404- 



to ascertain the Correction for Variations of Temperature. 

 within the limits of the natural Temperature of the Climate of tin 

 South of England, of the Invariable Pendulum recently employed by 

 British Observers. By Captain Edward Sabine, of the Royal Artil- 

 lery, Sec. R.S. Read March 25, 1830. [Phil. Trans. 1830,^. 251.] 



The correction for temperature which the author deduces as the 

 general result of his investigation, is 0'44 of a vibration per diem for 

 each degree of Fahrenheit between 30 and 60. He considers this 

 result as entitled to the greater confidence, from the favourable na- 

 ture of the circumstances under which the inquiry was conducted ; 

 since the influence of natural temperature is more permanent and 

 equable than that of temperatures artificially produced. He consi- 

 ders it as desirable, however, that means should be devised of ex- 

 tending experiments on this subject to a wider range of temperatures. 



On a new Register-Pyrometer, for measuring the Expansions of Solids, 

 and determining the higher Degrees of Temperature upon the common 

 thermometric Scale. By J. Frederic Daniell, Esq. F.R.S. Read 

 June 17, 1830. {Phil. Trans. 1830,j9. 257.] 



In the year 1821, the author published in the Journal of the Royal 

 Institution an account of a new pyrometer, and of some determina- 

 tions of high temperatures, in connexion with the scale of the mer- 

 curial thermometer, obtained by its means. The use of the instru- 

 ment then described was, however, limited ; and the author was 

 subsequently led to the invention of a pyrometer of a more universal 

 application, both to scientific researches and to various purposes of 

 art. He introduces the subject by an account of the late attempt of 

 M. Guy ton de Morveau, to employ the expansions of platina for the 

 admeasurement of high temperatures, and for connecting the indi- 

 cations of Wedgwood's pyrometer with the mercurial scale, and veri- 

 fying its regularity. The experiments of that philosopher were by the 

 contraction of porcelain, and by actual comparison with those of the 

 platina pyrometer, at no higher temperature than the melting point 

 of antimony ; but they are sufficient to establish the existence of a 

 great error in Wedgwood's original estimation of his degrees up to 

 that point. This he carries on by calculation, on the hypothesis of 

 uniform progression of expansion, up to the melting point of iron ; 

 the construction of his instrument not admitting of its application to 

 higher temperatures than a red heat, in which platina becomes soft 

 and ductile. Mr. Daniell shows, by an examination ofM. Guyton's 

 results, that he has failed in establishing the point he laboured to 

 prove ; namely, the regularity of the contraction of the clay pieces. 



The pyrometer of the author consists of two distinct parts ; the 

 one designated the register, the other the scale. 



The first is a square tube of black-lead, 8 inches long, cut out of 

 a common crucible of that material, closed at one end, and having at 

 the other a portion of about six tenths of an inch in length cut away 



