CAM 



CAN 



plant smells of camphor; it abounds in 

 a volatile oily salt, and is warm and sti- 

 mulating. 



CAMUS, (CHAIILES STEPHEK LEWIS) 

 in biography, a celebrated French mathe- 

 matician, was bom at Cressy en Brie, the 

 25th of August, 1699. His early ingenui- 

 ty in mechanics, and his own entreaties, 

 induced his parents to send him to study 

 at a college in Paris, at 10 years of age ; 

 where, in the space of two years, his pro- 

 -, was so great, that he was able to 

 lessons in mathematics, and thus to 

 defray his own expenses at the college, 

 without any farther charge to his friends. 

 By the assistance of the celebrated Va- 

 rirnon, this youth soon ran through the 

 of the higher mathematics, and 

 ac . nred a name amongthe learned. He 

 lumsHf more particularly known to 

 the Academy of Sciences in 1727, by his 

 memoir upon the subject of the prize 

 which they had proposed for that year, 

 viz. " To determine the most advantage- 

 ous way of masting ships ;" in conse- 

 quence of which he was named, that year, 

 Adjoint-Mechanician to the Academy; 

 and in 1730 he wss appointed Professor 

 of Architecture. In less than three years 

 nft rr he was honoured with the secreta- 

 ,-> of the same; and the 18th of A- 

 pYil, 1733, he obtained the degree of As- 

 sociate in the Academy, where he distin- 

 guished himself greatly by his memoirs 

 upon living forces, or bodies in motion 

 acted upon by forces, on the figure of 

 the teeth of wheels and pinions, on pump 

 work, and several other ingenious me- 

 moirs. 



In 1736 he was sent, in company \vith 

 Messrs. Clairaut, Maupertuis, and Mon- 

 nier, upon the celebrated expedition to 

 moannre a degree at the north polar cir- 

 cle; iti ,-V.ich he rendered himself h'gh- 

 ly i'sr- (';!, not only as a mathematician, 

 but. also as a mechanician and an artist, 

 branch 2S for which he hud a remarkable 

 talent. 



In 1741, he invented a gauging rod and 

 sliding rule, by which the contents of all 

 kinds of casks might be immediately as- 

 certained. He was employed in works of 

 importance in his own country, and elect- 

 ed Geometrjcian in the French Acade- 

 my. In 1765 he was chosen a Fellow of 

 the Royal Society of London. On the 4th 

 of -M; 4 y, 1768, he died, in his 69th year, 

 and was succeeded in his office of Geo- 

 metrician to the Academy by D'Alem- 

 bert. His works are numerous, and of 

 great reputation : the principal are, " A 

 Coin-seof Mathematics/' "Elements of 



Mechanics," and " Elements of Arithme- 

 tic." 



CANAL, an aqueduct made for the 

 purposes'of inland navigation. This great 

 improvement in the conveyance of com- 

 modities has arrived at a high degree of 

 perfection, and enables us to transport 

 them even over monntains,where it would 

 appear impossible to preserve a commu- 

 nication, or rather a continuity of water 

 carriage with the subjacent plains. This 

 is effected by the means of locks built of 

 masonry, each of which serves as the con- 

 junction of two different levels. The 

 locks are made only large enou.rrh to ad- 

 mit the vessels employed in the business, 

 and have two gates, one at each end. 

 When a vessel should ascend to a supe- 

 rior level, the upper gate is shut, and the 

 vessel being brought within the lock,the 

 lower gate is also closed, and the upper 

 one opened. By this means the water 

 flows in, and the vessel is raised to the in- 

 tended height. The upper.gate is clos- 

 ed as soon as the vessel has passed, but 

 the water in the lock is preserved for 

 the purpose of letting a vessel down, 

 which is done by shutting the upper 

 gate after she is in the lock, and opening 

 the lower one ; so that she is lowered 

 gradually to the next level. The water 

 in all cases is let in or out by means of a 

 small hatch, making its rise and fall very 

 gradual; else the gates would be torn 

 from their hinges by the rush of so large 

 a body, and the vessel would be endan- 

 gered. We have instances of about twen- 

 ty locks all in half a mile's distance ; but 

 they require very powerful springs to 

 supply a dee quantity of water. Some- 

 times canals are raised above the level of 

 the country ; and we have instances 

 where one canal passes over another. 



The pt-.rt culur operations necessary 

 for making artificial navigations depend 

 upon a number of circumstances. The 

 situation of the ground ; its vicinity or 

 connection with rivers ; the ease or dif- 

 ficulty with wh'.ch a proper quantity of 

 water can be obtained : these, and many 

 other circumstances, necessarily produce 

 great variety in the structure of artificial 

 navigations, and augment or diminish the 

 labour and expense of executing them. 

 When *he ground is naturally level, and 

 unconnected with rivers, the execution 

 is easy, and the navigation is not liable to 

 be disturbed by floods; but when the 

 ground rises and falls, and cannot be re- 

 duced to a level, artificial methods of ra's 

 ing and lowering vessels must be employ- 

 ed, which likewise vary according to cir- 

 canntai 



