While Ericsson, Smith, Woodcroft and Lowe were busying themselves with experiments for perfecting the principle of the submerged screw as a means of propelling vessels through the water, another plan was being devised which, for a time, excited much interest, and was very nearly becoming a success. This was Ruthven’s water-jet propeller. It differed from Ericsson’s in the singular fact that the actual propeller was placed inside of the ship instead of on the outside. This propeller, in the shape of a fan-wheel with curved blades, was made to revolve horizontally and rapidly in a tank of water placed in the hold of the vessel, fed from the sea through openings in the hull. The power of the steam-engine was applied to expelling the water from this tank through curved pipes with nozzles, on either side of the ship. In proportion to the velocity with which the water was forced through these pipes into the sea below the water-line, an impetus in the opposite direction was given to the vessel. The nozzles were so constructed that they could be turned easily towards the bow or stern, as occasion required, for forward or backward motion. The first experiment with this appliance was made by Messrs. Ruthven, of Edinburgh, on the Frith of Forth, with an iron boat 40 feet in length, in 1843, when a speed of seven miles an hour was attained. The _Enterprise_, 90 feet long and 100 tons burthen, was built on this principle, and made her trial trip, January 16th, 1854, when she developed a speed of 9.35 miles an hour. This vessel was intended for the deep-sea fishing, and the jet-propeller was suggested in this case as being less liable to become entangled with the nets than the screw or paddle. The water-jet system was also tried on a Rhine passenger steamboat with some measure of success; but while the theory was upheld, it seems to have failed in practice, because the results in speed and in other respects were not proportioned to the working power and the consumption of fuel. See _En. Britannica_, 8th ed., vol. xx., p. 661. V. THE CIGAR STEAMBOAT.