boilers in various sizes that can be combined to suit a customer's requirements. Some of the basic designs were kept in stock, and could be ordered off the shelf. 1890: Porter built their first compressed-air locomotive, for a coal mine in Pennsylvania. Air was stored in two tanks, and used to drive the pistons instead of steam. This allowed locomotive use inside mines without the fumes of burning coal, or the dangers of high-pressure steam. Porter went on to build over 400 compressed-air locomotives for use in mines, plants, and the street railways of New Orleans. Others built compressed-air locomotives, but by 1900 Porter had captured 90% of the market. 1899: Henry Porter incorporated the company as the H.K. Porter Co., Inc. He built a new plant at 49th and Harrison Street in Pittsburgh. Production peaked in 1906, with almost 400 locomotives built that year. 1911: Porter built their first gasoline-powered locomotive, and in 1915 they built their first fireless locomotive, using a large pressure vessel to hold steam and hot water in place of a boiler. These proved to be more useful than compressed-air locomotives, and soon Porter dominated this niche market. 1919: Porter was selected to build twenty 4-6-0 45-class mainline locomotives for the Manila Railroad Company in the Philippines to replace its aging British tank locomotives. The class weighed and were one of the largest locomotives built by the company. Its efficiency and low cost of maintenance led the Manila Railroad to use the Porter design for larger locomotives built by Alco and Baldwin. 1921: The H.K. Porter Co. was prosperous, enjoying a post-World War I reconstruction boom in Europe, and a road construction boom in the US. Porters were a favorite choice among grading contractors, who used light, portable tracks to carry the wooden tipper-cars that were the earthmoving equipment of the day. Henry Porter, still running the company at age 81, died on April 10. 1939: After a long decline, the H.K. Porter Co. declared bankruptcy. Thomas Mellon Evans purchased the company, determined to turn it around. He bought other manufacturing companies, adding them to his collection. Locomotive production increased again during World War II, and the company was recognized for its service to the country in 1942, but demand for steam locomotives dwindled post-war, and H.K. Porter became primarily a holding company for the many subsidiaries Evans had acquired. 1950: The company built its