As early as the 19th century, Jules Verne imagined sending a man to the moon. He described the craft as a giant artillery shell launched from the world's largest cannon. By the early 20th century, rockets proved a more reliable source of power. New refrigeration techniques allowed for liquid oxygen and hydrogen fuels while new chemical processes created a series of solid explosive propellants. The V-2, the German "Vengeance Weapon," used liquid oxygen and alcohol to give the V-2 a range of 220 miles and a velocity of 3,500 mph. Though insufficient for orbital flight, these rockets provided a glimpse of what was to come.