"Now then," he resumed, "out with the light." The next instant the place was in total darkness, the painted glass windows effectually shutting out the brilliant moonlight. There was a slight _click_. Peter, looking in the direction where he imagined the apparatus was, could discern nothing, but on the opposite wall was a small circular patch of greenish-hued light. "Seen anything like that before?" inquired his Uncle. "Rather," replied Peter. "Anti-aircraft searchlights during the war. Couldn't see the beam in its passage through air; when it hit a solid substance it lit it up." "This is somewhat similar, but very different," said Uncle Brian. "Sounds a rummy thing to say, but there you are. I'll demonstrate. On with the light, Peter." Again the room was flooded with electric light. Uncle Brian pointed to a four-cylindered motor standing in one corner. "Get to work on that," he continued. "Turn the engine over as fast as you can and see that the plugs are firing. They are already loose in the cylinders. You may as well remove the magneto dust-cap while you are about it." Peter did as requested, placing the plugs on the tops of the cylinders, so that he could observe the sparks jumping the gaps between the points and the central rods. There was no mistaking the efficient state of that magneto. It was giving a miniature Brocks' firework display. "Now!" exclaimed Uncle Brian. His nephew continued to turn the geared starting-handle for another dozen revolutions. Then he stood up and wiped the perspiration from his face. "By Jove!" he almost shouted. "It's it--absolutely _it_!" CHAPTER IX The Proving of the Rays "I hope so," rejoined Uncle Brian. "Of course, the distance is a mere nothing, but there is no reason why the gadget shouldn't work up to say 20,000 yards." "It's scuppered that magneto, any old way," declared Peter. "However did you manage it by a ray of light?" "I didn't," his uncle hastened to explain. "It's not light; it's electro-magnetism. I argued upon these lines. It's possible to send a wireless message through thousands of miles. Cannot a charge of electricity of infinitely greater strength be released through a relatively shorter distance and at the same time be confined to a definite path instead of radiating? For example: suppose Nauen wishes to communicate with, say, Moscow. Provided the receiving instrument is properly attuned, Barcelona, Clifden, and possibly New York can pick up the message. It's similar to throwing a stone in the middle of a circular pool. The ripples will eventually reach the side practically simultaneously at every point. Now, my idea was to concentrate high potential electric current and confine it to a straight and narrow path with the object of polarizing any magneto in its way." "And you've done it," declared Peter. "An aircraft wouldn't stand an earthly--I mean an aerial chance. It's bound to come down."