"Truly, a problem worthy of any man's brain," Caslor replied after a moment's thought. "Those small circles," pointing to the forty-foot hour and declination circles which Seaton had thought the ultimate in precise measurement of angular magnitudes, "are of course useless. I shall have to construct large and accurate circles, and in order to produce the slow and fast motions of the required nature, without creep, slip, play, or backlash, I shall require a pure torque, capable of being increased by infinitesimal increments.... Pure torque."
He thought deeply for a time, then went on: "No gear-train or chain mechanism can be built of sufficient tightness, since in any mechanism there is some freedom of motion, however slight, and for this purpose the director must have no freedom of motion whatever. We must have a pure torque—and the only possible force answering our requirements is the four hundred sixty-seventh band of the fourth order. I shall therefore be compelled to develop that band. The director must, of course, have a full equatorial mounting, with circles some two hundred and fifty feet in diameter. Must your projector tube be longer than that, for correct design?"
"That length will be ample."
"The mounting must be capable of rotation through the full circle of arc in either plane, and must be driven in precisely the motion required to neutralize the motion of our planet, which, as you know, is somewhat irregular. Additional fast and slow motions must, of course, be provided to rotate the mechanism upon each graduated circle at the will of the operator. It is my idea to make the outer supporting tube quite large, so that you will have full freedom with your inner, or projector tube proper. It seems to me that dimensions X37 B42 J867 would perhaps be as good as any."
"Perfectly satisfactory. You have the apparatus well in mind."
"These things will consume some time. How soon will you require this mechanism?" asked Caslor.
"We also have much to do. Two periods of labor, let us say: or, if you require them, three."
"It is well. Two periods will be ample time: I was afraid that you might need it today, and the work cannot be accomplished in one period of labor. The mounting will, of course, be prepared in the Area of Experiment. Farewell."
"You aren't going to build the final projector here, then?" Seaton asked as Caslor's flier disappeared.
"We shall build it here, then transport it to the Area, where its dirigible housing will be ready to receive it. All mechanisms of that type are set up there. Not only is the location convenient to all interested, but there are to be found all necessary tools, equipment and material. Also, and not least important for such long-range work as we contemplate, the entire Area of Experiment is anchored immovably to the solid crust of the planet, so that there can be not even the slightest vibration to affect the direction of our beams of force, which must, of course, be very long."