Now, as compared with wooden ships, the use of iron meant a saving in displacement of about one-third, taking the wooden and the iron ships to be of the same dimensions. From this followed the fact that the iron ship could carry a greater amount of cargo with consequent greater profit to her owners. And, as I have already indicated in another chapter, before it was possible to build ships of great length iron had to be introduced to enable them to endure such longitudinal strains. Again, a wooden ship must have her skin and ribs made of a thickness far greater than an iron ship, for the clear reason that one inch of iron is much stronger than one inch of wood; in other words, to obtain a given strength the iron will take up less room in the ship. Thus in an iron steamer there will be more space available for cargo than in a wooden ship of the same design. We could go on enumerating the advantages of iron, and quote instances of iron ships, whose cargo had got on fire, arriving safely in port and coming into dock where the assistance of the local fire-brigade had enabled the vessel’s own pumps to get the conflagration under. It is only as recently as December of 1909 that the _Celtic_, the well-known White Star liner, during a voyage between New York and Liverpool, had the misfortune to get on fire while at sea. By means of tarpaulins and injections of steam it was possible to control the burning until the Mersey was reached, when it was intended to flood her holds. Had she been a wooden ship instead of steel, or even iron, the _Celtic_ would undoubtedly have ended her days in the Atlantic.