This is pure fun from start to finish, and doesn’t take itself too seriously at any point. A gun club in the USA, disheartened by peace breaking out and not having anyone to shoot at, decides to build an enormous cannon to fire at the moon.
Amazingly, despite this being written around 1865, the science is pretty spot on; Verne describes the harshness of space and the mechanics of travelling to the moon pretty accurately, even down to things alongside the capsule travelling on the same orbit. He even sites the cannon in Florida.
In places, it’s almost a prototype for Apollo 13; the voyage runs into similiar problems, and there are questions about whether there will be enough air to return when they get pushed off course and can only orbit the moon. Even at one point, firing the ‘engine’ that was to have landed them on the moon to return them to earth.
There are scientific errors, of course, some of them unforgivable – at two points, the characters open a window on their capsule! And there’s no mention of weightlessness, despite Verne commenting on how everything around them is travelling at the same velocity.
But overall, a fantastic romp into a Victorian idea of outer space. Loved it.