Transatlantic steamships

In April 1838 two British paddle steamers raced to New York. The Sirius, a small Irish Sea ferry chartered by the British and American Steam Navigation Company, left Cork on April 4 and arrived on April 22. The Great Western, a purpose-built 236-foot wooden steamship designed by Isambard Kingdom Brunel for the Great Western Steamship Company, left Bristol on April 8 and arrived the next day, April 23, after a crossing of about fifteen days. A sailing packet usually needed four to six weeks westbound, against the prevailing winds, so the steamers cut the trip drastically and kept to a timetable.¹²

Steam had driven river boats since Fulton's Clermont (1807) and James Watt's engine, and the paddle steamer Savannah had crossed the Atlantic in 1819 using steam for a small part of the voyage. Skeptics, led by the scientist Dionysius Lardner, argued that no ship could carry enough coal for the whole distance. Brunel's insight was that a ship's carrying capacity grows with its volume, while resistance grows more slowly, so a bigger ship can carry the fuel it needs. The Sirius almost ran out of coal and burned spare spars and cabin fittings to arrive, a reminder of how close the argument was.¹²

Steam shipping soon improved. Brunel's Great Britain (1843) was the first large iron ship driven by a screw propeller, which was more efficient than paddle wheels. In 1840 Samuel Cunard began a regular mail service from Liverpool to Halifax and Boston under a British government contract, and iron hulls, screw propellers and compound engines cut crossing times to about a week by the 1880s. Steamships carried the mail, goods and the tens of millions of emigrants who left Europe in the nineteenth century, and they were the beginning of the end of commercial sail.