"That's one!" cried Jim. "I'm afraid we won't have time to hunt up the other right now. This bug told me that the other Mercurians are due here to-day, and I think we had better form ourselves into a reception committee and go up to the hole to meet them."

He sent the ship at high speed over the city until we hovered over the laboratory. We stopped for a moment, and Jim stepped to the radio telephone.

"h.e.l.lo, Williams," he said, "how are things going? That's fine. In an hour, you say? Well, speed it up as much as you can; we may call for it soon."

He turned both stern motors to full power, and we shot up like a rocket toward the hole in the protective layer through which the invaders had entered. In ten minutes we were at the alt.i.tude of the guard ships and Jim asked if anything had been seen. The report was negative; Jim left them below the layer and sent our flyer up through the hole into s.p.a.ce.

We reached the outer surface in another ten minutes and we were none too soon. Hardly had we debouched from the hole than ahead of us we saw another Mercurian flyer. It was a lone one, and Jim bent over the captive and held a hastily made sketch before him. The sketch showed three Mercurian flyers, one on the ground, one wrecked and the third one in the air. He touched the drawing of the one in the air and pointed toward our port hole and looked questioningly at the beetle. The insect inspected the flyer in s.p.a.ce and nodded.

"Good!" cried Jim. "That's the third of the trio who came ahead as scouts. Get your gun ready, First Mortgage: we're going to pick him off."

Our ship approached the doomed Mercurian. Again I waited until we were within four hundred yards; then I pressed the b.u.t.ton which hurled it, a crumpled wreck, onto the outer surface of the heaviside layer.

"Two!" cried Jim as we backed away.

"Here come plenty more," I cried as I swung the searchlight. Jim left his controls, glanced at the screen and whistled softly. Dropping toward us from s.p.a.ce were hundreds of the Mercurian ships.

"We got here just in time," he said. "Break out your extra ammunition while I take to the hole. We can't hope to do that bunch alone, so we'll fight a rearguard action."

Since our bow gun would be the only one in action, I hastily moved the spare boxes of ammunition nearer to it while Jim maneuvered the Hadley over the hole. As the Mercurian fleet came nearer he started a slow retreat toward the earth. The Mercurians overtook us rapidly; Jim locked his controls at slow speed down and hurried to the bow gun.

"Start shooting as soon as you can," he said. "I'll keep the magazine filled."

I swung the gun until the cross-hairs of the screen rested full on the leading ship and pressed the b.u.t.ton. My aim was true, and the shattered fragments of the ship fell toward me. The balance of the fleet slowed down for an instant; I covered another one and pressed my b.u.t.ton. The ship at which I had aimed was in motion and I missed it, but I had the satisfaction of seeing another one fall in fragments. Jim was loading the magazine as fast as I fired. I covered another ship and fired again.

A third one of our enemies fell in ruins. The rest paused and drew off.

"They're retreating, Jim!" I cried.

"Cease firing until they come on again," he replied is he took the sh.e.l.ls from the magazines of the other guns and piled them near the bow gun.

I held my fire for a few minutes. The Mercurians retreated a short distance and then came on again with a rush. Twenty times my gun went off as fast as I could align it and press the trigger, and eighteen of the enemy ships were in ruins. Again the Mercurians retreated. I held my fire. We were falling more rapidly now and far below we could see the black spots which were the guard ships. I told Jim that they were in sight; he stepped to the radio telephone and ordered them to keep well away from the hole.

Again the Mercurian ships came on with a rush, this time with beams of orange light stabbing a way before them. When I told Jim of this he jumped to the controls and shot our ship down at breakneck speed.

"I don't know what sort of fighting apparatus they have, but I don't care to face it," he said to me. "Fire if they get close; but I hope to get out of the hole before they are in range."

Fast as we fell, the Mercurians were coming faster, and they were not over eight hundred yards from us when he reached the level of the guard ships. Jim checked our speed; I managed to pick off three more of the invaders before we moved away from the hole. Jim stopped the side motion and jumped to the radio telephone.

"h.e.l.lo, Williams!" he shouted into the instrument. "Are you ready down there? Thank G.o.d! Full power at once, please!

"Watch what happens," he said to me, as he turned from the instrument.

Some fifty of the Mercurian flyers had reached our level and had started to move toward us before anything happened. Then from below came a beam of intolerable light. Upward it struck, and the Mercurian ships on which it impinged disappeared in a flash of light.

"A disintegrating ray," explained Jim. "I suspected that it might be needed and I started Williams to rigging it up early this morning. I hated to use it because it may easily undo the work that six years have done in healing the break in the layer, but it was necessary. That ends the invasion, except for those ten or twelve ships ahead of us. How is your marksmanship? Can you pick off ten in ten shots?"

"Watch me," I said grimly as the ship started to move.

Pride goeth ever before a fall: it took me sixteen shots to demolish the eleven ships which had escaped destruction from the ray. As the last one fell in ruins, Jim ordered the ray shut off. We fell toward the ground.

"What are we going to do with our prisoner?" I asked.

Jim looked at the beetle meditatively.

"He would make a fine museum piece if he were stuffed," he said, "but on the whole, I think we'll let him go. He is an intelligent creature and will probably be happier on Mercury than anywhere else. What do you say that we put him on his ship and turn him loose?"

"To lead another invasion?" I asked.

"I think not. He has seen what has happened to this one and is more likely to warn them to keep away. In any event, if we equip the guard ships with a ray that will show the Mercurian ships up and keep the disintegrating ray ready for action, we needn't fear another invasion.

Let's let him go."

"It suits me all right, Jim, but I hold out for one thing. I will never dare to face McQuarrie again if I fail to get a picture of him. I insist on taking his photograph before we turn him loose."

"All right, go ahead," laughed Jim. "He ought to be able to stand that, if you'll spare him an interview."

An hour later we watched the Mercurian flyer disappear into s.p.a.ce.

"I hope I've seen the last of those bugs," I said as the flyer faded from view.

"I don't know," said Jim thoughtfully. "If I have interpreted correctly the drawings that creature made, there is a race of manlike bipeds on Mercury who are slaves to those beetles and who live and die in the horrible atmosphere of a radium mine. Some of these days I may lead an expedition to our sister planet and look into that matter."

MECHANICAL VOICES FOR PHONE NUMBERS

New developments whereby science goes still farther in its a.s.sumption of human attributes were described and demonstrated recently by Sergius P. Grace, a.s.sistant Vice-President of Bell Telephone Laboratories, where the developments were conceived and worked out.

One development described, and soon to be put into service in New York, transforms a telephone number dialed by a subscriber into speech. Although the subscriber says not a word the number dialed is spoken aloud to the operator.

The device is expected to simplify and speed the hooking together of automatic and voice-hand-operated telephone exchanges, and also to speed long-distance calls from automatic phones through rural exchanges.

The numbers which can thus be spoken are recorded on talkie films and those which are to go into use here have already been made, all by an Irish girl said to have the best voice among the city's "number, please" girls.

Mr. Grace demonstrated this device by carrying into the audience a telephone with a long cord connected with a loud speaker on the stand, which represented central. A member of the audience was requested to dial a number, and choose 5551-T, the letter T representing the exchange.

This number the spectator dialed on the phone Mr. Grace carried.

There was no sound but the clicking of the dial. Then, two seconds later, the loudspeaker spoke up clearly, in an almost human voice, "5551 T."

As for the recording of the sound films, there is a film for each of the ten Arabic numerals from zero to nine, and these wound on revolving drums. The dial on the telephone automatically sets in action the drum corresponding to the numeral moved on the dial.