B O U 



creafe of refraaion, when the ftar can be obfcrvcd below 

 the line of the level ; on the laws of the JHrerent dciifities 

 of the «ir at different heights ; on the tffed of the attrac- 

 tion of the mountains upon a plummet ; on the method of 

 ellimatiii?, the encrsof naviijators in compining their courfe 

 and dirtance ; on the new conllrndion of a log foi meafni-- 

 in-T the ftip's way i and on a vaiiely of other paniciibrs ; 

 whicli, with thole already recited, will be duly noticed 

 in the courfe of ihi^ work. Of iiis heliomcter for determni- 

 iuc the diameters of the larger planrti in a tclefcope with 

 two objea glaffcs, his expcrimei.ts on the reciprociition of 

 the pcnduhini, and iiis method of meafuring the force of 

 light, S:c. Stc, we fliall introduce an account in Uioir pvo- 

 jier places. 



The principal works of M. Couguer, that have been le- 

 parately pubhihed, are "The figure of the earth, deter- 

 mined by the obfervations in South America," 1749, ^to. ; 

 «' Treatife on navigation and pilot.ige," Paris, tjjz, 4to., 

 abridged by La Caillc in one volume, 8vo. 1768. " Trea- 

 tife on (liips, their condruclion and motions," i7.)6. 410. ; 

 and " Optical treatifc on the gradation of liglit," lirft pub- 

 lifhed in 17 29, and afterwards in 1760, 4to. The follow- 

 ing detail of his chief communications to the royal academy, 

 and of the volumes of the " Memoires," in wliich they may 

 be found, will probably gratify the cnriofity,and dircft the le- 

 fearches of our mathematical and philofopliical readers. Ac- 

 cordiuTly, we have in the " Mcm.oires" for 1726, a com 



parifoiTof the force of the folar and lun^r light, with that papers 

 of candles; for 1731, obfervations on the curvilinear mo- '■■ ' 



lion of bodies in mediums; for 17; 2, upon the new curves 

 called the " lines of purfuit;" for 1733, to determine the fpe- 

 cies of conoid, to be conllruaed upon a given bafe, which 

 is e.^cpofed to the (liock of a "fluid, fo that the impulfe 

 may be the leaft poffible ; and a determination of the orbit 

 of comets; for 1734, comparifon of the t\yo laws which 

 the earth and other planets mull obferve in the figure, 

 which gravity caufes them to take ; on the curve lines pro- 

 per to form the arches in domes; for 173J, obfervations on 

 the equinox ; on the length of the pendulum; for 173'!, 

 on the lengtli of the pendulum in the torrid zone ; on the 

 manner of determining the figure of the earth, by the mea- 

 fures of the degrees of latitude and longitude; for 1739, 

 on the agronomical refraftions in the torrid zone ; obferva- 

 tions on the lunar eclipfe of September Sth 1737, made at 

 Quito; for 1744, lioit account of the voyage to Peru by 

 the members of the royal academy of fcicnccs, to meafure 

 the degrees of the meridian near the equator, and from 

 thence, to determine the figure of the earth, a communica- 

 tion no lefs elegantly, than accurately vviitten ; for 1745, 

 experiments made at Q;iito, and divers other places in ti.e 

 tonid zone, on the expanfion and contraition of metals by 

 heat and cold; on the problem of the mailing of (hips; 

 for 174'', treatifc on fliips, their ftrudlure and motions, 

 (lee Mf.tacentre and Ship); on the impulfe of fluids 

 upon the fore parts of pyramidoids, having their bafe a tra- 

 pezium ; continuation ot the fliort account, given in 1744, 

 of the voyage to Peru for meafuring the earth ; for 1747, 

 on a new conftrudion of the log and other iullruments for 

 meafuring the run of a (hip ; for 174S, of the diameters of 

 the larger planets ; the new inftrument called a heliometer, 

 proper for determining them, with obfervations of the fun ; 

 obfervation of the eclipfe of the moon, Aug. Sth, 1748 ; 

