NOTES. xliii 



3272077-14 T.; the s<>mi-minor axis, 3261139'33 T. ; the ellipticity, 

 _^. T7 , ? ; and the length of a mean degree of the meridian, 57013*109 T. with 

 a probable error of 2'8403 T. ; whence the length of a German geographical 

 mile, 15 to a degree, is 3807'23 T. [In British measures, the semi-major 

 axis is 20924774 feet; the semi-minor axis, 20854821 feet; the length of a 

 mean degree of the meridian, 364596'0 feet, with a probable error of 18'16 

 feet ; and that of a geographical mile, 60 to a degree, G086'76 feet. ED.] Pre- 

 vious combinations of measurements of degrees varied between --3 and ^ T : 

 thus Walbeck (De Forma et Magnitudine Telluris in Demensis Arcubus Meri- 

 diani definiendis), in 1819, gives -g^rg; Ed. Schmidt, (Lehrbuch der math, 

 tmd phys. Geographic, S. 5), in 1829, gives ^r ** from seven measures. 

 Respecting the difference of the compression deduced from measurements in 

 different longitudes, see Bibliotheque universelle, T. xxxiii. p. 181, and 

 T. xxxv. p. 56 ; also Connaissance des Terns, 1829, p. 290. From the luiiar 

 inequalities, Laplace found, by the older tables of Burg, s^V? (Expos, du 

 Syst. du Monde, p. 229), and subsequently, by employing the observations 

 of the moon discussed by Burckhardt and Bouvard, ^VT (Mecan. celeste, 

 T. v. pp. 13 and 43.) 



( 131 ) p. 157. The values of the compression deduced by means of the 

 pendulum are as follows : The general result of Sabine's great expedition. 

 (1822 and 1823, from the equator to 80 N. lat.), ^%. T ; Freycinet, exclud- 

 ing the experiments at the Isle of France, Guam, and Mowi, 5-5^.5 ; Foster, 

 EF5-7?; Duperrey, ^g. 7 ; Liitke (Partie nautique, 1836, p. 232), from 11 

 stations, ^^ . Lesser ellipticities have been given by the pendulum observa- 

 tions between Formentera and Dunkirk, g^s-i? according to Mathieu (Con- 

 naissance des Terns, 1816, p. 330) ; and by those between Formentera and 

 Unst, 3-71* according to Biot. Baily, Report on Pendulum Experiments, in 

 the Memoirs of the Royal Astr. Society, Vol. vii. p. 96 ; also Borenius, in 

 the Bulletin de 1'Acad. de St.-Petersbourg, 1843, T. i. p. 25. The first 

 proposal to adopt the length of the pendulum as a standard of measure, and 

 to establish the third part of the seconds pendulum (supposed to be every 

 where of equal length) as a pes honor arius, the measure of a unity which 

 might be recovered at any future age of the earth, and by nations dwelling on 

 any part of its surface, is found in Huygens' Horologium oscillatorium, 1673, 

 Prop. 25. In 1742, the same wish was publicly enounced in an inscription 

 on a monument erected at the equator by Bouguer, La Coudamine, and Godin. 

 On a handsome marble tablet, which I have seen uninjured in the old Jesuits' 

 College at Quito, it is said : " Penduli simplicis eequinoctialia uniua minuti 

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