The engines of the Britannic are by Maudslay, Sons, and Field; they are 760 nominal, but indicated 5090 horse-power on the trial trip. They have four inverted cylinders, the high pressure above the low; the diameters of the cylinders are 48 inches and 83 inches respectively, and the length of stroke 5 feet. The pressure of steam is 70lbs. per square inch, and the boilers, eight in number, are fired at both ends with thirty-two furnaces. The propeller has four blades, and is 23 feet 6 inches in diameter, with 28 feet to 31 feet 6 inches pitch. The mode of lifting the screw is novel, as may be seen by [the drawing on the following page].
Details of Britannic, and form of her screw.
The plan is that of Mr. Harland, the senior partner of the firm by whom the Britannic was built. His reasons for introducing this new principle (which he styles, “a lifting-propeller”) are, that in long ships, the pitching in a heavy sea way and the vertical motion of the waves tend to expose the upper portion of the screw as usually fitted, the evil effects arising from this being the ‘racing’ of the engines and its attendant dangers, together with a diminished speed of the vessel.[260]
It is possible, also, that a further advantage may be derived from the fact that, as one-half of the propeller works below the vessel’s bottom,[261] there is a somewhat denser medium of water for it to work against, consequently affording (but to what extent, my limited scientific knowledge will not allow me to offer an opinion) the means of obtaining, as I conceive, an increased power of propulsion.[262] But into such questions as these I will not enter, as I prefer stating the facts and furnishing an account of what has been done, leaving others more competent than I am to deal with them. As scientific men may consider another question of still greater importance, the best form for the midship section of a steamship, to which I have already referred, I furnish (see [page 281]) a sketch, drawn to scale and supplied by her owners, of the midship section of this magnificent vessel, and, without further comment, give an account of her performances on her first voyage across the Atlantic.[263]
“The average speed of the Britannic is fifteen knots per hour on a consumption of 75 to 80 tons of coals per day, and her approximate cost, built without contract, is 200,000l.”[264]
These steamers run in connection with the Erie Railway from New York (as do also other of the lines) booking their passengers through to all parts of the United States, as far as Aspinwall and San Francisco, and also to Canada. As their arrangements and scale of provisions for steerage passengers are, in nearly all respects, the same as that of the other Transatlantic lines, a copy is furnished for the information of my readers, together with the conditions on which alone passengers are received.[265]
Difficulty of estimating the real cost of steamers.
Recently an American Company have with great spirit sent forth from their own country, a line of steamers to trade between Philadelphia and Liverpool.[266] They consist at present of the Pennsylvania, Illinois, Ohio, and Indiana, each of about 3100 tons gross, or about 2000 tons nett register; they are all built of iron, on the Delaware (U.S.), and are fitted with screw-propellers. The Pennsylvania, launched 1873, cost, according to the statement of her owners, “ready for sea, about 600,000 dollars” (120,000l.); who add that, “if built on the Clyde of as good materials, the saving would have been trifling.” In any attempt, however, to estimate the cost of a steamship I may state, for the information of non-nautical readers, that the outlay on one vessel, even of a similar grade or class, when built for the conveyance of passengers as well as cargo, gives but an imperfect idea of the cost of another vessel, of the same tonnage but not so appropriated. If we take simply the hull, the power of the engines, and the ordinary outfit for a sea-going ship of a particular class, the comparative cost of constructing such a vessel in different countries, or even at different ports in any one country, may be easily ascertained, but, in a passenger-ship so much depends on the quality of the outfit and furnishing, and, especially, on the cabin accommodation, varying as these do almost as much as from a cottage to a palace, I should certainly mislead my readers were I to attempt to supply a comparative cost of passenger-ships built in America and in England.