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 button. 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 button. 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 shells 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.
“Hello, Williams!” he shouted into the instrument. “Are you ready down there? Thank God! 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 space.
“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.”