BAR 



BAR 



sotli year, he removed to Rome, and puifued his (ludies vrlth 

 fuch afiiduity and fiiccefs, that he became one of the moil 

 graceful painters of his time. At Rome he was particularly 

 encouraged by the proteftion of cardinal della Rovere, and 

 by the commendation of Michael Angelo. On his return 

 to Urbino he g;ained great applaufe by feveral piftures, and 

 more efpecially by that of a St. Margaret, which induced 

 pope Pius IV. to invite him to Rome, and to employ him, 

 in conjiinftion vi'ith Federigo Zucchero, in the decorations 

 of his palace of Belvedere. It has been faid, that his fupe- 

 rior merit excited the jealoufy of his brother arlii^s to fuch 

 a degree, that they gave him poifon at an entertainment. 

 Whether this be true or not, his health rlejlincd ; and for 

 the recovery of it, he was under a necefTicy of recurring to 

 his native air, and of intermitting his labours. However, 

 by due attention, his life was prolonged to the advanced age 

 of 84 years. His genius principally inclined him to the 

 painting of rehgious fubjefts ; and his works evince that it 

 was his chief ambition to imitate Correggio in his colouring, 

 and Raphael in his manner of dcfigning. It is eafy to ob-' 

 ferve, that he endeavoured to refemble the former illuftrious 

 artill in the fweetnefs of his tints, in the harmony of his 

 colouring, in the gracefid airs of the heads, in the difpo- 

 fition of his draperies, and the forms of his Bambinos, 

 though he fometimes exprefled the mufcular parts of the 

 human body too ftrongly. He feldom painted any hifto- 

 rical figure without having either modelled it in wax, or 

 placed fome of his difciples in fuch attitudes as he wifhed to 

 reprefent; his fifter was the model for the Madonnas, and 

 her child for his Bambinos. He is faid to have employed 

 feven years in painting at Affife, the birth-place of St. Fran- 

 cis, a pifture called the " Pardon," in which the figure of 

 the faint kneeling, by the force of (hade, feems to rife from 

 the canvas. The works of this mafter are numerous; the 

 principal of which are at Rome, in the Belvedere, and feveral 

 churches; at Urbino, Afllfe, Cortona, Arezzo, and other 

 towns in Italy; in the gallery of Florence; the Efcurial; 

 and the duke of Orleans's colle£lion. Baroccio engraved 

 four of his own pieces with peculiar fpirit, and more than 

 thirty more have been publifhed by different engravers. 

 Pilkington and Strutt. 



BA ROCHE, La, in Geography, a town of France, in 

 the department of the Orne, and chief place of a canton in 

 the diltrift of Domfront ; 4 miles S. S. E. of Domfront. 



BAROCO„in Lofu; denotes the fourth mode of the 

 fecond figure of fyllogifms. 



A fyllogifm in baroco has the firft propofitioii univerfal 

 and affirmative, but the fecond and third particular and 

 negative; and the middle term, the attribute or predicate 

 in the two firft. — For example: 



" BA Every virtue is attended with difcretion : 

 RO Some kinds of zeal are not attended with 



difcretion : 

 CO Therefore feme kinds of zeal arc not %-iitues." 

 "BAR Nullus homo non eft bipes: 

 OC Non omne animal eft bipes: 

 O Non omne animal eft homo." 

 BAROLITE, in Mineralogy. See Withemte. 

 BAROMETER, compounded of ^cl-oc, "weight, and 

 fxiTfov, meafure, an inftrument for meafuring the weight of 

 the atmofphere and its variations, in order chiefly to deter- 

 mine the changesof weather, and the heightsof mountains, &c. 

 The barometer is frequently confounded with the barofcope, 

 though fomewhat improperly ; the latter, in ftridlnefs, be- 

 ing an inftrument that barely fhews an alteration in the 

 weight of the atmofphere : but it is one thing to know that 

 the air is heavier at one time than another, and another to 

 Vol. III. 



meafure how much that difference is; which is the bufmefs 

 of the barometer. 



