both out of the way for a thousandth of that amount. The question is20
not to find one concern who might be backing a thing like that, but to pick out the one who is backing it."
After thinking deeply for a few moments he went on:
"The idea was taken from your demonstration in the Bureau, either by an eye-witness or by someone who heard about it afterward, probably the former. Even though it failed, one man saw the possibilities. Who was that man? Who was there?"
"Oh, a lot of the fellows were there. Scott, Smith, Penfield, DuQuesne, Roberts--quite a bunch of them. Let's see--Scott hasn't brains enough to do anything. Smith doesn't know anything about anything except amines. Penfield is a pure scientist, who wouldn't even quote an authority without asking permission. DuQuesne is ... hm-m ... DuQuesne ... he ... I...."
"Yes. DuQuesne. I have heard of him. He's the big black fellow, about your own size? He has the brains, the ability, and the inclina-tion, has he not?"
"Well, I wouldn't want to say that. I don't know him very well, and personal dislike is no ground at all for suspicion, you know." "Enough to warrant investigation. Is there anyone else who might have reasoned it out as you did, and as DuQuesne possibly
could?"
"Not that I remember. But we can count DuQuesne out, anyway, because he called me up this afternoon about some notes on gal-lium; so he is still in the Bureau. Besides, he wouldn't let anybody else investigate it if he got it. He would do it himself, and I don't think he would have blown himself up. I never did like him very well personally--he's such a cold, inhuman son of a fish--but you've got to hand it to him for ability. He's probably the best man in the world today on that kind of thing."
"No, I do not think that we will count him out yet. He may have had nothing to do with it, but we will[405] have him investigated nevertheless, and will guard against future visitors here."
Turning to the telephone, he called the private number of a well-known detective.
"Prescott? Crane speaking. Sorry to get you out of bed, but I should like to have a complete report upon Dr. Marc C. DuQuesne, of the Rare Metals Laboratory, as soon as possible. Every detail for the last two weeks, every move and every thought if possible. Please keep a good man on him until further notice.... I wish you would send two or three guards out here right away, tonight; men you can trust and who will stay awake.... Thanks. Good night."
CHAPTER V Direct Action
Seaton and Crane spent some time developing the object-compass. Crane made a number of these instruments, mounted in gymbals, so that the delicate needles were free to turn in any direction whatever. They were mounted upon jeweled bearings, but bearings
made of such great strength, that Seaton protested.
"What's the use, Mart? You don't expect a watch to be treated like a stone-crusher. That needle weighs less than half a gram. Why mount it as though it weighed twenty pounds?"
"To be safe. Remember the acceleration the Lark will be capable of, and also that on some other worlds, which we hope to visit, this needle will weigh more than it does here."
"That's right, Mart, I never thought of that. Anyway, we can't be too safe to suit me."
When the compasses were done and the power through them had been adjusted to one-thousandth of a watt, the lowest they could maintain with accuracy, they focused each instrument upon one of a set of most carefully weighed glass beads, ranging in size from a pin-head up to a large marble, and had the beads taken across the country by Shiro, in order to test the sensitiveness and accuracy of the new instruments. The first test was made at a distance of one hundred miles, the last at nearly three thousand. They found,
as they had expected, that from the weight of the object and the time it took the needle to come to rest after being displaced from its line by a gentle tap of the finger, they could easily calculate the distance from the compass to the object. This fact pleased Crane immensely, as it gave him a sure means of navigation in space. The only objection to its use in measuring earthly distances was its extreme delicacy, the needle focused upon the smallest bead in the lot at a distance of three thousand miles coming to rest in little
21
more than one second.
The question of navigation solved, the two next devoted themselves to perfecting the "Xplosive bullet," as Seaton called it. From his notes and equations Seaton calculated the weight of copper necessary to exert the explosive force of one pound of nitroglycer- in, and weighed out, on the most delicate assay-balance made, various fractions and multiples of this amount of the treated copper, while Crane fitted up the bullets of automatic-pistol cartridges to receive the charges and to explode them on impact.
They placed their blueprints and working notes in the safe, as usual, taking with them only those notes dealing with the object-compass and the Xplosive bullet, upon which they were still working. No one except Shiro knew that the original tracings, from which the blueprints had been made, and their final, classified notes were always kept in the vault. They cautioned him and the three guards to keep a close watch until they returned. Then they set out in the biplane, to try out the new weapon in a lonely place where the exploding shells could do no damage.
They found that the Xplosive came fully up to expectations. The smallest charge they had prepared, fired by Crane at a great stump
a full hundred yards away from the bare, flat-topped knoll that had afforded them a landing-place, tore it bodily from the ground and
reduced it to splinters, while the force of the explosion made the two men stagger.
"She sure is big medicine!" laughed Seaton. "Wonder what a real one will do?" and drawing his pistol, he inserted a cartridge carrying
a much heavier charge.
"Better be careful with the big ones," cautioned Crane. "What are you going to shoot at?"
"That rock over there," pointing to a huge boulder half a mile away across the small valley. "Want to bet me a dinner I can't hit it?" "No. You forget that I saw you win the pistol trophy of the District."
The pistol cracked, and when the bullet reached its destination the great stone was obliterated in a vast ball of flame. After a mo-ment there was a deafening report--a crash as though the world were falling to pieces. Both men were hurled violently backward, stumbling and falling flat. Picking themselves up, they looked across the valley at the place where the boulder had stood, to see only an immense cloud of dust, which slowly blew away, revealing a huge hole in the ground. They were silent a moment, awed by the frightful power they had loosed.
"Well, Mart," Seaton broke the silence, "I'll say those one-milligram loads are plenty big enough. If that'd been something coming after us--whether any possible other-world animal, a foreign battleship, or the mythical great sea-serpent himself, it'd be a good Indian now. Yes? No?"
"Yes. When we use the heavier charges we must use long-range rifles. Have you had enough demonstration or do you want to shoot
some more?"
"I've had enough, thanks. That last rock I bounced off of was no pillow, I'll tell the world. Besides, it looks as though I'd busted a leg or two off of our noble steed with my shot, and we may have to walk back home."
An examination of the plane, which had been moved many feet and almost overturned by the force of the explosion, revealed
