The _Nautilus_ of these inventors was submerged on the same principle as the boat of André Constantin, viz., by the drawing in of cylinders. The submersion was effected by means of four-cylinders on each side of the vessel, which were drawn in flush and pushed out beyond the side, thus altering the displacement. The _Nautilus_ underwent some trials in Tilbury Docks in 1888, and the following account is from the pen of Mr. Bennett Burleigh: “A few years ago a gentleman invited a number of officials and specialists down to one of the London docks to see a new submarine boat, which, like so many gone before, was to achieve marvels. There were naval men and military men, and journalists there by the score. Among others were the present chief-instructor of the navy, Sir W. H. White, and Lord Charles Beresford. The writer was on board, but felt a strong natural disinclination to go below or permit any of his friends to adventure. It possibly was an excess of natural timidity. That craft was warranted ‘extra special safe.’ She had water tanks, a false keel that could be slipped off, and cylinders or drums which, pushed out or drawn in from her sides, added or took away from her displacement and buoyancy. Charming in theory, but hydrostatics present strange problems, so note the result. The boat, with Sir W. H. White on board, having made all tight, let water into her tanks, and sank into the profound oleaginous mud of the dock. She remained invisible beneath for a protracted period, greater, in truth, than those upon the dock knew was safe, for she had no air or oxygen storage. We could do nothing but wait and look at our watches. Finally, to everybody’s intense relief, she reappeared. It happened that the boat stuck in the mud, and neither sending out the drums nor unloading the tanks made her rise. Sir William White suggested, when the light was turning blue, as were some faces, moving the crew to the higher end of the craft. It had the desired effect, the boat was lifted from the grip of the mud. Once on top, the engineer undid the manhole and shouted with elation to his friends ashore that they were going down again. Several of the visitors had had more than enough, and the gentleman was pulled down by the legs to make way for those who wished to escape upon deck and reach _terra firma_. That ‘famous’ submarine craft also followed the course of its predecessors, and shortly after passed into the limbo of forgotten failures.” It appears that the cylinders declined to out-thrust because the power for working them, though amply sufficient for working in water, was not great enough to drive them into mud, and the inventors had not taken into consideration the adhesiveness of mud. [Sidenote: Waddington.]