Mina Wentworth and the Invisible City by Meljean Brook

you ever heard of or seen a machine that looks like a six-foot-tall brass wheel that rolls along by itself?”
    He frowned. “No.”
    “Did you stay inside the house with Redditch?” The butler had said they’d remained in the library, but perhaps he and Redditch had gone into the garden through the library doors without drawing notice.
    “Yes,” he said. “In the parlor, then the library.”
    “Did you ever go outside?”
    “Not until I left.”
    “Which door did you leave by?”
    “The front.” A brief, hard smile touched his mouth. “He was trying to butter me up, remember. And I might smell like a match factory, but I’m not a servant.”
    “All right.” She shot a glance at Newberry to see if he had anything to add. With a tiny shake of his head, the constable replied that he didn’t. “Thank you, Mr. Foley. Please contact me if you recall anything else during your time at Lord Redditch’s home, even if it seems insignificant.”
    “I will.”
    Almost everyone on the work floor glanced up as she and Newberry left Foley’s office. How many of them would be put out of work? Whether Foley brought the automatons in or continued on as he was, it seemed that half of them—at the very least—would soon be looking for another way to earn a wage.
    That fear might give someone motivation to kill. If Redditch’s bill had passed and Foley wasn’t able to install his machines, he’d lose his factory.
    It was a reason to kill . . . but she didn’t see it in Foley. He’d seemed resigned, but not yet desperate. Mina would keep him in mind, though—and also look at anyone else who might have been threatened by Redditch’s bill.
    Hopefully, she would find a substantial lead before that, however. Redditch’s body might give her one when they returned to headquarters. Tomorrow, they’d return to Portman Square and knock on doors again—asking about the wheel, but also about a lorry waiting in the alley or the street that might have taken it away. In that area, that early in the evening, someone had to have seen something. That wheel hadn’t simply disappeared.
    But their front tires had.
    Mina stopped outside the factory door, heard Newberry’s quick breath as he halted behind her. In the middle of the yard, the police cart sat with its nose in the ground. She pursed her lips.
    “I did double-lock them, sir.”
    “I know it, constable.” Her reliable assistant wouldn’t have forgotten. “I was just thinking what a lovely night it is for a walk. Don’t you agree?”
    His red mustache twitched when he smiled. “The evening is rather pleasant, sir.”
    “It is settled, then. I had planned to return to headquarters and examine Redditch’s body, but I think we shall have a little stroll to the London Bridge, where we will find us each a cab to take home. We will meet at headquarters two hours before shift tomorrow morning, instead. The body can wait for us that long.” She felt a bit of relief when Newberry unlocked the boot. At least the thieves hadn’t taken their equipment. “I’ll carry the kit if you will carry the camera, constable.”
    “I can carry them both, sir.”
    “Don’t be absurd, Newberry.” The ferrotype camera assembly weighed as much as Mina did, and the trunk containing their kit half as much. Strengthened by her bugs, she could easily manage either one, and there was no sense in him trying to balance both. “We are in luck that the bridge is not far, and that it is not a repeat of our hike in the rain from Chiswick.”
    With his head in the boot, she couldn’t clearly hear his reply, but she thought Newberry might have groaned at the reminder. They had not exactly hiked—“waded through knee-deep mud” would have been more accurate, and considering the number of cows grazing alongside the road, Mina wasn’t certain that “mud” was accurate, either.
    He straightened, the camera assembly cradled in his big arms. “Very lucky, sir.”
    She reached in for the kit,