COASTING CARGO STEAMER (1855).
From the Model in the Victoria and Albert Museum.
In the same year that the Pacific took the water was launched the Himalaya, of which a beautiful little model is [here illustrated]. She was built for the P. and O. Line. This fine ship-rigged steamship was constructed of iron at Blackwall in 1853, and in the following year was bought by the British Government and steamed away from Plymouth with soldiers for the Crimea. She was of 4,690 tons displacement, and in that year made a record run from Gibraltar at an average speed of 13½ knots. Originally she had been built for carrying both cargo and passengers, but now she is, or was, ending her sphere of usefulness as a coal hulk at Devonport. Her coal “endurance”—she could carry 1,200 tons—made her a valuable asset, and her six water-tight bulkheads rendered her still more efficient. As will be seen from the illustration, she had a single propeller, and this was driven by yet another type of engine, which we have now to consider. We refer to the vertical trunk engine. We shall be able to understand this better if we examine [the illustration facing page 132], which reproduces a drawing of a similar type of engines installed in the P. and O. Candia, built a year later than the Himalaya. In the trunk engine the piston-rod was done away with, so that the connecting rod is attached directly to the piston within a trunk or tube. This trunk passes through a steam-tight stuffing-box in the cylinder cover, and is made wide enough to allow of the lateral vibrations of the connecting rod inside. As long as steam pressures did not exceed 35 lb. this proved to be satisfactory; but the friction of the stuffing-boxes when they became of large dimensions was a serious drawback. The Candia, for which these engines were made, was a screw ship, and the cylinders were placed in a fore-and-aft position. By means of this type of engine, employing trunks, the height required was greatly lessened, and it was not necessary, as will have been noticed was essential in the case of the Great Britain’s engines, that part of them should come up through the deck. Thus, the trunk type meant a saving of valuable space. Between the cylinders were arranged the condensers, which were of the jet type. We may stop to remind the reader that the condenser had been the invention of Watt, who had improved on the Newcomen engine not merely by covering over the top of the cylinder, but by condensing the exhausted steam in a separate vessel, called a condenser. This condensation he brought about by means of a jet of cold water, and the same principle was still employed in the Candia. Condensation having taken place, the water thus formed, together with any air which has got in, is then drawn off by the air-pumps, which will be seen in the illustration to be worked from an intermediate crank. It will be remarked on glancing at [the left of the picture] that the Candia’s crank shaft was connected with the propeller shaft by means of spur gearing, which doubled the speed of the screw, and so of the ship, but yet allowed the actual engines to run comparatively slowly. This toothed wheel idea was a better method than that employed in the Great Britain’s engines, though it was only just one stage better. There was a rooted objection in the early days of the screw to running the engines at a great speed, and thus it was only by some such means of gearing that the propeller was made to revolve quickly. In the course of time, when a wider experience and knowledge of engineering matters had been obtained, the gearing was done away with and the engines became direct-acting, and so there ensued far less friction, an absence of complication, and less expense caused by gearing. At the same time the power obtained by the newer method became more direct.
A customary apparatus nowadays adopted for steamships is the surface condenser, and in the effort to increase the steam pressures this has been a potent factor. But it had already been tried by Watt, by David Napier, and re-introduced by Samuel Hall in 1831. The surface condenser consists of a number of brass tubes about three quarters of an inch in diameter, through which a stream of cold water circulates. This necessarily keeps the pipes cool, and thus condenses the exhaust steam which is thrown on to them from the cylinder; it is practically a kind of tubular boiler. Instead of the jet, as in the older form of condenser, it is the outside of the pipes which performs the office, and the air-pump does its work as before. The condensed steam is now available for feeding the boiler, and after being filtered the feed pump draws it into a heater and thence it is led into the boiler once more. If the reader will now turn to [the illustration facing page 132] once more, he will see in the right hand of the picture that in the Candia the feed and bilge pumps were worked by small beams from an eccentric.
By being able to use this water for the boilers a great economy was effected, but in some of the P. and O. liners the boilers suffered rather badly, since an injurious chemical action was set up owing to the continuous return of the same water backwards and forwards from the condenser. Nowadays the problems connected with the condenser have been fully mastered, and the advantage of being able to use distilled water is obvious; for one of the surest and quickest methods of bringing about ruin is to use sea-water for the boiler, over which it will lay a thick crust of salt.
[The third illustration facing page 134] is interesting as representative of a type of coasting steamer introduced about the year 1855. She shows very well the simplest form of an iron ship propelled with a screw, and evinces sufficient resemblance to the dying sailing ship before the steamer had taken on a distinctive character of her own. In a word, here is the steamship not in her crudity, as in the case of the Clermont, but certainly in her elementary form without any of those extra decks and houses which were still to come, and which to-day give such distinct personality to the steamship. It will be seen that she is just a flush-decked vessel, with a central protection amidships for her engines and boilers. There is no forecastle, no poop, and in the development of type she stands at the beginning. She was built for the North Sea trade, and in bad weather must have been a singularly wet boat. She was only of 677 tons gross register, and the absence of any shelter would, when steaming to windward in a bad sea, cause her to be swept from end to end. Similarly, her stern being equally unprotected by either poop or quarter deck, she would be at the mercy of a bad following sea. It was not surprising that this elementary type soon gave way to those modifications that we shall see hereafter. In design of her body this present model illustrates again Scott Russell’s system of obtaining a capacious ship combined with the qualities of slipping through the water with the minimum of resistance. This will be especially noticeable by regarding the long straight middle body. She was propelled by oscillating engines, and a two-bladed screw, having also sails on her three masts.
And so we come to that famous monstrosity and wonder of her decade the Great Eastern, some idea of whose appearance will be obtainable from a model of her, [illustrated herewith]. Here again will be found a repetition of a curious rig with the half-dozen masts, of which the second and third carried yards and square-sails, and the others the usual fore-and-aft sails set on the gaffs here seen. Although she carried one triangular headsail, yet this was a staysail, and it is significant that in this notable ship we find the disappearance of the bowsprit, a change that is so characteristic of the modern liner. Much more than either the Great Western or the Great Britain this epoch-making monster stands for something altogether distinctive in the evolution of the steamship. Frankly, in spite of her virtues, she was a creature born out of due time. Historically, she exhibits in no uncertain manner the extraordinary and almost incredible speed at which the development of the steamship had progressed in fifty years, during which period designers, ship-builders, and engineers had to feel their way in the most cautious manner. No ship was built with such a length as hers until the White Star Oceanic in 1899; no vessel ever had such a beam until the coming of the Mauretania and Lusitania, and even they only exceed the Great Eastern’s extreme width by a mere five feet. But it is half a century since the latter was built, when all the experience that we possess now was not yet obtained.
THE “GREAT EASTERN” (1858).
From the Model in the Victoria and Albert Museum.