The first Portland cement ever made in the United States was turned out by David O. Saylor, of Coplay, Pa., in 1875, but the development of the new industry was very slow, as builders and engineers seemed to be blind to the great possibilities of the material that built Imperial Rome. In 1890, nearly twenty years after the process was introduced in America, only 335,500 barrels of Portland cement were manufactured in this country. The country woke up to the situation a few years later, and in 1905 there were manufactured in the United States 35,246,812 barrels of Portland cement. In 1911 the industry turned out the stupendous total of 77,877,236 barrels.
This was because the age of concrete had dawned on the world and man had learned in those years that by mixing gravel and sand with cement he could make a material cheaper, more easily handled, and far more lasting than wood, brick or some stone.
As Edison once said to some of his associates:
"I think the age of concrete has started, and I believe I can prove that the most beautiful houses that our architects can conceive can be cast in one operation in iron forms at a cost, which, by comparison with present methods, will be surprising. Then even the poorest man among us will be enabled to own a home of his own—a home that will last for centuries with no cost for insurance or repairs, and be as exchangeable for other property as a United States bond."
The technical definition of concrete is as follows: "Concrete is a species of artificial stone formed by mixing cement mortar with broken stone or gravel. Cement is the active element called the matrix and the sand and stone forms the body of the mixture called the aggregate."
The ingredients are mixed in different proportions for different work. A common proportion is 1 part cement, 2 parts sand, and 5 parts broken stone or gravel. Cement users speak of this as a "1: 2: 5 mixture." Sometimes the gravel is left out and a mixture of 1 part cement to 3 or 4 parts sand is made. The cement binds the mass together and sand fills up any little vacant spaces about the gravel, making what is called a dense mixture.
THE SILENT KNIGHT MOTOR