Emilie & the Hollow World by Martha Wells

uncertainly. “Your crew weren’t eager to travel to our world, were they?”
    Kenar rubbed his eyes. With the scales and the fur, it was hard to see how affected he was, but Emilie thought his shoulders were tense and his usual calm self-possession was gone. Sounding a little exasperated, he said, “Not at all. Until we met Dr. Marlende and his crew, we thought your world a legend. We have our own concerns here. They could spare me for a brief visit, to help pay our debt to Marlende, but there is just no reason the others would make the trip.”
    Captain Belden said, “Dr. Marlende could have left with the airship, and something attacked the ship's crew before they could leave the island.”
    Emilie saw Kenar's jaw tighten at the thought. Miss Marlende sat forward impatiently. “This kind of speculation is useless. Our assumption must be that someone or something attacked the island, and both crews were forced to flee in the airship.”
    Kenar looked up, his expression thoughtful, and Emilie found herself nodding. If something like the Sargasso creatures, or worse, had attacked, the airship would be the quickest way to escape. “The airship might have run out of fuel then, and be stuck on another island,” she said.
    Captain Belden frowned at her, as if he didn't think she should be giving her opinion, but Miss Marlende said, “Yes, that could very well be it. The question is, how do we find them?”
    “There hasn't been a peep out of the wireless, not that it's supposed to be much use down here,” Oswin said, sounding glum. “We can't track them through the air or the water. It's not as if they'll have left tracks.”
    Abendle cleared his throat. “They might have.”
    Intrigued, Lord Engal twisted around to stare at him. “Yes? Speak up, man.”
    Abendle stepped forward, seeming uneasy with all the sudden attention, but he said, “Aetheric engines do leave tracks, My Lord, when they aren't traveling through aetheric currents.”
    “But the airship's aetheric engine was damaged.” Miss Marlende looked uncertainly from Abendle to Dr. Barshion. “They shut it down to use the airship's conventional engine.”
    “If it's even them still running the airship,” Oswin said. “If something didn't attack both crews to steal it.” Captain Belden nudged his shoulder in silent remonstrance.
    Emilie didn't think Oswin was speaking out of turn. There was surely no one on the ship who hadn't considered the possibility that the Cirathi crew, and Dr. Marlende and all his men, might be dead or captured by something. It was an awful possibility, but it was still a likely one.
    “Aetheric engines can't ever really be shut down, once they're started up,” Abendle explained. “The aether that powers them is still active, still producing power, and connecting with the aether in the air, if you see what I mean, even if the motile itself is not being used to draw the vehicle along an aetheric current. It's as if it pulls bits of aether into itself, and leaks bits out as it moves along. Like a normal engine will leak oil. Those bits will be clumped up, so to speak, much thicker than the normal concentrations of aether in the air.” He appealed to Dr. Barshion. “Isn't that true, sir?”
    Everyone turned to Barshion. “Well, yes,” he admitted reluctantly. “It's a possibility. But I'm not sure how an aetheric engine would behave here, in this world. Its aetheric composition is different from our own, you know.”
    Kenar was sitting up straight, listening intently. He looked hopeful for the first time since they had seen the empty Cirathi ship. Miss Marlende said, “We can try, surely.”
    Emilie eyed Barshion, not sure why he was so reluctant. It's not as if we have a lot of other pressing things to do while we wait for him to fix our aetheric engine, she thought. Everyone else, even Lord Engal, seemed game to go on with the search.
    “Yes, how would this be accomplished, Barshion?” Lord Engal said. “There should be