Jules Verne,
From the Earth to the Moon — Chapter IV
“ Regarding the first question, "Is it possible to transmit a projectile up to the moon?"Answer.-- Yes; provided it possess an initial velocity of 1,200 yards per second; calculations prove that to be sufficient. In proportion as we recede from the earth the action of gravitation diminishes in the inverse ratio of the square of the distance; that is to say, at three times a given distance the action is nine times less. Consequently, the weight of a shot will decrease, and will become reduced to zero at the instant that the attraction of the moon exactly counterpoises that of the earth ”
