"I think we're far enough out. We'll drop our first bomb here."
He pressed the release switch as he spoke. The plane lifted a little as the heavy bomb dropped. For a few seconds there was no sound but the roaring of the motors, but then the reverberation of the explosion below reached them.
"Take a look below," said Davis, banking the machine sharply and beginning to swing in a narrow circle.
Gerrod looked down. He saw what seemed to be a ring of yellowish smoke, and a dark-blue spot in the middle of the silvery mass beneath them.
"It did something," he reported, "There's a dark spot on the surface. I can't judge how large it is, though."
Davis released a second bomb, and a third. Gerrod could watch them as they fell. They dwindled from winged, pear-shaped objects to dots. Then there was a flash far below and a spurting of water and spray. In a moment that had subsided, and he saw a second and larger dark-blue spot beside the first.
"I believe you've done it," said Gerrod excitedly. "You've certainly destroyed the silvery appearance. Dare you go lower?"
"Surely," said Davis cheerfully. The plane dived like an arrow, and flattened out barely five hundred feet above the surface.
Gerrod examined the dark spots through glasses. The disturbance had not completely abated, and he could see indubitable waves still radiating from the Spot where the bombs had fallen. Davis grinned like a boy when Gerrod told him.
"We'll land in the open space and make sure," he said suddenly, and the plane dived again.
Before Gerrod could protest they were just skimming the surface of the silver sea. The plane settled gently into the now liquid spot of ocean, and Davis shut off the motors. The occupants of the cabin looked eagerly out of the windows. All about them, in a space perhaps sixty or seventy yards across, the water was yellowed and oily, but was certainly water, and not the horrible, jellylike stuff the world had so much cause to fear. The concussion from the high-explosive bomb had shattered the fragile shells of the silver animalcules, and, with their protection gone, they had relapsed into liquid. At the edge of that space, however, the silver-sea began again, as placid and malignant as before.
The plane floated lightly on the surface while the little party congratulated itself.
"It works," said Davis proudly. Nita squeezed his hand ecstatically.
"I knew he'd think of something," she announced cheerfully.
Evelyn and Gerrod were estimating the area of cleared water with gradually lengthening faces.
"Let's see how much space a hand grenade clears," suggested Evelyn thoughtfully.
Davis opened the case and took out one of the wicked little bombs. He wriggled through a window and out on the massive lower plane of the flying boat. Balancing himself carefully, he flung the grenade some sixty yards into the untouched silver sea. It burst with a cracking detonation and amid a fountain of spume and spray. The four of them eyed the resultant area of clear water.
"How wide do you suppose that is?" asked Gerrod rather depressedly.
"Ten—no, fifteen yards by fifteen."
So excited were they all that they did not notice a phenomenon that began almost instantly. The tiny animalcules that formed the silver sea reproduced rapidly when given merely moisture. Here they had that moisture, and, in addition, the bodies of all their dead comrades to feed upon. The conditions were ideal for nearly instantaneous reproduction. As a result the waves from the high-explosive bombs had hardly subsided when the open space began, almost imperceptibly, to be closed by fresh masses of the Silver Menace. The open space became covered with a thin film which became thicker—thicker——
"And how much explosive was in that grenade?"
"Two ounces of TNT." Davis began to catch the drift of the questions, and his happy expression was beginning to fade away.
"Two ounces of TNT cleared up roughly a hundred and fifty square yards of silver sea. That's, say, seventy-five square yards to the ounce of high explosive." Evelyn was working rapidly with her pencil. "That works out—five hundred pounds of TNT needed to clear a square mile of the Silver Menace. We have fifteen hundred miles of coast that has been invaded to an average depth of at least five miles."
Gerrod took up the calculations with a dismal face. His pencil moved quickly for a moment or so.
"We'd need over eighteen hundred tons of TNT to clear our coasts," he said dolefully. "That wouldn't touch the silver sea itself or keep it from growing again. It grew inland those five miles in two weeks at most. That's nine hundred tons a week needed to hold our own without attacking the silver sea at all. We'd have to have forty-six thousand tons a year to hold it, let alone go after the beasts out here, and in the meantime we'll have no rain, consequently no crops. It's a cheerful outlook."
They had been oblivious of what was happening immediately about the seaplane.
Nita first saw the danger.
"Look!" she gasped.
They had been too much absorbed in gloomy thoughts to notice their predicament. The open space in which they had landed was now a shining, glittering mass of the Silver Menace. But what Nita pointed to was of more imminent danger. The sticky, horrible mass was creeping up the float on which the seaplane rode and up the smaller floats at the ends of the wings. Tons of the silver horror had already accumulated upon the under surface of the great planes and weighted down the aëroplane until it was impossible for it to rise in the air. And it continued to creep up and over the body. In a little while the seaplane would be overwhelmed by the viscid, evil-smelling, deadly little animalcules.
CHAPTER VII.
Shining slime crawled up the small floats at the ends of the lower wing. It crept along the under surface, and then dripped in thick ropes down to the surface below. When contact was established the ropes grew fat and wider, until they were like shining columns from the silver sea to the now heavily weighted plane. The disgusting stuff crept over the edges of the lower plane, and began to spread over its upper surface. Other masses began to creep up the struts that separated the lower plane from the top.
The three men began to work like mad. They tore strips from the roof of the cabin and began feverishly to scrape off and thrust away the insistently advancing enemy. The plane was a large one, however, and no sooner had they scraped clear one portion of the plane than another portion was covered even more thickly than the first. The cabin itself began to be attacked. Its lower portion already glistened like metal, and in a little while the silvery film began to cover the glass of the windows. Nita began to be frightened. Parts of the roof had been torn away to provide the three men—Davis, Gerrod, and the engineer—with the means of fighting the creeping horror. When the slime reached the roof and began, to pour down the opening there, the whole cabin would become a terrible, suffocating tank of the horrible stuff. Evelyn spoke quietly, though with a white face.
"If you start the motors the wind from the propellers may blow the jelly away from the cabin."
The engineer leaped to one of the propellers and swung his weight upon it. The engine turned sluggishly, and then coughed. A second desperate heave. The motor began to run with a roar. The surface of the slime on which the blast of wind beat shivered, and then reluctantly began to retreat. The second motor burst into bellowing activity. The whole plane began to shiver and tremble from the efforts of the powerful engines to draw it forward, but the jelly in which it was gripped still held it fast. The three men redoubled their efforts, and now some faint result began to show. Hampered by the vibrations which strove to shake it off, the Silver Menace advanced less rapidly. In half an hour the upper surface of the plane was nearly free. There was nearly a solid wall of silver horror connecting its under portion with the jellied ocean below.