It was during his stay on the _Mary Ellen_ that Dave first learned, under the personal supervision of Captain Grummitt, who spent most of his time on the bridge, the art of taking a trick at the wheel. And during those watches in the little, boxlike wheel-house the boy also learned many other things appertaining to the ways of ships, for Captain Grummitt took a great interest in the lad. The time was not far distant, moreover, when Dave was to be thankful for such lore as he gathered from the portly old sea-dog. Life on the tug was by no means devoid of its adventurous side. There were days and nights when the water was as calm as the proverbial mill-pond, and when the work of the _Mary Ellen_ could be carried on without excitement; but there were also times when nerves of iron were needed. Picking up casual sailing craft which needed a tow was child’s play compared with the _Mary Ellen’s_ task of taking a ship under its sheltering wing on a dirty night. The worse the weather was, the more likely the tug was to be needed outside the entrance to the harbor, and the skipper took a grim pleasure in riding out a gale when other craft found it prudent to take shelter. One wild night, when Dave had been on the tug about a month, even the skipper was thinking of getting under the shelter of the Bluff, for the _Mary Ellen_ was tossing about so heavily that her crew could barely keep their feet, and more than one hissing comber had deluged the deck. Rain was falling in sheets, and it was the darkest hour of the night. Dave was on duty with Grummitt in the little wheel-house. The tug was right in the track of all incoming vessels, but few passed, except one or two dark forms of steamers laboring along like gray ghosts of the ocean. “It’s a rare night for trouble,” Captain Grummitt said, “but I think this is where we get under the lee of the land for a spell.” Still he kept his hand off the engine-room telegraph. Once or twice during the last quarter of an hour he had been peering through his night glasses away to the southeast. “Blow me if I didn’t see a light down that way,” he muttered. “Mebbe I’m beginning to fancy things in my old age. If only this rain would ease up for a minute―― Gosh! There it is again. Now what in thunder is up?” he said, suddenly moving the lever over to the signal “Full speed ahead.” The _Mary Ellen_ plunged forward, rolling over at a terrific angle as the heavy seas struck her port beam. “What do you make of it, Cap’n?” Dave asked. “Dunno.” Captain Grummitt was scratching his pate in perplexity. “She doesn’t seem to have shifted for a long while, so I guess we’ll just find out.” Ten minutes’ run brought them near enough to see what was happening. A large Swedish sailing ship, with poles bared, was riding uneasily at the stern of a tug. Apparently they were making no progress.