JETSAM 



3147 



JEVONS 



JET 'SAM. See FLOTSAM, JETSAM AND LIGAN. 



JETTE, zhetay', SIR Louis AM ABLE (1836- 

 ), a Canadian jurist and statesman, one 

 time lieutenant-governor of Quebec, later chief 

 justice of the superior court of that province, 

 and in 1903 a member of the Alaska Boundary 

 Commission (see ALASKA, subtitle History}, 

 which settled the dispute between the United 

 States and the Dominion. Jette was born at 

 L'Assomption, Que., was educated at L'As- 

 somption College, and was called to the bar 

 in 1857. As a young man he was a frequent 

 contributor to political and legal periodicals, 

 and was also active in politics. He sat in the 

 Dominion House of Commons as a Liberal from 

 1872 to 1878, but refused the position of Min- 

 ister of Justice offered him in the latter year 

 by Alexander Mackenzie. From 1878 to 1898 

 he was puisne judge of. the superior court of 

 Quebec, from 1898 to 1908 lieutenant-governor 

 of Quebec, and in 1908 again returned to the 

 superior court, of which he became chief justice 

 in 1909. He resigned from the bench in 1911. 

 Jette was for many years professor of civil 

 law, and later became dean of the law faculty, 

 at Laval University. He was created Knight 

 Commander of the Order of Saint Michael 

 and Saint George in 1901. G.H.L. 



JETTY, jet' i, a wall or pier, made of timber 

 and stone, or of stone alone, built into a river 

 or harbor to deepen the channel or for use as 

 a breakwater. Sometimes jetties are built 

 along the sides of streams to prevent further 

 washing away of the banks. Many open har- 

 bors have great walls or banks built into the 

 sea for added protection, such as the jetties 

 of the harbors of Dunkirk and Calais in France, 

 and in Galveston, Texas. The Columbia River 

 on the Pacific coast of the United States has 

 the longest jetty in the world, nearly four and 

 one-half miles in length. Before it was built, 

 the harbor was feared by all sailors, because 

 of the shifting bars; now there is a single 

 channel of the uniform depth of twenty-nine 

 feet. 



The Mississippi Jetties were built to keep 

 the mouths of the Mississippi from filling up 

 with the silt and fine sand that the water 

 brings down in vast quantities. The river emp- 

 ties into the Gulf of Mexico through four 

 principal mouths, known as passes. They are 

 called Southeast Pass, South Pass, Grand Pass 

 and Southwest Pass. In 1874 these mouths 

 were so choked up with bars that large steam- 

 ers could not get through. Captain James B. 

 Eads (which see) suggested building two long 



jetties like two walls, along the banks and out 

 into the Gulf. These would keep the water 

 from encroaching on the land and would force 

 it through a narrower channel so much more 

 swiftly that the current would scour out the 

 bars and keep the channel clear and of a uni- 

 form depth. 



In 1875 the jetties were built. Rows of piles 

 1,000 feet apart were driven into the bottom 

 to mark the position of the walls, then timber 

 mattresses, made of willow logs fastened with 

 planks, were sunk by piling stones upon them. 



MISSISSIPPI JETTIES 



The bottom layer of mattresses was fifty feet 

 wide, but each layer was made narrower till 

 the top one measured only twenty feet across. 

 These dikes of timber and stone filled up with 

 silt and sank deeper and deeper into the river 

 bottom till they became immovable. Inside 

 of two years a channel thirty feet deep had 

 been made that has been maintained ever since. 

 In 1906 similar jetties were built in the South- 

 west Pass, and both sets have been repaired 

 and improved several times. 



JEVONS, jev'onz, WILLIAM STANLEY (1835- 

 1882), an English philosopher and economist, 

 born at Liverpool, who was the first to simplify 

 logic for the benefit of beginners. His principal 

 works in this field are Elementary Lessons in 

 Logic; The Principles of Science, and Studies 

 in Deductive Logic. His works on political 

 economy include The Coal Question; Theory 

 oj Political Economy ; The Value of Gold and 

 Money and The Mechanism of Exchange. He 

 held a position in the royal mint of Australia; 

 was professor of logic, and mental and moral 

 philosophy, and Cobden lecturer on political 



