A sound you may never have heard before, is one of the most mournful, lonesome and yet friendly sounds in the whole world. It's a locomotive whistle, the old fashioned kind, which was part of a coal burning steam engine. There are a few in active service here and there, but for the most part, they have been replaced by modern, electric or diesel engines. But the locomotive had more to do with the expansion of our country than any other one thing...