Ghosts of Engines Past by Sean McMullen

sufflator forced the water in the right impeller pipe down and back, like a piston of water. After some moments there was a bubbling chuff as the last of the water was driven from the right pipe and the steam began to escape.
    “Heartbeat, dexter to sinister!” ordered Tordral, and the gatemen reversed the settings of the water and steam gates. Water poured into dexter pipe at the bow while steam forced water from sinister pipe at the stern.
    “Steam warden, call the heartbeats in my place,” ordered Tordral.
    “Master, is it wise to run with the patron sufflator not yet steaming?” asked Guy as he joined Tordral.
    “La Hachette's impeller can take her a mile and a half without the need of new hot water injected from the patron.”
    “Movement, and from air, water, fire and earth dancing in harmony,” said Renard dreamily. “Glorious.”
    “We may be twisted and thorny, but what clever folk are we?” added Tordral. “A steam impeller, two score times stronger than a sufflator's jet. In all the history of the world, no ship has ever been moved thus. We can reach Faerie... and we have a bombard.”
    “Why did we never share this wonder with Sir Gerald?” asked Guy. “We should have told him the truth.”
    “He was just one of many we lied to. Until an hour's half ago only the six of us doing the trials knew the truth.”
    “But he—”
    “We told lies to our friends so that they would be passed on to our enemies. I thought they would ensnare and englamour Gerald. Instead, Ivain was first, and he babbled nonsense about a steam bombard to them. Thus they thought us twisted, but harmless. Twisted, yes. Harmless? Not if we can make La Hachette's heart beat of its own accord, with no gatemen.”
    “Does La Hachette really need her own heartbeat?” asked Guy. “The mechanism functions when gatemen work it with their hands.”
    “Their hands are vulnerable to Faerie's glamours, Guy. The impeller must function without any hand upon it. We know there is a wide, dead space beyond the portal, both Renard and Jon saw it when they were returned. Without elvin spells to protect us, we mortals collapse there, our muscles flaccid. Unless La Hachette can travel the portal's span unaided, she will lose way and stop.”
    “And then?” asked Grace from the darkness.
    “We would be marooned in the borderlands between worlds, unable to move, starving to death.”
    “Don't fancy that,” said Grace, who was a veteran of many tavern brawls. “Rather die fightin'.”
    “Nobody will die,” said Tordral. “If La Hachette's heart cannot be made to beat, we shall not assail any portal.”
    “But then Sir Gerald will surely kill us for deceivin' him.”
    “Oh no, I have one last trick for Sir Gerald—but enough gloom, we have a lady who needs a heart. Guy, explain the problem to those new to our secret. Someone may have a suggestion.”
    “When steam strokes end, the steam gates don't drop with enough force for the tag levers to trip their sister steam gates and the two water gates. Without gatemen, the heartbeat cannot be passed from dexter to sinister and back again.”
    “To me it seems little force was needed,” said Renard. “Have the gates never tripped of their own accord?”
    “Once, yes,” said Tordral. “With lead weights on the trip levers, the gates were indeed forced to open and close by the extra impetus from the weights' motion.”
    “But there is a delay of one fifth of the impeller's heartbeat, due to the extra time the lever takes to swing when weighted,” explained Guy. “In that time La Hachette is without the impeller and has no impetus. She would stop.”
    For a time there was silence, except for the clank-clang, hiss, chuff as the gatemen worked La Hachette's mechanical heart.
    “Can someone explain something nautical to a poor, ignorant French sergeant who knows only bombards?” asked Renard.
    “And English women, English ale, English—” began Ward.
    “Let him speak!” called