I am a locomotive engine. I run upon rails, and I can draw after me a long train of c

I am a locomotive engine. I run upon rails, and I can draw after me a long train of carriages. I can also draw up steep gradients, and I can go fast or slow, as required. I can go alone, or I can haul a lot of carriages after me; and let me tell you, that I am a very powerful fellow. I can pull a train after me for sixty miles in an hour, and I can pull up a train in half