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I. XIV. Observations o?i Dr. Thomson's Ciiliqve on Mr. Sep° 

 riNGs's new Meiliod of Sh'tp-buildivg. i»^ Alexander. 

 Stuart, Esq. 



To Mr. Tllloch. 



Sir, — 1 OBSERVE in Dr. Thomson's Annals for last month, 

 among the analyses of books, an account of Mr. Scppings's me- 

 thod of constructing sl'.ips. As that gentleman has thought fit 

 to erect him'>elf into the situation of critic as ^\ ell as analyst of 

 the books described in his journal, it would ])e but rendering the 

 public that justice to which thev are entitled, if he would make 

 himself acijuainted with the sciences concerning which he has 

 the a<;surance to speak, — if indeed he has dither the capacity and 

 acquirements of a pliilosopher, or the honesty of an editor. His 

 account of Mr. Seppings's construction is such a mixture of 

 ignorance and blundering as would disgrace a common boat- 

 builder : but it is of a piece with the confusion of his conceptions 

 on the Trigonometrical Survey, on mathematical subjects in ge- 

 tieral, and on gcologv, a science in which his total and ridiculous 

 ignorance is only etjuallcd by his ill-breeding and insolent dog- 

 matism. In the review novv luider notice he talks of " sulisti- 

 tuting triangidar or oblique beams for the parallel ribs which 

 have hitherto constituted a ship's frame." 



To pass over the total want of correspondence between the 

 terms here made etjuivalent, triangvlar and olliq^ie ; who could 

 comprehend from such a description, that Dr. Thomson's " tri- 

 angular or oblique beam" was a connected frame-work added 

 to the ordinary rectangular framing of a ship, and so connected 

 •with it as to form diagonal ties or supports, similar in their ef- 

 fects to those w^hich constitute the very existence of common 

 carpentry? — a branch of mechanics of which this self-erected 

 judge has probablv never heard, or he could not have so de- 

 plorably blundered in the account he has attempted to give of 

 this improvement. But to proceed: He talks of " substituting 

 the oblique for the parallel ribs, which adds prodJiiiously to 

 the stiffness as well as the strength." Really, a ship built of 

 oblique triangular beams seems very well fitted for the voyage of 

 such a critic to the land of Gotham, since to his other acquire- 

 ments he probably has not added that of witc!icraft — the power 

 of keeping himself afloat in a sieve. If Dr. Thomson's conceit 

 and insolence would permit his ignorance to derive any benefit 

 from our friendlj advice, we v/ould tell him that Mr. Seppings's 

 very ingenious improvement consisted in substituting a series of 

 diagonal trusses in lieu of those ])arallel to the framing called 

 riders, and that the ship's ceiling was omitted as superfluous ; 



while 



