Talbot interrupted. "Pardon me, General, but the enemy would have no difficulty in spotting such a maneuver. What chance would your soldiers have against a shower of jungle seed? You would only be sending them to destruction. No, the only way is for someone familiar with those old underground diggings to enter them, locate the birds and the machines and blow them up." "But who----" "Myself. Listen. This is the plan. About five years ago my company mined for copper and other ores about a half mile above the Wiley claim. I was in charge of operations. That is how I know the ground so well. One of our northern leads broke through into a tunnel of the abandoned mine. When copper prices were shot to hell in the depression of 1930 we quit taking out ore; but when I went through the place eighteen months ago it was still possible to crawl from one mine to another. Of course earth and rock may have fallen since then, but I don't believe the way is yet blocked. If I were dropped in that vicinity at night with another man and the necessary tools and explosives...." The general thought swiftly. "An auto-gyroscope could land you all right. There's one here now. But what about the second man to accompany you?" Manuel said quickly, "I'm going with the boss." "You, Manuel," Talbot said roughly. "Don't be a fool. If anything should happen to me--well, I've lived my life; but you're only a kid." Manuel's face set stubbornly. "An experienced mining man you need, is it not? In case there should be difficulties. And I am experienced. Besides, senores," he said simply, "my wife and child are somewhere in those mountains ... above Oracle...." Talbot gripped his hand in quick sympathy. "All right, Manuel; come if you like." A moonless sky hung above them as they swung over the dark and jungle-engulfed deserted city of Tucson, a sky blazing with the clarity of desert stars, and to the south and west shot through with the beams of great searchlights. Flying at a lofty altitude to avoid contact with drifting globes or betrayal of their coming with no lights showing aboard their craft save those carefully screened and focused on the instrument board, it was hard to realize that the fate of America, perhaps of the world, hung on the efforts of two puny individuals. Everything seemed unreal, ghost-like, and suddenly the strangeness of it all came over Talbot and he felt afraid. The noiseless engine made scarcely a sound; the distant rumble of gunfire sounded like low and muttering thunder. They had come by way of Tucson so as to pick up a ten-gallon tube of concentrated explosive gas at the military camp in the Tucson mountains. "This gas," the general had assured them, "has been secretly developed by the chemical branch of the War Department and is more powerful than TNT or nitro-glycerin. It is odorless, harmless to breathe and exploded by a wireless-radio device."