The barometer is founded on the Toiricellian experiment, 

 as it is called from its inventor Torricelli, who, in con- 

 fequence of the previous fuggeftion of Galileo, with regard 

 to the afcent of water in a pump, upon drawing up the 

 pifton, proceeded, in 1643, *° ^^ \<\x!a mercur)' a glafs tube, 

 hermetically fealed or clofe at one end, the other end being 

 open and immerfed in a bafon of ftagnant mercury. Judg- 

 ing that, in the former cafe, the water was fuftained in the 

 pump by the prefFure of the air on the water in the veflel, in 

 which its open end was immerfed, and that it was the mea- 

 fure of this preffurc, he hence concluded that mercury would 

 in like manner be fupportcd by it in the tube, and at a 

 height which was alfo the meafure of the air's preffure, or 

 about 13 times lefs than water. His experiment was com- 

 pletely verified ; for he obferved that the mercury defcended 

 in the tube, and finally fettled at the perpendicular height 

 of 295 Roman inches, whether the tube was vertical or in- 

 clined, according to the known laws of hydroftatical preffure. 

 This famous experiment was repeated and divnlified in va- 

 rious forms, with tubes filled with otlier fluids, fuch as 

 ivater, wine, oil, &c.; and the refult being the fame, the 

 weight and preffure of the air were eftablithed beyond con- 

 tradiftion or doubt. Thofe who had any remaining doubts 

 were completely fatisfitd by a beautiful experiment exhibited 

 by M. Auzout. He provided a fmall box or pliial 

 EFGH (P/atelX. Pneumatics, Jig. •]^.) into which he in- 

 felted two glafs tubes, AB, CD, each three feet long, 

 in fuch a manner that they were firmly fixed at one 

 end, and reached nearly to the other end. The tube AB 

 was open at both ends, and CD was clofed at D. This 

 apparatus being completely filled with mercury, by unfcrew- 

 ing che tube AB, and filling the box and the tube CD, and 

 then fcrewing in the tube AB and alfo filhng it, was in- 

 verted, whilft a finger was held on the orifice A, and fet up- 

 right in the manner exhibited in Fig. 75, immerfing the 

 orifice A of Fig. 74, or a of Fig. 75, in a fmall veffel 

 of quickfilver. Upon this, the mercury ran out at the ori- 

 fice a, till its furface mn within the phial defcended to the 

 top of the tube La. The mercury began alfo to dcfcend in 

 the tube dc {Fig. 75.) coirefponding to DC in Fig. 74, and 

 flowing over into the tube ba, efcaped at a, till that in Jc 

 was very nearly on a level with mn. In ba, the mercury 

 ftood at i, 295 inches above the furface op of the mercury 

 in the ciftern, as in the Torricellian tube. Indeed, this 

 whole apparatus may be firft confidered as a Torricclhan 

 tube of an uncommon form, from which the mercury would 

 flow out at a. But when any of it efcaped, a vacant fpace 

 would be left above mn, and the mercury in the tube de 

 would alfo defcend, and running over into ba, fupply its 

 wafte, till dc became almoft empty, and could no longer 

 fupply ba. The inner furface being therefore depreffed as 

 much as pofllble, till it became level with b, no more mer- 

 cur)' could enter into b, and yet its column being too heavy 

 to be fupported by the preffure of the air on the mercury in 

 the ciftern op, it muft defcend in ba, till it finally fettled at 

 the height Ic, equal to that of the mercury in the Tonicel. 

 lian tube. In this ftate if a fmall hole g were made in the 

 upper cover of the box, the external air would rutli in by its 

 weight, and prefs on the mercury in the box. This preffure 

 would immediately caufe the mercury to rife in the tube dc 

 to /, 29'- inches above mn. It likewife preffes on the mer- 

 cury at k in the tube ba, balancing the preffure of the air on 

 the mercury in the ciftern. The mercury in the tube, 

 therefore, muft defcend to the bottom by its own weight. 

 By this experiment the doftrine of the gravity and preffure 

 4P of 



