HYPSOMETRICAL TABLES. 



These values have been retained in the different formulae proposed later by Gauss 

 in Schumacher's Jahrbuch for 1840, by Schmidt, Mathem. und Physische Geographic 

 II. p. 205, and by Baily, Astronomical Tables, p. 183, which, therefore, only change 

 the form without changing the results. D'Aubuisson, in his formula and tables, Traiti 

 de Geognosie, p. 488, only reduced the barometrical coefficient to its theoretical 

 value, which he determined to be 18365 metres, leaving unchanged the other coeffi 

 cients of Laplace's formula. 



Bessel first introduced, in his formula, Astronomische Nachrichten, No. 356, a sepj 

 arate correction for the effect of moisture. The correction for the temperature oj 

 the air is computed in his tables for two values of the coefficient, that of Gay-Lussaq 

 0.00375, and that of Rudberg, 0.00365. Laplace's barometrical coefficient is rej 

 tained, but the correction for the decrease of gravity is considerably modified. 



In Elie Hitter's formula, in the Memoires de la Societe de Physique de Geneve 

 Tom. XIII. p. 343, the corrections for temperature and moisture are also separated! 

 but other values of the barometrical and thermometrical coefficients, derived fron 

 Regnault's determinations, are used, and a new method is proposed for applying th< 

 correction due to the expansion of air, which is made proportional to the square o 

 the difference between the observed temperatures at each station. 



Baeyer's formula, recently published in Poggendorf's Annalen der Physik unt 

 Chemie, Tom. XCVIII. p. 371, does not belong to either of the two classes just men 

 tioned ; for while it keeps Laplace's barometrical and thermometrical coefficients, i; 

 corrects the effect of temperature by a method analogous to that of Hitter, and it en 

 tirely neglects the effect of aqueous vapor. 



In the following set the tables of Delcros, Guyot, and Loomis develop the formuU 

 of Laplace. The much larger tables of Delcros render unnecessary those of Olt 

 manns, which are yearly reprinted in the Annuaire du Bureau des Longitudes. In 

 stead of Gauss's tables will be found the tables of Dippe, which are computed fron 

 the same formula, but are more extended. Baily's tables close the first series. Tb 

 tables of Plantamour, computed from Bessel's formula, are given here in preference t 

 Bessel's tables, because Plantamour substituted for Laplace's barometrical coefficien 

 that derived from the probably more accurate determination of the relative weigh 

 of the air and mercury by Regnault, viz. 18404.8 metres. E. Ritter's tables, com 

 puted from his own formula, give perhaps, in extreme cases, better results ; bu 

 as, in ordinary circumstances, the altitudes obtained do not much differ from thosi 

 furnished by the less complicated tables of Plantamour, they were not reprintei 

 here. 



The miscellaneous tables which follow furnish useful materials for solving severe 

 questions connected with the barometrical measurements. 



Regnault's table of Barometric Pressures corresponding to Temperatures of th< 

 Boiling Point of Water, revised by Moritz, and its reduction to English measures, wil 

 be found a valuable addition for thermometrical measurements of heights. 



The Appendix to the Hypsometrical Tables now offers, in a new form, a complet* 

 series of tables for the comparison of the different measures of length generally use< 

 for indicating altitudes, the convenience of which will be fully appreciated by thosi 

 who have attempted to collect and to use the abundant contributions furnished by al 

 civilized nations to that branch of geographical science. 



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