Answer:
The firing of the Columbiad.
The story opens some time after the end of the American Civil War. The Baltimore Gun Club, a society dedicated to the design of weapons of all kinds (especially cannons), comes together when Impey Barbicane, its president, calls them to support his latest idea. He's done some calculations, and believes that they could construct a cannon capable of shooting a projectile to the Moon. After receiving the support of his companions, another meeting is held to decide the place from which the projectile will be fired, the dimensions and materials of both the cannon and the projectile, and which kind of powder they are to use.
