But the great Pittsburg attraction is the multitude of factories that are its pride and create its prosperity. Some of these are among the greatest in the world--the Edgar Thomson Works and Homestead Works of the Carnegie Steel Company, the Duquesne Steel Works, the Keystone Bridge Company, and others. The Edgar Thomas mills make over a million tons of rails a year, and at Homestead fifteen hundred thousand tons of steel will be annually produced, this being the place where nickel-steel armor-plates for the navy are manufactured. They largely use natural gas, and employ at times ten thousand men at the two great establishments. The Duquesne Works, just above Homestead on the Monongahela, have the four largest blast furnaces in the world, producing twenty-two hundred tons of pig-iron daily. The Keystone Bridge Works cover seven acres, and have made some of the greatest steel bridges in existence. The Westinghouse Electrical Works manufacture the greatest dynamos, including those of the Niagara Power Company, and the Westinghouse Air-Brake Works is also another extensive establishment. In the Pittsburg district, covering about two hundred square miles, the daily product of mines and factories is estimated at $6,000,000. The two men whose names are most closely connected with Pittsburg's vast industrial development are Andrew Carnegie and George Westinghouse. Carnegie was born at Dunfermline, Scotland, in 1837, and his father, a potter, brought him to Pittsburg when eleven years old. He began life as a telegraph messenger boy, attracted the attention of Colonel Thomas A. Scott, and was by him brought into the service of the Pennsylvania Railroad. Then he entered business, and became the greatest developer of the iron and steel industries of Pittsburg and its wealthiest resident. He some time ago sold out his interests to the Carnegie Steel Company, in which he is largely interested. Westinghouse, born in New York State in 1846, combined with business tact the genius of the inventor. He invented and developed the railway air-brake now in universal use, has established a complete electrical lighting and power system, and was the chief adapter of natural gas to manufacturing and domestic uses, being the inventor of many ingenious contrivances for its introduction and economical employment. He had a gas well almost at his door, for Pittsburg overlaid a great deposit. The enormous coal measures underlying and surrounding the city have been its most stable basis for industry and profit, as the Pittsburg coal-field is one of enormous output. The deposits of Lake Superior furnish the ores for its furnaces, and the railroad development is such that each enormous establishment now has its special railroad to fetch in the ores from Lake Erie, where they are brought by vessels. Across in Allegheny City, where most of these ore-bringing roads go out, about one hundred acres in the centre of the city are reserved