Jules Verne wrote his book "From Earth to the Moon" in 1865. In this novel, the Baltimore Gun Club digs a hole 270 meters deep and 18 meters in diameter in Stone's Hill, Tampa Florida. They line it with an iron tube, two meters thick and load 45,000 metric tons of dynamite in this hole. They place an iron capsule that can hold three men in this hole.
In 1901, H G Wells wrote a similar book, about shooting people to the moon with a huge cannon. However, in 1903 Konstantin Tsiolkovsky writes the first scientific appraisal of space travel by humans. Tsiolkovsky rejects the idea of using a cannon by pointing out no human could survive the blast and rapid acceleration of such a cannon. He proposed using a multiple stage rocket, that could lift a capsule at a more constant rate of acceleration. A rocket can continue to accelerate and drop off stages as it used up the fuel it was carrying. With a cannon, all the acceleration has to take place at the very start. Tsiolkovsky is thought to have been the first person to envision a practical way for humans to travel in space.
Source: "Flight: Celebrating 100 years of heavier than air Aviation" compiled by the staff of the Air and Space Museum of the Smithsonian Institution. 2003