f the period of labor, another small airboat occupied by one man drew
up beside them and followed them to the ground. The stranger, another
white-bearded ancient, greeted Rovol cordially and was introduced to
Seaton as "Caslor, the First of Mechanism."

"Truly, this is a high point in the course of Norlaminian science, my
young friend," Caslor acknowledged the introduction smilingly. "You have
enabled us to put into practice many things which our ancestors studied
in theory for many a wearisome cycle of time." Turning to Rovol, he went
on: "I understand that you require a particularly precise directional
mechanism? I know well that it must indeed be one of exceeding precision
and delicacy, for the controls you yourself have built are able to hold
upon any point, however moving, within the limits of our immediate solar
system."

"We require controls a million times as delicate as any I have
constructed," said Rovol, "therefore I have called your surpassing skill
into co-operation. It is senseless for me to attempt a task in which I
would be doomed to failure. We intend to send out a fifth-order
projection, something none of our ancestors ever even dreamed of, which,
with its inconceivable velocity of propagation, will enable us to
explore any region in the galaxy as quickly as we now visit our closest
sister planet. Knowing the dimensions of this, our galaxy, you can
readily understand the exact degree of precision required to hold upon a
point at its outermost edge."

"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
there