Stephenson, British family of inventors and railroad engineers. George (1781–1848) first worked on stationary steam engines. His first locomotive, the Blucher, took to the rails in 1814; it traveled at 4 mph (6.5 kmph). In 1825 his Locomotion carried 450 people at a rate of 15 mph (25 kmph), and the modern railroad was born. In 1829 the Rocket ran the 40 mi (65 km) of his new Manchester-Liverpool line at speeds up to 30 mph (48 kmph). His only son, Robert (1803–59), is best known as a bridge builder, notably for the tubular bridges over the Menai Straits, North Wales (1850), and the St. Lawrence River at Montreal, Canada (1859).