as a test; and the temperature rose only a single degree Fahrenheit () during a trip lasting 101 hours. Caspar Pfaudler invented a method of lining cast iron tanks with glass while working with the brewing industry. The first glass-lined tanks were built by the Dickson Manufacturing Company in 1887; and the Pure Food and Drug Act of 1906 increased use of these tanks for milk products. The Boston and Maine Railroad (B&M) was using a milk car with glass-lined steel tanks in 1910. Pfaudler designed what became a standard milk car with two tanks inside a closed car. Earlier cars featured a removable roof to replace damaged tanks, but the tanks proved durable enough to eliminate that feature from later production. Pfaudler cars included brine coils to cool the car at the creamery, and an electric stirring mechanism to keep butterfat distributed through the milk and minimize deposition on the interior of the tank. Stirring also helped maintain a uniform temperature throughout the tank. Peak use and decline Large cities in the eastern United States encouraged nearby rural areas to specialize in production of milk, but milk cars were transporting milk up to by 1900. Railroads connecting these rural areas to cities scheduled daily milk trains (sometimes called milk runs) to pick up loaded milk cars from collection points along their route. These trains sometimes carried a mail car and a passenger car. Milk trains usually arrived at their destination cities in the late evening so the milk could be unloaded and processed for delivery the following morning. A returning train of empty milk cars departed the city in the early morning hours. These were often the last scheduled passenger trains serving those rural areas, and most milk was traveling in highway trucks by 1960. Rail transport of milk peaked in 1931 when the Official Railway Equipment Register listed 2174 railway-owned milk cars and 480 cars owned by shippers. Most railway-owned milk cars were made of wood; but the Erie Railroad built over two hundred steel cars in the 1930s, and fifty steel cars delivered to B&M in 1958 were the last milk cars built for United States railroads. The last fifteen were numbered 1900-1914, and equipped with gasoline-powered mechanical refrigeration to transport bottled milk as a unit train from Bellows Falls, Vermont to First National Stores in Somerville, Massachusetts. B&M cars numbered 1915-1934 were built without mechanical refrigeration