168 COSMOS. 



terrestrial spheroid. The excess at the equator in conse- 

 quence of the curvature of the upper surface of the globe, 

 amounts, consequently, in the direction of gravitation, to 

 somewhat more than 4-f- times the height of Mont Blanc, or 

 only 2 1 times the probable height of the summit of the 

 Dhawalagiri, in the Himalaya chain. The lunar inequalities 

 (perturbation in the moon's latitude and longitude) give, 

 according to the last investigations of Laplace, almost the 

 same result for the ellipticity as the measurements of degrees 

 viz., T ^. The results yielded by the oscillation of the 

 pendulum give on the whole a much greater amount of com- 

 pression viz., 



* The oscillations of the pendulum give ^' g . 7 , as the general result of 

 Sabine's great expedition (1822 and 1823, from the equator to 80 north 

 latitude) ; according to Freycinct, ^. 3 , exclusive of the experiments in- 

 stituted at the Isle of France, Guam, and Mowi (Mawi) ; according to 

 Forster, ^. s ; according to Duperrey, ^^ ; and according to Liitke 

 (Partie N antique, 1836, p. 232), 5 ^ calculated from eleven stations. 

 On the other hand, Mathieu (Connaiss. des Temps, 1816, p. 330) fixed 

 the amount at ^ ?, from observations made between Formentera and 

 Dunkirk ; and Biot, at n ^, from observations between Formentera and 

 the Island of Unst. Compare Baily, Report on Pendulum Experiments, 

 in the Memoirs of the Royal Astronomical Society, vol. vii. p. 96 ; also Bo- 

 renius, in the Bulletin de VAcad.de St. Petersbourg, 1843, t. i. p. 25. The 

 first proposal to apply the length of the pendulum as a standard of measure 

 and to establish the third part of the seconds pendulum (then supposed 

 to be everywhere of equal length) as a pes horarius, or general measure, 

 that might be recovered at any age and by all nations, is to be found in 

 Huygens' Horologium Oscillatorium, 1673, Prop. 25. A similar wish 

 was afterwards publicly expressed, in 1742, on a monument erected at 

 the equator by Bouguer, La Condamine, and Godin. On the beautiful 

 marble tablet which exists, as yet uninjured, in the old Jesuits' College 

 at Quito, I have myself read the inscription, Penduli simplicis cequi- 

 noctialis unius minuti secundi arclietypus, mensurce naturalis exemplar, 

 utinam universalis! From an observation made by La Condamine, in 

 his Journal du Voyage a VEquateur, 1751, p. 163, regarding parts of 

 the inscription that were not filled up, and a slight difference between 

 Bouguer and himself respecting the numbers, I was led to expect that 

 I should find considerable discrepancies between the marble tablet and 

 the inscription as it had been described in Pans ; but after a careful 

 comparison, I merely found two perfectly unimportant differences: 

 " ex arcu graduum 3|/' instead of " ex arcu graduum plusquam 

 -rium," and the date of 1745, instead of 1742. The latter circumstance 

 Is singular, because La Condamine returned to Europe in November, 

 1744, Bouguer in June of the same year, and Godin had left South 



