Great Britain, in addition to, or perhaps because of, her growing power as a centre of manufacture and shipping, thrust out her long arms to India and China, to Australia and New Zealand. The growth of the population at home and the opportunities for colonists in America, in Australia, and other parts of the world, resulted, almost for the first time, in the construction of ships intended solely for the purpose of carrying passengers and mails. A large travelling public was, for the first time in history, beginning to appear. In the ’forties, therefore, began a division of ships into two major classes—carriers of freight and carriers of passengers. Sailing ships were still greatly more numerous than steamships and, as a matter of fact, the finer sailing ships were still considered the aristocrats of the sea. But as steam engines were perfected, and particularly after the screw propeller was invented by Colonel John Stevens, an American, early in the 19th Century, and perfected by F. P. Smith, an Englishman, and John Ericson, the Scandinavian-American, steamships increased in power, in speed, in reliability, and consequently in popularity. This period saw the beginning of a number of new steamship lines, some of which, notably the Cunard and the Royal Mail, are still in existence, although they are now operated on a scale that could never have been imagined even by their forward-looking founders. And now, as if for the purpose of aiding this great increase in the efficiency and size of steamships, came another development, without which the leviathans of to-day would be impossible, and but for which the beautiful clipper ships which were brought so close to perfection in the middle of the 19th Century might still be supreme upon the seas, or at least might still be able to hold their own against their steam-driven sisters. It was the rolling mill, a thing prosaic enough to-day, that made possible the great increase in the size and strength of ships. The rolling mill and the screw propeller are still the basic improvements that have led to the building of most of the ships on the high seas to-day. The first suggestion of the use of iron plates for the building of ships was received with withering sarcasm. How could ships be built of iron when everyone knows that iron will sink? But even in the face of such criticism ships were built, and they were not only built—they were launched and they floated. [Illustration: THE _GREAT EASTERN_ _A ship that was built half a century too early. This huge vessel, built in 1857, was designed to make the voyage from England to Australia without refuelling. She never made the voyage to Australia, but was used to lay the Atlantic cable. She was ahead of her time, for engines had not developed to the point where she could be properly propelled._ ]