310 COSMOS. 



Disturbances of equilibrium and consequent movements of 

 the waters are partly irregular and transitory, dependent upon 

 winds, and producing waves which sometimes at a distance 

 from the shore and during a storm rise to a height of more 

 than 35 feet; partly regular and periodic, occasioned by the 

 position and attraction of the sun and moon, as the ebb and 

 flow of the tides ; and partly permanent, although less intense, 

 occurring as oceanic currents. The phenomena of tides which 

 prevail in all seas (with the exception of the smaller ones that 

 are completely closed in, and where the ebbing and flowing 

 waves are scarcely or not at all perceptible) have been perfectly 

 explained by the Newtonian doctrine, and thus brought 

 tk within the domain of necessary facts." Each of these 

 periodically recurring oscillations of the waters of the sea 

 has a duration of somewhat more than half a day. Al- 

 though in the open sea they scarcely attain an elevation of 

 a few feet, they often rise considerably higher where the 

 waves are opposed by the configuration of the shores, as for 

 instance, at St. Malo and in Nova Scotia, where they reach 

 the respective elevations of 50 feet, and of 65 to 70 feet. " It 



named. From the geodesical levellings which, at my request, my friend 

 General Bolivar caused to be taken by Lloyd and Falmarc, in the years 

 1828 and 1829, it wa% ascertained that the level of the Pacific is at the 

 utmost 34 feet higher than that of the Caribbean sea; and even that 

 at different hours of the day each of the seas is in turn the higher, 

 according to their respective hours of flood and ebb. If we reflect, that 

 in a distance of 64 miles, comprising 933 stations of observation, an 

 error of three feet would be very apt to occur, we may say that in these 

 new operations we have further confirmation of the equilibrium of the 

 waters which communicate round Cape Horn (Arago, in the Annuaire 

 du Bureau dps Longitudes pour 1831, p. 319). I had inferred, 

 from barometrical observations instituted in 1799 and 1804, that 

 if there were any difference between the level of the Pacific and the 

 Atlantic (Caribbean Sea), it could not exceed three metres (nine 

 feet three inches) ; see my RelaL hist., t. iii. pp. 555-557, and 

 Annales de Cliimie. t. i. pp. 55-64. The measurements, which appear 

 to establish an excess of height for the waters of the Gulf of Mexico, 

 and for those of the northern part of the Adriatic Sea, obtained by com- 

 bining the trigonometrical operations of Delcrois and Choppin with those 

 of the Swiss and Austrian engineers, are open to many doubts. Notwith- 

 standing the form of the Adriatic, it is improbable that the level of its 

 waters in its northern portion should be 28 feet higher than that of the 

 Mediterranean at Marseilles, and 25 feet higher than the level of th< 

 Atlantic Ocean. See my Asie centrah, t. ii. p. 332. 



