BO Questions Jbr Solution relating to Meteorology/, 



According to the first calculation of measurements, the low 

 tide in the Gulf of Mexico would be higher than the low tide of 

 the Atlantic, by about 1™,14 (3 feet, 52). A second calcula- 

 tion gives a similar difference between the two low tides of about 

 0™,85 (2 feet, 63). The mean is 1"^,00 (3 feet, 08). 



But even this slight inequality of level is greater than the real 

 one. In fact, when we compare two seas subject to tides, it is 

 evidently the mean levels, the points, that is to say, equally re- 

 mote from the high and low seas, that ought to serve as data. 

 In this instance, although I can perceive no cause for it, the 

 comparison is made between two low seas. In order to state the 

 matter accurately, therefore, it is necessary to elevate the point 

 of comparison taken in the Gulf of Mexico to half the height 

 of the tide observed in that gulf. The same thing must be done 

 in regard to the eastern or Atlantic side of the Floridas. In the 

 gulf, near the point where the level is terminated, the tide does 

 not rise more than C^jS. On the other side of the Floridas, 

 towards the mouth of the river St Marie, the tide is about 2'",0. 

 The low tide, therefore, is 0™,8 more removed from the mean 

 tide at St Marie than in the gulf. If, then, the mean levels are 

 referred to, as must be done to obtain the real result, instead of 

 l'",0, it will be found that the difference of the level of the two 

 seas is I'^jO less 0™,80 ; that is to say 0"",2 (7i inches.) 



This quantity is evidently within the limits which ought to be 

 assigned to the errors capable of being made in observations 

 embracing the whole breadth of the Floridas. But even though 

 the difference alleged were real, it may be doubted whether any 

 one would be inclined to regard it as a sufficient explanation of 

 the cause of a current which, issuing from the Straits of Bahama, 

 at the rate of no less than five miles an hour (2 leagues), con- 

 tinues its progress into the very middle of the Atlantic, nearly 

 in a straight line, to a distance of 500 leagues, without having its 

 rapidity abated during the whole of that course. 



Let us now consider the Mediterranean. Here the alleged 

 lowness of the level, the presumed cause of the current flowing 

 from the ocean to the Straits of Gibraltar, is said to be the re- 

 sult of an enormous annual evaporation, which the mass of wa- 

 ters contributed by the Nile, Rhone, Po, &c. are insufficient to 

 compensate. Direct and demonstrative proofs of this want of 



