"It might be likened to the light-pressure effects of a spotlight and a star. The spotlight would push the sun with a force that was constant; no matter what the distance, while the light pressure of the sun would vary as the inverse square of the distance.
"But remember, it is not a body that pulls another body, but a gravitational field that pulls another. The field is in space. A normal field is necessarily attached to the matter that it represents, or that represents it as you prefer, but this artificial field has no connection in the form of matter. It is a product of a machine, and exists only as a strain in space. To move it you must move all space, since it, like artificial matter, exists only where it is created in space.
"Do you see now why the law of action and reaction is apparently flouted? Actually the reaction is taken up by space."
Arcot rose, and stretched. Morey and Wade had been looking at him, and now they asked when he intended leaving for the intergalactic spaces.
"Now, I think. We have a lot of work to do. At present we have the mathematics of the artificial matter to carry on, and the math of the artificial gravity to develop. We gave the Sirians all we had on artificial matter and on moleculars.
"They gave us all they had—which wasn't much beyond the artificial gravity, and a lot of work. At any rate, let's go!"
Chapter XIII
ATTACKED
The Ancient Mariner stirred, and rose lightly from its place beside the city. Visible over the horizon now, and coming at terrific speed, was a fleet of seven Thessian ships.