 for 1749, fecond memoir on aftronomical refraftions, ob- 

 ferved in the torrid zone, with remarks on the manner of 

 conftrufting the tables of them ; figure of tlie earth, deter- 

 mined by Meifrs. Eoug-.ier and Coudamine, with an abridg- 



B O U 



ment of the expedition to Peru ; for j 7,50, obfervatl«n9 of 

 the lunar echple, Dec. 13th, 17.50; for 17^1, on the form 

 of bodies, moll proper to turn about themfelvts, when they are 

 puflied by one of tlieir extremities, or any other point; on the 

 moon's parallax, with theeftimatiou of the changes, caufed 

 in the parallaxes by the figure of the earth ; obferva- 

 tion of the lunar eclipfe, Dec. zd, 1751 ; for 1752, on the 

 operations made by fcamen, called " Corredtions ;" for 

 1753, obftrvations'on the paffage of mercury over the fun, 

 May 6th, 17 1.3 ; on the dilatations of the air in the atmo- 

 fphcre ; new "treatifc of navigation, cor.taining the tlieory 

 and practice of pilotage, or working of fliips ; for 1754, ope- 

 rations, &:c. for didinguifliiiig, among the different dcternii- 

 nations of the degree of the meridian near Paris, that which 

 ought to be preferred ; on the direction which the ftring of 

 a plummet takes; folution of the chief problems in the work- 

 ing of (liips ; for i 755, on the apparent magnitude of ob- 

 jrdls ; fecond memoir on the ch.ief problems in the working 

 of (hips ; for 1757, account of the treatife on the working 

 of Ihips ; on the means of meafuring the light. In the vo- 

 lumes of the prizes, given by the academy, are the fol- 

 lowing pieces by Bouguer ; in vol. i. on the mailing of 

 fliips ; in vol. ii. on the method of exactly obferviiig at fea, 

 the height of the liars, and the variation of the compafs ; 

 alio on the caufe of the inclination of the planets' orbits. 

 M. Bouguer was alio for 3 years a writer in the Journal 

 des S^avans, to which he communicated feveral uletul 



In his earlier years, M. Bouguer had lived in a ftate of 

 fechifion from general intercourfe with the world, and he 

 had thus acquired a caft of temper, which marked his cha- 

 i-aftcr in more advanced life. Although he was univerfally 

 ackuovvledged to polTcfs fuperior talents, and to be dilcin- 

 guilhcd by an afliduity and zeal, no lefs fuccefsful than in- 

 defatigable, in various departments of ufeful fciencc ; he 

 iifdulgcd a dep^ree of fufpicion and jealoufy, with regard to 

 his reputation, whic'i dilgulled fonie of thofc with whom 

 he was under a neceflity of aflociating, and which difquieted 

 his own m.ind. Fully fenfible of the importance and utility 

 of his own performances, he was apt to confider others, 

 who were engaged in fimilar puriuits, as competitors with 

 himfelf, and to grudge them the reputation which they 

 julUy acquired, from an apprehcniion that his own credit 

 would be thus dimir.ifttd. Hence arofe his difputes with 

 La Coudamine, one of the companions of his' voyage, and 

 an'oci:ite in his labours in America ; and the mortification 

 he experienced from the public fuffrage that feemed to have 

 been bellowed on that academician. It is much to be la- 

 me:ited, that mean jealoulies of this kind fhould fulfill 

 among perfor.s, diftinguilhed by their literature and fcience; 

 beeaule they arc not only difreputable to themfelves, but 

 injurious to the advancement of ufeful knowledge. M. 

 Bouguer, after a courfe of inceffant apphcation, which un- 

 dermined his health, clofed his life on the 15th of Augull, 

 175S, at the age of 60 years. Mem. of the French Aca- 

 demy, 1758. Nouv. Did. Hill. Montucla, " Hiil. des 

 Mathematiques," by De La Lande, torn. iv. Gen. Biog. 

 BOUHIER, John, a pecfon of eminent literary charac- 

 ter, was born at Dijon, in 1673, and firll educated at a Je- 

 fuit feminary, where his extraordinary talents for languages 

 were carefully cultivated. The peculiar fl;udies of his pro- 

 feffion were profecuted at Paris and Orleans, wlience he 

 returned to Dijon, and began the exercife of it in 1673. 

 Here he diilinguiflied himfelf by his profeffional praflice, 

 and was admitted into the parliament, fucceeding his father 

 in the office of prefident a mortier. As he devoted hi.s 



leifure 



