Before the advent of the steamship, sailing vessels were developed to a high degree of efficiency. The speedy clippers of 1816 to 1845 used to cross the Atlantic at an average speed of 6 to 9 miles per hour and sometimes even better, which compares favorably with a common steam freighter of to-day. The largest sailing vessel ever built was the _Thomas W. Lawson_, a seven-masted schooner. She was launched in 1902, but foundered in 1907 off the Scilly Islands. This great ship was a steel vessel 395 feet long, with a displacement of 10,000 tons and a cargo capacity of 7,500 tons. She had a sail spread of 40,617 feet. FROM OARS TO PROPELLERS Although a century has elapsed since the first steam-driven vessel made its way across the Atlantic Ocean, sails have been as yet by no means swept off the face of the sea. Nevertheless, even when sailing vessels had no competitors they did not furnish a perfectly satisfactory means of transportation. The fickleness of wind power was felt in this application as well as in that of windmills, and inventors racked their brains for some more certain means of propelling ships. Naturally, when the steam engine was a proven success, efforts were made to apply this newly discovered power to ships. How to make steam drive a ship was a problem. At first it was proposed to use a system of oars which would be moved back and forth in imitation of oarsmen and John Fitch’s first steamboat in 1786 was driven by a set of paddles operated in a manner similar to that of paddling a canoe. It was a very natural evolution from oars to paddle wheel, which consists of a series of oars mounted in a wheel so that they will come into play one after the other. The propeller, although not invented by Col. John Stevens (as has been popularly supposed), was first applied by him to steam navigation when he constructed a small steamboat on the Hudson River in 1804. But the simplicity of the paddle wheel and its high efficiency, particularly in quiet harbors and shallow inland waters, gave it preference over the propeller. In rough seas, however, the paddle wheel was far from ideal. It was too easily broken by heavy waves and between 1855 and 1865 the propeller displaced it completely for ocean-going vessels. WATER JET PROPULSION