32 Naval Architecture and 



riers put in practice, in 1772, similar principles. The cele- 

 brated Chapman also applied it. 



We conceive that the subject cannot be decided a priori ; 

 but must be referred to general principles in ships. Hence, 

 Dupin remarks, its superiority must be determined by show- 

 ing that the efficient ship of war, on Sir Robert's adapta- 

 tion of this principle, is constructed with less timber and 

 fastening than on the old plan ; that it has the weight placed 

 lower ; that it is of less expense, or has improved qualities. 

 Now, we cannot avoid remarking, that this has never been 

 shown, but only asserted ; and that there is a great defi- 

 ciency of calculated data on these points. Dupin himself 

 only hazards an opinion on the subject ; but, as a mathema- 

 tician, he ought not to have been satisfied with anything less 

 than an accurate statement. He passes over the new plan of 

 attaching the beams to the side, as of little consequence, 

 without showing it to be attended with less weight than the 

 old methods ; whereas they must be estimated in the com- 

 parative weights of the ships. It is evident, from mere in- 

 spection, that the new mode is the heaviest, and that it con- 

 tributes, in too material a degree, to raise the centre of 

 gravity of the ship, and diminish its stability. To deter- 

 mine the efficacy of the diagonal riders to prevent arching, 

 Dupin ought to have shown that they are equal, for this 

 purpose, to the internal coat of planking, so boldly dis- 

 pensed with by Sir Robert, independent of the massy inte- 

 rior ranges of timber, between which the beam-ends are 

 confined; for it is evident, that these strong longitudinal 

 binders would of themselves effect the same object in a very 

 material degree. The shelf- pieces, which were used by 

 former English surveyors, are not of English introduction, 

 nor of French solely ; as, by reference to ships constructed 

 in the Archipelago and the Levant, they will be found to 

 have been used for ages. 



We think it but justice to observe, that when some new 

 mode of fastening the beam-ends was required from the 

 scarcity of warden-knees, that Mr. Roberts proposed a plan 

 which was found to succeed so well as to obtain for him a 

 parliamentary grant of 800/. Whether Mr. Roberts derived 

 it from Du Hamel we are unable to decide — there is a simi- 

 larity in the plans; but the objection urged against the 

 plan by Mr. Knovvles, of the beams of free growth being 

 split by the bolts in the beam-arm, is certainly futile; as it 

 was easily remedied by placing them out of the same line 

 of fibre. 



