ON THE TIDES. 441 



Condamine, Journal du Voyage a 1'Equateur, 4to, Paris, 1751. Mesure des Trois 

 Premiers Degres, 4to, Paris, 1751. Lacaille, Hist, et Mem. 1751, p. 425, H. 158 ; 

 1755, p. 53. Frisii Disquisitio de Fig. et Mag. Tel. Milan, 1752. Boscovich, De 

 Expeditione, &c. 4to, Romse, 1755. Laplace, Mem. des Sav. Etr. 1773, p. 503 ; 

 Hist, et Mem. 1783, p. 17. Beccaria, Gradus Taurinensis, 4to, Aug. Taur. 1774. 

 Hassencamp, Geschichte, Rinteln. 1774. Gerlach, Gestalt der Erde, Vienna, 1782. 

 Roy, Meas. of a Base at Hounslow Heath, Ph. Tr. 1785, p. 385 ; on the Relative 

 Situations of Greenwich and Paris, 1787, p. 188 ; 1790, p. 11 1. Cassini, &c. on do. 

 4to, Paris, 1790. Herschel on do. Ph. Tr. 1826. Lorgna, Geographia, Verona, 

 1789. Delambre, see Lect. X. Survey by Williams, Mudge, and Dalby, Ph. Tr. 

 1795, p. 414; 1797, p. 432 ; 1800, p. 539 ; 1803, p. 383. Kastner's Mathema- 

 tische Geographic, Gott. 1795. Lambton, Asiatic Researches, vii. 312. Melander- 

 hiem and Svanberg, Zach's Mon. Corresp. i. 372 ; ii. 250, 257 ; vii. 561. Svanberg, 

 Exposition des Operations faites en Lapponie, Stockholm, 1805. Low, Dissertation, 

 Lugd. 1808. Ivory, Ph. Tr. 1809, 1831, p. 109 ; 1834, p. 491. Krayenhoff, Precis 

 des Operations faites en Hollande, 4to, La Haye, 1815. Cagnoli, Method of ascer- 

 taining the Fig. of the Earth by Occupations (trans.), Lond. 1819. Puissant, Traite 

 de Geodesic, 3 vols. 4to, 1819-27. Principes du Fig. du Terrain, &c. 4to. Arago, 

 Recueil d' Observations, 4to, 1821. Carlini, Relazione delle Operation! intrapese in 

 Italia, Milan, 1822. Sabine, Acct. of Experiments with Pendulums, 4to, 1825, and 

 Ph. Tr. 1828-29. Operations Geodesiques executees en Piemont et en Savoie, 

 2 vols. 4to, Milan, 1825-7. Brousseaud, Mem. sur la Mesure d'un Arc du Paral- 

 lele, 1825. Goldingham, Madras Obs. Papers, fol. 1827, Ph. Tr. 1822. Schmidt, 

 Lehrbuch der Mathematischen Geographic, Gott. 1829. Ivory, Ph. Tr. 1809, 1831, 

 p. 109; 1834, p. 491. Francoeur, Geodesic, 1835. 



Figures of the Planets. Maupertuis sur la Figure des Astres, Paris, 1732. La- 

 grange, Hist, et Me"m. de Berlin, 1773, p. 121 ; 1775, p. 273; 1792, p. 258. 

 Laplace, Hist, et Mem. de Paris, 1782, p. 113, H. 43. Legendre, ibid. 1784, 

 p. 370; 1789, p. 372. 



Navigation. See Lect. XXVII. Duillier, Navigation improved, fol. Lond. 

 1728. Maupertuis, Astronomie Nautique, Paris, 1743. Lemonnier, do. 1771. 

 Juan, Examen Maritimo, 2 vols. 4to, Madrid, 1771. Robertson's Navigation, 

 2 vols. Lond. 1786. Moore's, 1796. Lalande, Abrege' de Nav. 4to, 1793. Mac- 

 kay's Nav. 2 vols. 1793. Bowditch's, Lond. 1809. Bouguer, Traite de Nav. 4to, 

 1814. Norie's Nav. Lond. 1822. Kelly's Spherics and Naut. Ast. 1822. Riddle's 

 Nav. 1824. Inman's, Portsea, 1826. 



LECTURE XLVII. 



ON THE TIDES. 



THE form and structure of the solid parts of the globe have afforded but 

 few remarkable features capable of arresting our attention, except the 

 general distribution of land and water, and the permanent differences of 

 elevation of different parts of the earth. But the sea exhibits a series of 

 phenomena far more interesting to the mathematical philosopher, because 

 they admit of a methodical investigation, and of a deduction from general 

 causes, the action of which may be traced in detail. For the height of the 

 surface of the sea at any given place is observed to be liable to periodical 

 variations, which are found to depend on the relative position of the moon, 

 combined in some measure with that of the sun. These variations are 

 * called tides ; they were too obvious to escape the observation even of the 

 ancients, who inhabited countries where they are least conspicuous : for 



