FLO 



FLO 



vertical line, the solid will turn on an axis, 

 till it gains a position in which the equili- 

 brium of floating will be permament. 

 From this it is obviously necessary to find 

 what proportion the part immersed bears 

 to the whole, to do which the specific 

 gravity of the floating body must be 

 known ; after which it must be found by 

 geometrical method, in what positions 

 the solid can be placed on the surface of 

 the fluid, so that both centres of gravity 

 may be in the same vertical line, when 

 any given part of the solid is immersed 

 under the surface. These things being 

 determined, something is still wanting, 

 for positions may be assumed in which 

 the circumstances now mentioned con- 

 cur, and yet the solid will assume some 

 other position, wherein it will perma- 

 nently float. However operose and dif- 

 ficult (says an able mechanic) the calcu- 

 lations necessary to determine the stabi- 

 lity of nautical vessels may, in some cases, 

 be, yet they all depend upon the four fol- 

 lowing simple and obvious theorems, ac- 

 companied with other well known stereo- 

 metrical and statical principles. 



Theorem 1. Every floating body dis- 

 places a quantity of the fluid in which it 

 floats, equal to its own weight ; and con- 

 sequently, the specific gravity of the fluid 

 will be to that of the floating body, as 

 the magnitude of the whole is to that of 

 the part immersed. 



Theorem 2. Every floating body is im- 

 pelled downward by its own essential 

 power, acting in the direction of a verti- 

 cal line passing through the centre of 

 gravity of the whole ;' and is impelled 

 upward by the re-action of the fluid 

 which supports it, acting in the direction 

 of a vertical line passing through the cen- 

 tre of gravity of the part immersed; 

 therefore, unless these two lines are co- 

 incident, the floating body thus impelled 

 must revolve round an axis, either in mo- 

 tion or at rest, until the equilibrium is 

 restored. 



Theorem 3. If by any power whatever 

 a vessel be deflected from an upright po- 

 sition, the perpendicular distance be- 

 tween two vertical lines passing through 

 the centres of gravity of the whole, and 

 of the part immersed respectively, will be 

 as the stability of the vessel, and which 

 will be positive, nothing, or negative, ac- 

 cording as the metucentre is above, coin- 

 cident with, or below the centre of gra- 

 vity of the vessel. 



Theorem 4. The common centre of 

 gravity of any system of bodies being 

 given in position, if any one of these bo- 



dies be moved from one part of the sys- 

 tem to another, the corresponding motion 

 of the common centre of gravity, esti~~ 

 mated in any given direction, will be to 

 that of the aforesaid body, estimated in 

 the same direction, as the weight of the 

 body moved is to that of the whole sys- 

 tem. From whence it is evident, that in 

 order to ascertain the stability of any ves- 

 sel, the position of the centres of gravity 

 of the whole, and of that part immersed, 

 must be determined ; with which, and the 

 dimensions of the vessel, the line of floa- 

 tation, and angle of deflection, the stabi- 

 lity or power either to right itself or over- 

 turn, may be found. 



FLOOD, among seamen, is when the 

 tide begins to come up, or the water be- 

 gins to rise, then they call it young flood ; 

 after which it is a quarter flood, half 

 flood, and high flood. See TIDE. 



FLOOD mark, the mark which the sea 

 makes on the shore, at flowing water, and 

 the highest tide : it is also called high- 

 water-mark. 



FLOOR. The lower part of a mine is 

 called the floor, and the upper the roof. 



FLORENTINE -work. When Italy, 

 many years past, enjoyed a state of per- 

 fect tranquillity, and the minds of all 

 ranks of the inhabitants were under the 

 influence of religious enthusiasm, the dif- 

 ferent orders of religious, the priests, and 

 the nobles, each endeavoured to excel 

 the other in the splendid decorations of 

 churches, altars, and shrines ; the arts of 

 the architect, the sculptor, and the paint- 

 er, were exhausted, and the pious almost 

 at a loss how to dispose of their riches in 

 honour of their numerous patron-saints. 

 Mosaic work had been invented many 

 centuries, but some ingenious person, dis- 

 daining the comparative ease of that beau- 

 tiful and expensive manner of imitating 

 paintings, thought of Florentine work, 

 which is performed by inserting frag- 

 ments of precious stones in cement, so as 

 to represent any subject usually treated 

 by the pencil. 



Keysler mentions a Carthusian monas- 

 tery, situated between Milan and Pavia, 

 of uncommon magnificence : " the great- 

 est part of the altars in the church are 

 adorned with elegant representations of 

 birds, flowers, &c. in the Florentine man- 

 ner, performed by the artful position of 

 precious stones inlaid in the marble. The 

 convent entertains two excellent artists, a 

 father and son, to perform these elegant 

 works. The son, Valieri Sac, is so emi- 

 nent in these performances, that the 

 greatest mistress of embroidery would 





