boat either down or up.’ Similar hydroplanes, or horizontal rudders, appeared in the later Holland boats, and are now in common use in all submarine types. Lake was of British descent, his family having emigrated from Wales to New Jersey; but he owed his first interest in submarine construction, and many of his inventive ideas, to the brilliant French writer, Jules Verne, whose book ‘Twenty Thousand Leagues under the Sea’ came by chance into his hands when he was a boy ten years old, and made a lasting impression upon him. 2. _Stability._--Next to the power of submersion, the most necessary quality in a submarine is that of stability under water. The most obvious method of securing this is by water ballast, which was probably the first means actually employed. Bushnell, in 1771, substituted a heavy weight of lead, as being more economical of space and better suited to the shape of his boat, which resembled a turtle in an upright position. The leaden ballast, being detachable at will, also acted as a safety weight, to be dropped at a moment of extreme urgency. In the _Nautilus_, built in 1800 by the famous engineer, Robert Fulton, an American of English birth and education, the leaden weight reappeared as a keel, and was entirely effective. The inventor, in a trial at Brest in 1801, dived to a depth of 25 feet, and performed successful evolutions in different directions for over an hour. Bauer, fifty years later, returned to the ballast principle, and used both a water-tank and a safety weight in the same boat. The results were disastrous. His first submarine sank at her first trial in Kiel harbour, and was never refloated. His second was built in England; but this, too, sank, with great loss of life. His third, _Le Diable Marin_, after several favourable trials at Cronstadt, fouled her propeller in a bed of seaweed, and the releasing of the safety weights only resulted in bringing her bows to the surface. The crew escaped with difficulty, and the vessel then sank.