JET 



JET 



When an idiot sues, or defends, he 

 shall not appear by guardian, prochein amy, 

 or attorney, but he must be ever in pro- 

 per person : but otherwise of him who be- 

 comes non compos mentis ; lor he shall ap- 

 pear by guardian, if within age, or by at- 

 torney, if of full age. 



JEER, or Jeer-rope, in a ship, is a large 

 rope reeved through double or treble 

 blocks, lashed at the mast head, and on 

 the yard, in order to hoist or lower the 

 yards. 



JEERS, or being brought to the jeers, 

 in the sea language, signifies a person's 

 being punished at the jeer-capstan, by 

 having his arms extended cross-wise, and 

 tied to the capstan bar when thrust 

 through the barrel, and standing thus, 

 with a heavy weight about his neck. In 

 this posture he is obliged to continue, till 

 he is either brought to confess some 

 crime of which he is accused, or has suf- 

 fered the punishment which the captain 

 has sentenced him to undergo. 



JEHOVAH, one of the Scripture names 

 of God, signifying the Being who is self- 

 existent, and gives existence to others. 

 See the article GOD. So great a venera- 

 tion had the Jews for this name, that they 

 left off' the custom of pronouncing it, 

 whereby its true pronunciation was for- 

 gotten. They call it tetragrammaton, or 

 the name with four letters; and believe, 

 that whoever knows the true pronuncia- 

 tion of it cannot fail to be heard by God. 



JEJUNUM, in anatomy, the second of 

 the small intestines, so called, because it 

 is usually found empty. See ANATOMY. 



JESUITS, in church history, or the so- 

 ciety of Jesus, a celebrated religious or- 

 der in the Romish church, founded by Ig- 

 natius Loyola, a Spaniard, who, in the year 

 1738, assembled ten of his companions, at 

 Rome, and proposed to form a new or- 

 der, when it was agreed to add to the 

 three ordinary vows of chastity, poverty, 

 and obedience, a fourth, which was to go 

 wherever the Pope should command, to 

 make converts. They were admitted on 

 their own terms; but the order was 

 abolished, on account of the enormities 

 committed by them, in 1773. 



JET, a black, inflammable, bituminous 

 substance, harder than asphaltum, and 

 susceptible of a good polish ; it becomes 

 electrical by rubbing, attracting light 

 bodies like yellow amber ; it resembles 

 cannel-coal in some particulars, as in 

 hardness, receiving a polish, and not 

 soiling the fingers by the touch. It has 



sometimes been confounded with this 

 substance, but the distinction between 

 them is not difficult : cannel-coal wants 

 the electrical properties of jet, and is 

 much heavier. Magellan supposed that 

 jet was true amber, differing from the 

 yellow kind only in the circumstance 

 of colour, and being lighter, on account 

 of the greater quantity of bituminous 

 matter which enters into its composition. 

 It emits, in combustion, a bituminous 

 smell ; it is never found in strata or con- 

 tinued masses, like fossil-stones, but al- 

 ways in separate unconnected heaps, like 

 true amber. It is found in abundance in 

 the Pyrennean mountains ; also in some 

 parts of Portugal and Spain, in Sweden, 

 Prussia, Germany, Italy, and Ireland. 



JET d'ean, a French term, frequently 

 also used, with us, for a fountain that 

 casts up water to a considerable height 

 in the air. A jet of water is thrown up 

 by the weight of the column of water 

 above its ajutage, or orifice, up to its 

 source or reservoir ; and therefore it 

 would rise to the same height as the 

 head or reservoir, if certain causes did 

 not prevent it from rising quite so high. 

 For, first, the velocity of the lower parti- 

 cles of the jet being greater than that of 

 the upper, the lower water strikes that 

 which is next above it ; and as the fluids 

 press every way, by its impulse it widens, 

 and consequently shortens the column. 

 Secondly, the water at the top of the jet 

 does not immediately fall off, but forms a 

 kind of ball or head, the weight of which 

 depresses the jet ; but if the jet be a little 

 inclined, or not quite upright, it will play 

 higher, though it will not be quite so 

 beautiful. Thirdly, the friction against 

 the sides of the pipe and hole of the adju- 

 tage will prevent the jet from rising quite 

 so high, and a small one will be more im- 

 peded than a large one. And the fourth 

 cause is the resistance of the air, which 

 is proportional to the square of the velo- 

 city of the water nearly ; and therefore 

 the defect in the height will be nearly in 

 the same proportion, which is also the 

 same as the proportion of the heights of 

 the reservoirs above the ajutage. Hence, 

 and from experience, it is found that a 

 jet properly constructed, will rise to dif- 

 ferent heights, according to the height of 

 the reservoir, as in the following table of 

 the heights of reservoirs and the heights 

 of their corresponding jets ; the former 

 in feet, and the latter in feet and tenths 

 of a foot. 



