Daniel set the leaf down and gazed out the window for a time. After several minutes had gone by, his eyes were drawn to a tiny movement in the front of the Tatler-Lock. Something had changed in one of the upper windows. He rose slowly to his feet, not daring to take his eyes off of it; for so vast and various was the prospect of London, the Pool, and the Borough from these windows, that this iota was as easy to lose as a single bubble on a stormy sea. To get the perspective-glass extended, aimed, and focused took entirely too long. Nevertheless he was able to get a clear view of a window, mostly veiled behind canvas, but with a human arm, seemingly disembodied, projecting across the front of it and gathering it out of the way (he supposed) so that some light might spill into the room behind. The arm was attached, in the customary manner, to a man, who was standing in the room with his back to the curtain and had hooked his elbow round the edge of the canvas to pull it aside. Presently that man let his hand drop. His arm vanished as the curtain tumbled back to block the whole aperture of the window. At this moment, many a chap would have glanced away to say something to the others, and thereby lost track of which window he’d been gazing at; but Daniel, out of a mental discipline earned fifty years ago, remained still until he had memorized certain peculiarities of the Window in Question: the way a seam in the canvas angled across the upper right corner, and a pair of bricks in the sill that were not as dark as the rest. Only then did he begin to swing the telescope laterally, causing the image to sweep at greatly amplified speed. He counted the windows to the edge of the building—three—then reversed the movement and made sure he could find the Window in Question again. Only then did he withdraw his eye from the lens and announce to the others that he had seen something.