of Ships of the Line, 347 



metacentric formula to any person careful of his reputation as 

 a naval constructor. The fact related by Romme in his VArt 

 de la Marine, proves the possibility of its leading to failure; 

 besideg, accuracy ought never to be sacrificed to an indolence 

 most strongly to be condemned where such an enormous stake 

 ^s the success of a ship of war depends on a little extra exer- 

 tion. Many writers (and even Atwood) have strangely misre- 

 presented and exaggerated Bouguer's estimation of the method 

 he discovered. Clairbois, in particular, by an erroneous dis- 

 cussion of the subject, has contributed to involve the questioa 

 in confusion*. The inventor of the metacentric method him- 

 self unequivocally says, that it requires a modification, in 

 order that it may give correct results at finite angles of heeling; 

 a modification which he points out, and which is as much 

 founded on the true principles of the hydrostatic stability of 

 floating bodies, as the more general method of our countryman. 

 Being aware of these circumstances, and that the displacement 

 must be ascertained for both the methods, and moreover that 

 if the calculator were deprived of a table of cubes, he would 

 not have to boast much either in elegance or facility by pur- 

 suing the metacentric method ; we must condemn such a lax 

 mode of proceeding!. The most objectionable part of At- 

 wood's process consists, we apprehend, in the unavoidable in- 

 correctness, in a practical sense, of his geometrical construction 

 for determining the horizontal moments of the areas immersed 

 and emersed in the vertical sections of a ship, when deflected 

 from the upright position. The following simple method is 

 therefore here subjoined to render more direct this part of the 

 operation, and which although a particular case of a principle 

 of investigation, giving results for any angle of inclination, with 

 trouble increasing as the angle increases, yet is short and 

 simple for angles not exceeding 10", and avoids the errors 

 inevitably attendant on a complex geometrical construction 

 with mathematical instruments. 



tqliet y, •/', and y" be three radial ordinates or half breadths, 

 c^; which 7- corresponds with the upright, and y" with that of 



j^, * Vide " Essai Geom^trique sur 1' Architecture Navale" of this author. 

 ;. f We intend at some future period to enter more fully into this question. 



