Experiments with this style of river craft have been frequent on both sides of the Atlantic without, however, being followed by substantial success. So long ago as 1835, the _Rapid_, consisting of two hollow cylinders, pointed at either end in cigar fashion, placed ten feet apart, with a large wheel between them in the centre, appeared on the Upper St. Lawrence, fitted with the steam-engine of the superannuated _Jack Downing_. Her first trip down the river was also her last, for, after many fruitless attempts to return, she was wrecked, and for a time abandoned. Eventually, she was towed, by way of the Ottawa and Rideau canals, to Ogdensburg, where she was refitted and plied for some time as a ferry boat. A very pretty specimen of a cigar-boat built of iron, with an elegant superstructure, the writer remembers having seen on the Clyde more than half a century ago, but as to its career and ultimate fate deponent sayeth not. A twin-boat steamer, reminding us of Patrick Miller’s first attempt at steam-boating, propelled, however, by side-wheels, may be seen any day during the season of navigation dragging its slow length along on the ferry from Laprairie to the opposite shore of the St. Lawrence, near Montreal. VI. THE ROLLER STEAMBOAT. The reader is requested to put on his thinking cap before endeavouring to comprehend the brief reference now to be made to Mr. Knapp’s “Roller.” On the 8th of September, 1897, there was launched from the yard of the well-known Polson’s Iron Works Company in Toronto, an enlarged model of the strangest craft ever seen—a huge innovation upon all preconceived ideas of marine architecture. The exterior of the boat in question, if it can be called a boat, has all the appearance of a round boiler 110 feet long and 25 feet in diameter. The outer cylinder is built of one-quarter inch steel plates stoutly ribbed and riveted, and armed with a number of fins, or small paddles, the ends being funnel-shaped, with openings in the centre. This is made to revolve by means of two engines of 60 horse-power each, placed one at either end of the vessel. An inner cylinder similarly constructed, corresponding to the hold of a ship, remains stationary while the other is supposed to be rolling over the surface of the water, regardless of wind and waves, at railway speed. The modest calculation of the inventor is that a steam vessel so constructed of 700 feet in length and 150 feet in diameter, _ought_ to cover the distance between New York and Liverpool in forty-eight hours! This model was built at a cost of $10,000. The results of the trial trip on Toronto Bay have not been made public. VII. THE “TURBINIA.”