First proposal of using rockets for space flight

In 1861, Scottish astronomer and mathematician William Leitch published one of the earliest scientific proposals advocating the use of rockets for space travel. His essay, titled A Journey Through Space, appeared in an Edinburgh journal and was later included in his 1862 book God’s Glory in the Heavens. At a time when space travel was largely confined to speculative fiction, Leitch’s work stood out for its grounding in established physical principles. Leitch applied Newton’s third law of motion to explain how rockets generate thrust through internal reaction, correctly identifying that propulsion does not require an external medium such as air. He also noted that rockets would operate more effectively in the vacuum of space, where there is no atmospheric resistance. This understanding anticipated key principles that would later underpin modern rocketry. His analysis contrasted with other contemporary ideas about reaching space, particularly the concept of launching projectiles using large cannons, which he recognized as impractical for carrying humans due to the extreme forces involved. Published several decades before the work of pioneers such as Konstantin Tsiolkovsky and Robert Goddard, Leitch’s proposal represents an early theoretical step toward spaceflight based on scientific reasoning. It also predates Jules Verne’s 1865 novel From the Earth to the Moon, which popularized a different, less feasible method of space travel using a giant cannon. Leitch’s work remained relatively obscure but is recognized in historical accounts as an early contribution to the scientific understanding of rocket propulsion.