i<54 , Letter refpeEl'tng Sound and Light, 



" An inftance of thU has lately occurred to a young gentleman In Edinburgli, a marr 

 who certainly promifes in the courfe of time to add confiderably to our knowledge of the 

 laws of nature. The tra£lory — was firft defcribed by Huygens : Bomie and Perks have 

 ihewn, that it is the involute of the catenaria. — The curve which the author calls a cycloid 

 is the companion of a trochoid, and is only a diftortion of the figure by which Newton had 

 very fimply and elegantly folved the fame problem. — On the whole it appears, that this in- 

 genious gentleman has been fomewhat unfortunate in the choice of thofe problems, which 

 he has felefted as fpecimens of the elegance of the modern mode of demonftration." Effay 

 on cycloidal curves, Britifh magazine for April 1800. Is this an admonition ? Or is there 

 here any remark which can at all apply to my infenfibility to Dr. Smith's merit in harmonics ? 



I have read Dr. Smith's work with attention, and I imagine, from the polite manner in 

 which Profeffor Robifon is pleafed to fpeak of my eflay, he will not hefitate to allow that 

 I have underftood it. I took it up with great expectations ; thefe expeiSations having been 

 completely difappointed, I thought it right to ftate my cool and unprejudiced opinion of its 

 merits, in order to prevent a fimilar difappointment in others. It is impofllble therefore 

 that an " attention" to any " admonitions" of a general nature, wherever they may be 

 found, can influence fuch an opinion ; and fo far only as I am fuppofed to be an incom- 

 petent judge on the fubje£l of harmonics, can it be aflerted that it was either blameable or 

 fuperfluous for me to exprefs that opinion. As a mathematician and an optician I value 

 Dr. Smith highly, but I muft ftill beg leave to affirm, that his whole book of harmonics 

 contains far, far lefs information, than either of the articles Temperament and Trumpet 

 in the fupplement of the Encyclopaedia. 



r do not mean to be underftood that this work Is fo contemptible, as not to contain ths 

 leaft particle of important matter ; but it appears to me that its errors counterbalance its 

 merits. The only improvement on which Profeflbr Robifon himfelf feems to fet a high 

 value, is the application of the phsenomena of beats to tuning an inftrument : on the other, 

 hand, I conceive that the miftatement relative to the non-interference of different founds, 

 IS an inaccuracy which, far outweighs the merit of Dr.. Smith's fliare of that improvement. 

 I have aflerted,. that " Dr. Smith has written a large and obfcure volume, which for every 

 " purpofe but for the ufe of an impradticable inftrument, leaves the whole fubjeil of tem- 

 *' perament precifely where it found It," and that *' the fyftem propofed for his changeable 

 •' harpfichord is neither in that nor in any other form capable of pra£lical application." 

 FrofeiTor Robifon. on the contrary fays, "" we do not fee how it can be difputed, that Dr. 

 " Smith's theory of the beating of imperfeft confonances, is one of the raoft Important 

 *' difcoveries both for the praftice and the fcience of mufic, that have been offered to the 

 " public. We are inclined to confider it as the moft important that has been made fince. 

 " the days of Galileo. We are obliged to call it his difcovery. Merfennus indeed had 

 " taken particular notice of this undulation of imperfed confonances, and had offered con- 

 " je£tures as to their caufes ; conje£lures not unworthy of his great ingenuity. Mr. Sauveur 

 "_alfo takes a ftill more particular notice of this phenomenon, and makes a moft ingenious 



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