At last, on the 10th of August, about five o'clock in the afternoon, the last squadron of the rear-guard cantered over the hills west of Morteyn, and the last straggling Uhlan followed after, twirling his long lance.
Every day Lorraine had watched and waited for one word from her father; every day Jack had ridden over to the Château de Nesville, but the marquis refused to see him or to listen to any message, nor did he send any to Lorraine.
Old Pierre told Jack that no Germans had visited the Château; that the marquis was busy all day with his machinery, and never left his turret except to eat at daylight in the grand salon below. He also intimated that his master was about ready to make another ascension in the new balloon, which, old Pierre affirmed, had a revolving screw at either side of the wicker car, like a ship; and, like a ship, it could be steered with perfect ease. He even took Jack to a little stone structure that stood in a meadow, surrounded by trees. In there, according to Pierre, stood this marvellous balloon, not yet inflated, of course. That was only a matter of five seconds; a handful of the silver dust placed at the aperture of the silken bag, a drop of pure water touched to it, and, puff! the silver dust turns to vapour and the balloon swells out tight and full.
Jack had peeped into the barred window and had seen the wicker car of the balloon standing on the cement floor, filled with the folded silken covering for the globe of the balloon. He could just make out, on either side of the car, two twisted twin screws, wrought out of some dull oxidized metal. On returning to Morteyn that evening he had told Lorraine.
She explained that the screws were made of a metal called aluminum, rare then, because so difficult to extract from its combining substances, and almost useless on account of its being impossible to weld. Her father, however, had found a way to utilize it—how, she did not know. If this ascension proved a success the French government would receive the balloon and the secret of the steering and propelling gear, along with the formula for the silvery dust used to inflate it. Even she understood what a terrible engine of war such an aërial ship might be, from which two men could blow up fortress after fortress and city after city when and where they chose. Armies could be annihilated, granite and steel would be as tinder before a bomb or torpedo of picric acid dropped from the clouds.
On the 10th of August, a little after five o'clock, Jack left Lorraine on the terrace at Morteyn to try once more to see the marquis—for Lorraine's sake.
He turned to the west, where the last Uhlan of the rear-guard was disappearing over the brow of the hill, brandishing his pennoned lance-tip in the late rays of the low-hanging sun.
"Good-by," he said, smiling up at her from the steps. "Don't worry, please don't. Remember your father is well, and is working for France."
He spoke of the marquis as her father; he always should as long as she lived. He said, too, that the marquis was labouring for France. So he was; but France would never see the terrible war engine, nor know the secrets of its management, as long as Napoleon III. was struggling to keep his family in the high places of France.