CHAPTER VIII.
Nita was clinging to Davis' hand as they drove out to the Gerrods' cottage again. Traces of her fright still lingered on her face, and Davis' hand was comforting. Gerrod and Evelyn were silent and discouraged. The only really promising plan for fighting the Silver Menace had proven so ineffectual as to be practically useless. In silence the little motor car wound along the twisting road to the little cottage.
All of them were quiet, even gloomy, as they sat down to lunch. Evelyn tried to talk lightly, but conversation lagged in spite of her efforts. The maid brought in their dishes and removed others without a sound. None of them could eat more than a very little.
When the meal was finished Gerrod and Evelyn went out on the porch to discuss gravely the chances, even now, of producing the explosive needed to hold back the Silver Menace. The almost instantaneous reproduction that had taken place over the cleared area at sea, however, made it evident that nine hundred tons of explosive would be needed, not every week, but every day. All the factories in the country, working at their highest speed, could not supply the quantity necessary.
Davis went into the laboratory and brought out one of the silvery test tubes of animalcules.
"Nita," he said mournfully, "I've fought Germans and come out on top. Gerrod and I fought Varrhus and won out. But these infernal little animals, so small I have to take a microscope to see them, seem to have me beaten."
Nita's soft hand crept up and snuggled inside Davis' larger one.
"No, they haven't, either," she insisted stoutly. "You'll think of something yet."
Davis sighed.
"And it would be so perfect if we could be the ones to find out how to beat them," he said dolefully. "That would satisfy your father, and we'd have nothing else to worry about."
Nita looked up into his solemn face, and, in spite of herself, laughed.
"You're worrying too much," she announced. "We're going to take a vacation and go into the music room and I'm going to play soft music that will take your mind off your troubles."
She led him into the tiny music room of the bungalow, and sat down at the small grand piano there.
"You can turn over the music for me," she said gravely as she made room for him on the seat before the keyboard.
There was no music on the rack of the piano, but neither of them thought of that. Davis set down the test tube he had brought with him and prepared to listen. Nita quite forgot to play any recognizable melody, too. Davis thoughtlessly took possession of her left hand, so she idly struck chords with her right, while the two of them talked foolishnesses that were very delightful. They spoke in low tones, and their voices were soft. They were having an amazingly pleasant time.
They heard footsteps on the porch, and self-consciously drew apart. Gerrod and Evelyn were coming indoors to go back into the laboratory to work on wearily in hopes of stumbling on something that might have an effect upon the ever-encroaching Silver Menace. Davis hastily picked up the test tube full of animalcules. As he took it in his hands, however, he uttered an exclamation of astonishment. The contents were no longer silvery! The tube was full of water with a faintly yellowish tinge. Davis' jaw dropped.
"People!" he called hastily. "Come here! Something has happened!"
Gerrod and Evelyn appeared in the doorway.
"What's the matter?"
"Something's happened to these little beasts." Davis held out the test tube. "Twenty minutes ago this was full of the silver stuff. I put it down on the sounding board here and now they're smashed up and dead!"
Gerrod looked at the tube intently.
"Where was it?"
Davis showed him. Gerrod put one hand on the spot and struck a chord tentatively. His expression changed from weariness to hope.
"Wait a minute!" he exclaimed, and darted into the laboratory, to return a moment later with half a dozen test tubes full of the sticky animalcules. "We'll put another one there and strike a chord."
He did so. The contents of the test tube remained unchanged. He struck another. Still no change. Then, deliberately striking one key after the other, with the eyes of all four of them fixed hopefully on the test tube, he began to go up the keyboard. Note after note was struck, but just as they were about to give up hopes of finding the cause of the first tube's clearing Gerrod struck a key—the F above high C. The instant the shrill note sounded out the test tube clouded—and was clear! It had lain upon the sounding board of the piano. The vibrations of the piano string had been communicated to it through the sounding board.
"Done!" shouted Davis at the top of his voice.
Nita was speechless.
"Sympathetic vibrations," said Gerrod happily. "If you could hang up one of those microscopic shells and ring it it would ring that note. So, when the vibrations from the piano strike them, they vibrate in sympathy, only the piano vibrations are so strong and the shells so fragile that they rack themselves to bits, and the animals are killed. Whee! Hurray! Hurray!"
He shook hands all around, hardly, able to contain his excitement.
"But I say," said Davis anxiously, "will those vibrations travel through water, and can we put a piano overboard?"
Gerrod laughed.
"We'll put a submarine siren overboard," he said excitedly, "and tune it to that note. You can hear a submarine siren for fifteen miles with an under-water telephone. Man, you've done the trick!"
The maid appeared in the doorway.
"Some one on the telephone for Miss Morrison."
Nita reluctantly left the room where the others were chattering excitedly. She went to the telephone and put the receiver to her ear, still unconsciously trying to catch the words of the party in the music room. Almost the first words she heard drove them from her mind, however. Her father was speaking.
"Nita," he was saying coolly, "this is your father. I'm marooned in the house on the island, and the Silver Menace is climbing up the walls. The windows are blocked. I'm expecting them to break in any minute. When they do I'm done."
"Daddy!" Nita choked, aghast.
"Simmons, the chauffeur, tried to get across the bridge this morning," said her father still more coolly, "and the sticky stuff got him. The room I'm in is dark. The Silver Menace has climbed up to the roof. We've stopped up the chimney so it can't come down to get us, but when the house is completely covered we'll be in an air-tight case that will suffocate us sooner or later. I'm rather hoping the windows will break in before that time. I'd rather die like Simmons this morning."
"But, daddy, daddy, hold on! We'll come to you——"
"It can't be done," her father interrupted crisply. "I called you to say good-by and to tell you to look after the families of the servants that are fastened up here with me." He paused a moment, and said quietly: "I'm in the library downstairs. I can hear the windows creaking. They may give way at any moment and let the horror into the house. It tried to creep in under the doorsills, but we calked them with the table linen."