison had held very pronounced views on the value of that material as the one which would obtain largely for future building purposes on account of its stability. More than twenty-five years ago one of the writers of this narrative heard him remark during a discussion on ancient buildings: "Wood will rot, stone will chip and crumble, bricks disintegrate, but a cement and iron structure is apparently indestructible. Look at some of the old Roman baths. They are as solid as when they were built." With such convictions, and the vast fund of practical knowledge and experience he had gained at Edison in the crushing and manipulation of large masses of magnetic iron ore during the preceding nine years, it is not surprising that on that homeward railway journey, mentioned at the close of the preceding chapter, he should have decided to go into the manufacture of cement, especially in view of the enormous growth of its use for structural purposes during recent times.