The Rocket and a modern English locomotive. The Rocket, the best of Robert Stephenson and Company's early locomotives, was a four-wheel engine supported on springs, with a boiler six feet long. It weighed four and a quarter tons, and in the first run on the Liverpool and Manchester railway it made an average speed of fifteen miles an hour. The "modern" English locomotive (circa 1920) weighs nearly sixty tons, and travels several times as fast as the little steam-powered Rocket of 1829. Click here to enlarge.