The Borrowers Aloft by Mary Norton

worthwhile day," said Pod.
    But by the time they had gone through the elaborate process of closing up the window and had hidden all traces of the recent experiment below the floor board, they were utterly worn out. It was not yet dusk before they crept wearily into their blanket-lined box and stretched their aching limbs.
    By the time Mr. and Mrs. Platter brought their supper, all three were lost to the world in a deep, exhausted sleep. They did not hear Mrs. Platter exclaim because the fire was out. Nor did they see Mr. Platter, sniffing delicately and peering about the room and complaining that "You ought to be more careful, Mabel—there's a wicked smell of gas."
    Mrs. Platter, very indignant, protested her innocence. "It was you who lit the gas fire this morning, Sidney."
    "No, that was yesterday," he said. And as each knew the other (when caught out in misdoing) to have little regard for truth, they disbelieved each other and came to no conclusion.
    "Anyhow," Mrs. Platter summed up at last, "the weather's too mild now for gas fires..." And they never lit it again.

Chapter Twenty
    The next ten days were confined to serious experiment, controlled and directed by Pod. "We want to go at it steady now," he explained. "Keep to a program, like, and not try too much at a time. It's a big undertaking, Homily—you don't want to rush it. 'Step by step climbs the hill!'"
    "But when do they open, Pod?"
    "Riverside Teas? April the first, if the cage-house is finished."
    "I'll wager it's finished now. And we're getting well into March..."
    "You're wrong, Homily. They've not delivered the plateglass nor the handle to lift it up with. And something went wrong with drainage. They had a flood, remember? Didn't you listen when they were talking?"
    "Not if they're talking about the cage-house I don't listen," said Homily. "It gives me the creeps to hear them. Once they start on about the cage-house, I go right under the blanket."
    During these busy ten days, Pod and Arrietty walked about so much on the open pages of the Illustrated London News that the print became quite blurred. They had to discard the idea of a valve at the top of the canopy to be controlled from below by a line that passed through the open neck into the basket because, as Pod explained to Arrietty, of the nature of the canopy. He touched the diagram with his foot. "With this kind of fabric balloon, you can have the valve line through the neck.... But rubber's like elastic; squeezes the gas out.... We'd all be gassed in less than ten minutes if we left the neck open like they do."
    He was disappointed about this because he had already invented a way to insert a control valve where it should be—in the top of the canopy—and had practiced on the smaller balloons of which they had an endless supply.
    In the meantime, as Homily with a needle ground down by Pod worked on the shaping of the net, he and Arrietty studied "equilibrium and weight disposal." A series of loops was made in the towline on which—once the balloon was inflated—they would hang up various objects: a strawberry basket, the half-shaped net, a couple of keys, a hollow curtain ring, a tear-off roll of one-and-sixpenny entrance tickets to Ballyhoggin, and lastly they would swing on the line themselves. There came a day when they achieved a perfect balance. Half a dozen one-and-sixpenny entrance tickets, torn off by Arrietty, would raise the balloon two feet; and one small luggage key, hooked on by Pod, would bring it down with a bump.
    Still, they could find no way of controlling the gas through the neck. They could go up, but not down. Untying what he called "the guard knot" at the neck—or even loosening the guard knot—would, Pod thought, be a little too risky. The gas might rush out in a burst (as they had seen it do so often by now), and the whole contraption—balloon, basket, ballast, and aeronauts—would drop like a stone to the earth. "We can't risk that, you know," Pod said to Arrietty. "What