race of speed was commenced, and, with it, the tradition of the Blue Riband. With Great Western, Isambard Kingdom Brunel laid the foundations for new shipbuilding techniques. He realised that the carrying capacity of a ship increases as the cube of its dimensions, whilst the water resistance only increases as the square of its dimensions. This means that large ships are more fuel-efficient, something very important for long voyages across the Atlantic. Constructing large ships was therefore more profitable. Moreover, migration to the Americas increased enormously. These movements of population were a financial windfall for the shipping companies, some of the largest of which were founded during this time. Examples are the P&O of the United Kingdom in 1822 and the Compagnie Générale Transatlantique of France in 1855. The steam engine also allowed ships to provide regular service without the use of sail. This aspect particularly appealed to the postal companies, which leased the services of ships to serve clients separated by the ocean. In 1839, Samuel Cunard founded the Cunard Line and became the first to dedicate the activity of his shipping company to the transport of mails, thus ensuring regular services on a given schedule. The company's vessels operated the routes between the United Kingdom and the United States. Over time, the paddle wheel, impractical on the high seas, was abandoned in favour of the propeller. In 1840, Cunard Line's began its first regular passenger and cargo service by a steamship, sailing from Liverpool to Boston, Massachusetts. As the size of ship increased, the wooden hull became fragile. Beginning with the use of an iron hull in 1845, and then steel hulls, solved this problem. The first ship to be both iron-hulled and equipped with a screw propeller was , a creation of Brunel. Her career was disastrous and short. She was run aground and stranded at Dundrum Bay in 1846. In 1884, she was retired to the Falkland Islands where she was used as a warehouse, quarantine ship, and coal hulk until she was scuttled in 1937. The American company Collins Line took a different approach. It equipped its ships with cold rooms, heating systems, and various other innovations but the operation was expensive. The sinking of two of its ships was a major blow to the company which was dissolved in 1858. In 1858, Brunel built his third and last giant, . The ship was, for