"This is an ultra-short wave detector," he explained to Carnes. "It will receive vibrations to the lowest limit of waves that we have ever been able to measure. The X-ray is high on the scale and even the cosmic ray is far above its lower limit of detection. We are hunting for an electro-magnet, the largest and strangest electro-magnet that has ever been constructed. Perhaps it would be more accurate to say that we are seeking for a generator of magnetic force. It does not generate the ordinary magnetism which attracts iron and steel, nor the special type of magnetism which we call gravity, but something between the two. It attracts the sun enough to disturb the tilt of the earth's axis, but not enough to pull the earth out of its orbit. Such a device should give out a wave that can be detected, if we get a receiver delicate enough and operating on the right wave length."
He spent hours improving and refining the apparatus, but in the end he confessed himself beaten.
"It's no use, Carnes," he said the day after Cape Kanin faded from view to the north. "Either the apparatus we are seeking gives out no wave that we can detect or my apparatus is faulty. Luckily we have other things to guide us."
"What are they, Doctor?"
"The facts that Saranoff must have easy transportation and a source of power. The first precludes him from locating his station far from the sea-coast and the second indicates that it will be near a river or other source of power. The only Russian points on the sixty-fifth parallel that are open to water transport are the Gulf of Anadyr, north of Kamchatka, and the vicinity of Archangel. I passed up Kamchatka because it would mean too long a haul through unfriendly waters from Leningrad and because there is not much water power. Archangel is easy of access at this time of the year and it has the Dwina river for power. That will be our first line of search."
"We will explore by plane, of course?"
"Certainly. We wouldn't get far on foot, especially as neither of us speaks Russian. We'll head south for another day and then— What's that?"
He paused and listened. From the distance came a dull drone of sound which brought him to his feet with a start. He raced out onto deck with Carnes at his heels. Far overhead in the blue, a tiny speck of black hovered.
"We're on the right trail, Carnes," he said grimly. The plane passed over them. In huge circles it sank toward the ground. Dr. Bird turned to Captain Evans. Orders flew from the bridge and a detail of marines rapidly stripped the covers from the two forward anti-aircraft rifles.
"I dislike to fire on that craft before it makes a hostile demonstration, Dr. Bird," demurred Captain Evans. "We are at peace with Russia. My action in firing might precipitate a war, or in any event, serious diplomatic misunderstandings."