It is of course this radiation-- diffusing the effect of light, heat, or gravity over the surface of a sphere, which surface is proportionate to the square of the radius--that causes these forces to operate with an energy inversely proportionate, not to the distance, but to its square.

We had no reason to think that apergy, exempt as it is from this law, would be at all diminished by distance; and this view the rate of acceleration as I rose from the Earth had confirmed, and my entire experience has satisfied me that it is correct.

None of our experiments, however, had indicated, or could well indicate, at what rate this force can travel through space; nor had I yet obtained any light upon this point.

From the very first the current had been continuous, the only interruption taking place when I was not five hundred miles from the Earth's surface.

Over so small a distance as that, the force would move so instantaneously that no trace of the interruption would be perceptible in the motion of the Astronaut.