AND ITS DELTA. 183 



It has already been said that the tides on the coast rise about 

 three feet perpendicular, but they are not lunar tides; another 

 cause must be sought: the bay of Mexico being a species of 

 Mediterranean sea, surrounded by the continent and a close 

 chain of islands, is not sensibly susceptible of the gravitating pow- 

 er of the sun and moon ; the tides take place only once in 

 twenty four hours, and nearly at the same hours in the morning; 

 they depend altogether upon the winds, which, during the re- 

 gular summer season, blow in upon the land all day; and in 

 the night, it is either calm, or there is a small returning land 

 breeze: the sea breeze commences in the morning about nine 

 or ten o'clock, and ceases in the evening about sun set; the wa- 

 ters having acquired a momentum from the action of the wind 

 continue to rise until about day break, when it is high water; 

 a tide depending upon such a cause must be subject to frequent 

 anomalies: in the winter, as may be expected from this theory, 

 the tides are extremely irregular, being governed by the va- 

 riable winds of that uncertain season. 



This small tide produces an effect upon the Mississippi; 1 

 have noted at New-Orleans (during the absence of the inun- 

 dation) arise of fourteen inches, about sun rise; and at Man- 

 shac from 6 to 8 inches; this ascent of the waters of the Mis- 

 sissippi is produced merely by a swell or wave; the current at 

 the same time continually issuing from the channel into the 

 ocean; this tide requires a considerable time to make its pro- 

 gress upwards against the current: 'those who have perused 

 Condamine's account of his voyage down the Maragnon are 

 acquainted with every thing that can be said upon this curi- 

 ous subject. The great Newton has observed, that the tides 

 which take place nearly at the same time at London-bridge, 

 and at the mouth of the Thames, are not the same; but that 

 at the bridge is the same which happened twelve hours befote 

 at the Nore. 



It is probable that any tide coming up to New-Orleans is the 

 same which arrived three days before at the mouth of the river, 

 consequently the distance from New-Orleans to the mouth of 

 the river is divided by the tides into three parts; (i. c.)'one 

 tide at each extremity, and two others making their progress 



