“Well, that’s good of you. It would be a help if you would take the tiller while I’m making all snug. There’s a bit of a tumble on outside.” The boat was certainly a flier. The charmingly situated old town dropped rapidly astern while Lamson “made snug.” Then he came aft, shouted down through the engine room skylight for his friend, and when the latter appeared told him to take the tiller. “Now, Mr. Cheyne,” he went on, “now comes the great moment! I have not fixed the apparatus up here in front of the tiller, partly to keep it secret and partly to save the trouble of making it weatherproof. It’s down in the cabin. But you understand it should be up here. Will you come down?” He led the way down a companion to a diminutive saloon. “It’s in the sleeping part, still forward,” he pointed, and the two men squeezed through a door in the bulkhead into a tiny cabin, lit by electric light and with a table in the center and two berths on either side. On the table was a frame on the top of which was stretched a chart, and a light rod ran out from one side to a pointer fixed over the middle of the chart. “You can see that it’s very roughly made,” Lamson went on, “but if you look closely I think you’ll find that it works all right.” Cheyne bent forward and examined the machine, and as he did so mystification grew in his mind. The chart was not of the estuary of the Dart, nor, stranger still, was it connected to rollers. It was simply tacked on what he now saw was merely the lid of a box. How it was moved he couldn’t see. “I don’t follow this,” he said. “How do you get your chart to move if it’s nailed down?” There was no answer, but as he swung round with a sudden misgiving there was a sharp click. Lamson had disappeared and the door was shut! Cheyne seized the handle and turned it violently, only to find that the bolt of the lock had been shot, but before he could attempt further researches the light went off, leaving him in almost pitch darkness. At the same moment a significant lurch showed that they were passing from the shelter of the estuary into the open sea. He twisted and tugged at the handle. “Here you, Lamson!” he shouted angrily. “What do you mean by this? Open the door at once. Confound you! Will you open the door!” He began to kick savagely at the woodwork. A small panel in the partition between the cabins shot aside and a beam of light flowed into Cheyne’s. Lamson’s face appeared at the opening. He spoke in an old-fashioned, stilted way, aping extreme politeness, but his mocking smile gave the lie to his protestations.