Steam-ships

by R. A. Fletcher

The only ship of her kind ever built with a hot-air engine was the Ericsson, named after her inventor and generally called the Caloric, because of her peculiar engines. These had four immense cylinders which drove paddle-wheels 32 feet in diameter, the energy being transmitted by a contrivance Ericsson invented and termed the “regenerator.” The shape of the furnaces and the small amount of fuel they required, together with the absence of boilers, enabled a greater amount of space to be devoted to the accommodation of merchandise and passengers. The vessel was 250 feet long, 40 feet broad, 31 feet deep, and had a gross tonnage of 1920. She was built in 1852, of wood, and was asserted to have made a speed of 12 knots an hour on her trial trip, but she never came anywhere near this subsequently.

The absence of funnels and the presence of two large paddle-boxes made her one of the most extraordinary vessels ever seen. She made one slow journey across the Atlantic to Liverpool and back to America, and after another set of caloric engines had been tried in her with about as much success, in regard to her speed, as the first, she was fitted with engines of the ordinary type.

Three other inventions which have not yet passed the experimental stage are the Hydrocurve, the Hydroplan, and the Hydroplane.

The hydroplan is a motor-boat carrying two enormous propellers, one above the stem and the other above the stern, which revolve in the air and not in the water. The vessel is said to have been invented by a gentleman named Fortanini, and with a 70-horse-power motor is claimed to have attained, on Lake Maggiore, two or three years ago, a speed of 40 miles an hour. For all practical purposes the hydroplan may be described as a “skimming dish” hull gliding on the surface of the water, its draught being a few inches only.

For some time past some attention has been directed to the trials, on the Illinois River, of a curious type of aquatic motor, named the hydrocurve. Instead of ploughing through the water, the hull of the hydrocurve displaces the water, not sideways as with an ordinary type of vessel, but downwards from the surface, each particle of water being moved in one direction only. According to a report published in the Popular Mechanic of Chicago, this curious vessel on her first trial made a speed of 35 miles an hour. In a further test she achieved 1¹⁄₈ mile in 1 minute 30 seconds, or, roughly speaking, 45 miles an hour. She is 40 feet in length and carries an 80-horse-power motor. The bottom of the boat is concave, lengthways and across.

The theory that with an increase in speed the tendency of a ship is to rise, so that when travelling at a fast rate she will draw less water than when going slowly, and consequently will have less resistance and less skin friction, has attracted the attention of naval architects for many years. So far as theory is concerned, there is nothing to prevent a vessel being built on this principle, but when it comes to considering stability, it is another question altogether. The principle is based upon the well-known theory that if the hull of a vessel be made flat in the bottom and inclined slightly, so that it forms an inclined plane, the vessel will rise to an extent governed by the speed at which it travels. The Rev. C. M. Ramus, of Rye, Sussex, in 1872 improved on this theory by making a flat bottom in two inclined planes, one behind the other, so that each should have an equal lifting power. The Admiralty tested several models made by him, but without satisfactory results, probably due to the comparative inefficiency of the screw-propelling machinery of the period. An American engineer, named Fauber, taking advantage of improved propelling machinery, designed a vessel on these lines with hydroplanes attached directly to the bottom, and a year or two ago it carried six persons at a speed of 35 miles per hour. If a vessel of this size can be constructed and retain its stability, there is no reason why one of much greater size should not be built. The development of the principle is that the planes should be placed at some distance below the bottom of the hull, so that when the vessel travels at a considerable speed, it shall rise out of the water and be supported by the planes, which shall skim along the surface. This, however, can only be achieved at present by sacrificing stability to speed. An improvement in construction is to shape the bottom of the hull like a very wide letter V, with a series of planes underneath. It is claimed that an ocean liner can be built on this system, carrying six propellers arranged in three pairs, and that the necessary air would be pumped under the vessel by the action of the propellers as she travelled along.

A steamer on wheels, but intended to travel on the water, was invented a few years since by a Frenchman named Bazin. He constructed a model, which worked well and was on the scale of one-twenty-fifth of the liner he hoped to see built some day. The model consisted of four pairs of hollow wheels or discs, each wheel being in appearance like two immense soup-plates set face to face and set on edge. These wheels were caused to revolve, thereby reducing the friction of the water to a minimum, and the vessel was propelled by a screw. The decks, being built on a framework over the axles, had space for ample accommodation, and in order that the speed of the ship should not suffer it was intended to carry no cargo. A vessel on this plan was constructed and launched on the Seine. The platform was 126 feet long by about 40 feet wide, and each wheel was about 32 feet in diameter and about 10 feet at its greatest width. The total weight of the boat was about 280 tons. The boat proved her utility when tried. The inventor estimated that an ocean-going liner constructed on this system would easily cross the Atlantic at a rate of thirty knots an hour.

It is impossible to say what the development of the steam-ship will be in the future. The piston engine has probably reached its utmost development, or very nearly so, and much more in that direction is not to be expected. Naval architects are already considering whether the existing lines of the steam-ship are the best for speed, and a design has been brought out for a steamer constructed on what are known as tetrahedral lines. There has recently been described in the Scientific American a vessel, a model of which has been constructed, designed upon this tetrahedral principle. It is contended that this form for ships offers less resistance than any, and that by it alone can the greatest attainable speed at sea be reached. Yarrow boilers with Schultz turbines are recommended for vessels of this type.

A proposal for fast Atlantic travelling, which has not gone beyond the paper stage, is that three long narrow hulls should be built parallel to each other and supporting the main body of the hull. The inventor claims that the method would enable a greater speed to be attained than by any existing liner, and at a less cost; but readers who have followed the development of the steam-ship will recollect that this suggestion provides a curious parallel to the experiments of Patrick Miller with his triple-hulled boats in the eighteenth century.

Few, however, will doubt that, great as have been the changes in shipbuilding and steam-propulsion during the last hundred years, there will be changes as great in the present century.