A thread of gossamer now connected the steeples of St. Mary-at-Hill and St. Dunstan-in-the-East, and thence ran almost in a straight line to the roof of Trinity House. But haply he focused on the streaming gutter of Tower Street just in time to see a crossbow-bolt flying above it. This pierced the copper roof-skin of All Hallows Church. It had only lodged there for a few moments when a dark-skinned, barefoot man scrambled to it, and commenced a curious hand-over-hand pantomime. He was pulling in yards of silken thread, too fine to be resolved by the glass. It was originating from a smooth-rubbed copper vat on the roof of Trinity House, and it got thicker as he pulled it in, so that if one had the patience to stand there and watch, it might in the end become visible.