In proportion to the distance from the earth the force of gravitation diminishes in an inverse ratio to the square of the distance--that is to say, that for a distance three times greater that force is nine times less.

In consequence, the weight of the projectile will decrease rapidly, and will end by being completely annulled at the moment when the attraction of the moon will be equal to that of the earth--that is to say, at the 47/52 of the distance.

At that moment the projectile will have no weight at all, and if it clears that point it will fall on to the moon only by the effect of lunar gravitation.

The theoretic possibility of the experiment is, therefore, quite demonstrated; as to its success, that depends solely in the power of the engine employed.
"Regarding question No.

2, 'What is the exact distance that separates the earth from her satellite ?' "The moon does not describe a circle round the earth, but an ellipse, of which our earth occupies one of the foci; the consequence is, therefore, that at certain times it approaches nearer to, and at others recedes farther from, the earth, or, in astronomical language, it has its apogee and its perigee.