We wish to call the reader’s attention now to the _Servia_, of which an interesting picture is reproduced opposite page 154. In her was embodied the result of another scientific discovery which has revolutionised the construction of the deep-sea ship, whether propelled by steam or sails. As iron had superseded wood, so now steel was to take the place of iron as the material of which to build the hull. So thoroughly, indeed, has this practice spread that during the year 1909, with the exception of a few small wooden vessels whose aggregate tonnage does not much exceed a thousand, the entire amount of new British shipping in that year was constructed of steel, and iron was not used at all for the hull. Such a fact is highly significant of the value of the newer material. Although as far back as 1873 the French had used this in constructing parts of their warships, it was not until four years later that the British mercantile marine began to be interested in it. But at length the Cunard Company were convinced of its superior virtues over iron, and ordered the _Servia_ to be built of this material. When she made her appearance in 1881, she was the largest and most powerful ship, excepting the _Great Eastern_, that had ever been launched; her measurements were 515 feet, breadth 52 feet, depth 37 feet, with 7,392 gross tonnage. She lowered the Atlantic voyage once more to seven days, one hour, thirty-eight minutes, her speed being 17 knots, though it was not until 1884 that she really showed her full abilities. We may sum up the advantages which were now recognised in mild steel as consisting of, firstly, a saving of 25 per cent. in weight, just as we saw that iron exercised a similar superiority over wood. “Mild” steel is very ductile and can easily be fashioned into the required shape suitable for a steamship without risk of cracking. Iron is comparatively brittle, and steel is more uniform in quality. The latter will also endure a greater strain on its elasticity, and this had already been appreciated by the Royal Navy years before commercial shipbuilders realised its full value. Although the first cost of a steel-built ship was greater than one constructed of iron, yet that extra cost was found to be over-balanced by other considerations. Just as iron was stronger than wood, so steel was proved to be stronger than iron: consequently, the weight of the ship was diminished, which meant that the ship could carry a greater amount of fuel or cargo, or allowed of her being fitted with more powerful, though more weighty, engines. Steel is now very much cheaper than wrought iron, and is used not merely for the plates of the hull, but in almost every portion of the ship’s construction. Even in sailing ships the yards, masts, and rigging are to a large extent now made of this material. [Illustration: THE “UMBRIA” (1884). _From a Painting. By permission of the Cunard Steamship Co._] [Illustration: THE “ORIENT” (1879).