We must now see how this all came about. It depended really on two things: first, the use of iron, and subsequently steel, for the building of bigger hulls; and secondly, the invention of the screw propeller to take the place of the old-fashioned paddle-wheel. Briefly how this came to pass is as follows. As far back as 1821 a Mr. Aaron Manby had built an iron craft 120 feet long and 18 feet wide, and she steamed from London to Paris, being employed for the next twenty years on the Seine. She was thus the first iron ship to put to sea, and was called the _Aaron Manby_, after her builder. Then in 1832 Laird & Co. of Birkenhead built the 148-ton paddler _Lady Lansdowne_ for the trade between England and Ireland. But it was not until 1843 that the first really large iron ship, the famous _Great Britain_, was built, intended as an improvement on the _Great Western_. But before we speak of the _Great Britain_ we must see something of the way the propeller came in, for the two subjects are intimately connected. At its best the paddle-wheel, except for excursion steamers and certain kinds of tugs, is a very clumsy means of driving a ship through the water. It is the most obvious, because historically it is analogous to the action of the duck, of the first primitive man who paddled his small craft, or of the later Egyptians who rowed with oars down the Nile. But for open sea work the paddle-wheel is an awkward encumbrance, and apart from tugs and pleasure steamers it was last seen, in European waters at least, in the mail steamers running from England to Flushing and Ostend comparatively recently. [Illustration: [_By courtesy Messrs. T. H. Parker._ THE “ROBERT F. STOCKTON.” (Captain Ericsson, 1839.)] [Illustration: [_By courtesy Messrs. T. H. Parker._ AN EARLY CROSS-CHANNEL STEAMER. This picture of 1855 shows the English and French Royal Mail Steam Packets “Queen” and “Empress.”]