The Britannic.

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There had been this slow and gradual advance in ocean steam pressures, with a consequent reduction in coal expenditure, when in 1856 came a movement in the direction of economy by the introduction of the compound engine, by Messrs. Randolph Elder & Co. (later John Elder & Co.), which was soon to develop into a revolution in marine steam enginery. The Pacific Steam Navigation Company has the credit of first accepting this change in applying it to their ships, the Valparaiso and Inca. The original pressure used was 25 pounds to the inch: the cylinders were 50 and 90 inches in diameter, and the piston speed from 230 to 250 feet per minute. The idea of using steam expansively by this means was of course not new, as it dates back to Hornblower (1781), but with the low pressures which had been used at sea there was no reason for its adoption afloat. Difficulties were experienced by the Pacific company with their earlier engines, but the line adhered to their change, and for nearly fourteen years were almost alone in their practice.

These changes made the use of a cylindrical boiler necessary, as the form best able to withstand the increased pressure. The old box-like shape has disappeared; and if the shade of Oliver Evans is ever able to visit us, it must be with an intense feeling of satisfaction to find his ideas of eighty years since now accepted by all the world.

The date 1870 marks the advent of a new type of ship, in those of the Oceanic Company, better known as the White Star line, built of iron by Harland & Wolff, of Belfast—engined with compound engines, and of extreme length as compared with their breadth. They established a new form, style, and interior arrangement, which has largely been followed by other lines, though the extreme disproportion of length and beam is now disappearing. The Britannic and Germanic, the two largest of the earlier of this line, are 468 feet in length and 45 feet 3 inches in beam, carrying 220 cabin passengers and 1,100 in the steerage, besides 150 crew. They develop 5,000 indicated horse-power, and make their passage, with remarkable regularity, in about 8 days 10 hours to Queenstown. The earlier ships of this line, when first built, had a means of dropping their propeller-shaft so as to immerse more deeply the screw; so many inconveniences, however, were associated with this that it was given up. Their general arrangement was a most marked advance upon that of their predecessors—an excellent move was placing the saloon forward instead of in the stern, a change almost universally followed.

In the same year with the Britannic came out the City of Berlin, of the Inman line, for some years the largest steamer afloat (after the Great Eastern), being 520 feet in length by 44 feet beam, of 5,000 indicated power, and in every way a magnificent ship.

The Bothnia and Scythia were also built in 1874, by the Cunard company, as representatives of the new type, but were smaller than the ships of the same period built by the Inman and White Star lines. They were of 6,080 tons displacement and 2,780 indicated horse-power, with a speed of 13 knots. The pressure carried was 60 pounds. These ships had by far the largest cargo-carrying capacity (3,000 tons measurement) and passenger accommodation (340 first-cabin) of any yet built by the company. With the addition of this great number of steamers, change was not to be expected for some years; and it was not until 1879, when the Guion company put afloat the Arizona, that a beginning was made of the tremendous rivalry which has resulted in putting upon the seas, not only the wonderful ships which are now running upon the Atlantic, but in extending greatly the size and speed of those employed in other service.

Several things had combined in the latter part of this decade to bring about this advance. The great change between 1860 and 1872, from the causes already noted, which had reduced coal consumption by one-half, was followed by the introduction of corrugated flues and steel as a material for both boilers and hull. With this came still higher pressures, which were carried from 60 to 80 and 90 pounds. In August, 1881, a very interesting paper was read by Mr. F. C. Marshall, of Newcastle, before the Institution of Mechanical Engineers, in which he showed that a saving of 13.37 per cent. in fuel had been arrived at since 1872. The general type of engine and boiler had remained the same in these nine years, but the increased saving had been due chiefly to increased pressures. It is curious that at the reading of both the paper by Sir Frederick Bramwell, in 1872, and that of Mr. Marshall, in 1881, there should have been pretty generally expressed a feeling that something like a finality had been reached. So little was this opinion true that, though over thirteen per cent. saving had been effected between these two dates, a percentage of gain more than double this was to be recorded between the latter date and 1886. In these matters it is dangerous to prophesy; it is safer to believe all things possible. Certainly the wildest dreamer of 1872 did not look forward to crossing the Atlantic at 20 knots as a not unusual speed.