Thus a simple battery may be used either as a sender or receiver of current. Two batteries adjusted to the same center line become connected in series just as if they were connected by ultron wires.
In actual practice, however, two types of batteries are used; both the foco batteries and broadcast batteries.
Foco batteries are twin batteries, arranged to shoot a positive and a negative beam in the same direction. When these beams are made intermittent at light frequencies (though they are not light waves, nor of the same order as light waves) and are brought together, or focused, at a given spot, the space in which they cross radiates alternating ultronic current in every direction. This radiated ultralight acts like true light so long as the crossing beams vibrate at light frequencies, except in three respects: first, it is not visible to the eye; second, its “color” is exclusively dependent on the frequency of the foco beams, which determine the frequency of the alternating radiation. Material surfaces, it would appear, reflect them all in equal value, and the color of the resultant picture depends on the color of the foco frequencies. By altering these, a reddish, yellowish or bluish picture may be seen. In actual practice an orthochromatic mixture of frequencies is used to give a black, gray and white picture. The third difference is this: rays pulsating in line toward any ultron object connected with the rear plates of the twin batteries through rectifiers cannot be reflected by material objects, for it appears they are subject to a kind of “pull” which draws them straight through material objects, which in a sense are “magnetized” and while in this state offer no resistance.
Ultron, when so connected with battery terminals, glows with true light under the impact of ultralight, and if in the form of a lens or set of lenses, may be made to deliver a picture in any telescopic degree desired.
The essential parts of an ultroscope, then, are twin batteries with focal control and frequency control; an ultron shield, battery connected and adjustable, to intercept the direct rays from the “glow-spot,” with an ordinary light-shield between it and the lens; and the lens itself, battery connected and with more or less telescopic elaboration.
To look through a substance at an object, one has only to focus the glow-spot beyond the substance but on the near side of the object and slightly above it.
A complete apparatus may be “set” for “penetrative,” “distance” and “normal vision.”
In the first, which one would use to look through the forest screen from the air, or in examining the interior of a Han ship or any opaque structure, the glow-spot is brought low, at only a tiny angle above the vision line, and the shield, of course, must be very carefully adjusted.
Distance setting would be used, for instance, in surveying a valley beyond a hill or mountain; the glow-spot is thrown high to illuminate the entire scene.
In the “normal” setting the foco rays are brought together close overhead, and illuminate the scene just as a lamp of super brilliancy would in the same position.
For phonic communication a spherical sending battery is a ball of metultron, surrounded by an insulating shell of inertron, and this in turn by a spherical shell of katultron, from which the current radiates in every direction, tuning being accomplished by frequency of intermissions, with audio-frequency modulation. The receiving battery has a core pole of katultron and an outer shell of metultron. The receiving battery, of course, picks up all frequencies, the undesired ones being tuned out in detection.
Tuning, however, is only a convenience for privacy and elimination of interference in ultrophonic communication. It is not involved as a necessity, for untuned currents may be broadcast at voice-controlled frequencies, directly and without any carrier wave.
To use plate batteries or single center-line batteries for phonic communication would require absolutely accurate directional aligning of sender and receiver, a very great practical difficulty, except when sender and receiver are relatively close and mutually visible.
This, however, is the regular system used in the Inter-Gang network for official communication. The senders and receivers used in this system are set only with the greatest difficulty, and by the aid of the finest laboratory apparatus, but once set, they are permanently locked in position at the stations, and barring earthquakes or insecure foundations, need no subsequent adjustment. Accuracy of alignment permits beam paths no thicker than the old lead pencils I used to use in the Twentieth Century.
The noninterference of such communication lines, and the difficulty of cutting in on them from any point except immediately adjacent to the sender or receiver, is strikingly apparent when it is realized that every square inch of an imaginary plane bisecting the unlocated beam would have to be explored with a receiving battery in order to locate the beam itself.
A practical compromise between the spherical or universal broadcast senders and receivers on the one hand, and the single line batteries
