By this time they had come near enough to the end of the gallery to hear a persistent low hollow grinding and booming noise. Stubbs threw open a door at the end and led them into a spacious room—for they had entered into a sort of bastion anchoring the western end of the hospital, like the fist at the end of an arm—where that noise was a good deal louder. This salon was as cluttered with peculiar exhibits as the Court of Technologickal Arts at Clerkenwell, and as crowded with obstreperous madmen as a meeting of Her Majesty’s Privy Council. But the biggest object in the room—and the source of the noise—was an immense wooden drum, mounted above the floor like a wheel. Its axle spanned the interval between a pair of massive upright timbers, each of which rose to slightly above Daniel’s head. The drum was shaped like a fat coin, perhaps a yard thick. Its rim nearly grazed both floor and ceiling, which would make its diameter rather more than twelve feet. The circular faces of it—the heads and tails of the coin, as it were—had been fabricated in the same way as primitive cart-wheels, viz. of broad deals fastened side-by-side with long iron straps. The rim consisted of more planks pegged crosswise between these two disks.