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passed over in this line was G33*32 feet above the level of high water 

 at Panama. Their constitutions were now beginning to suffer from 

 the continued exposure to rain, and they therefore determined, after 

 building a secure station on the banks of the Chagres, to defer all 

 future operations till the ensuing year, when the dry season should 

 be established. On the 7th of February, 1829, they resumed their 

 labours, carrying on their levels from a point of the river below their 

 former station, and 152*55 feet above high-water mark at Panama, 

 along the course of the river to a place distant about 12 miles from 

 its mouth, called La Bruja, where the water in dry seasons is very 

 brackish, and from which there is no perceptible current to the sea. 



The result of this survey fixes the mean height of the Pacific, at 

 Panama, at 3*52 feet above the Atlantic at Chagres. Between the 

 extremes of elevation and depression of the greatest tides in the Pa- 

 cific at Panama, there is a difference of 27*44 feet; but the mean 

 difference at the usual spring tides is 21*22. At Chagres, this dif- 

 ference is only 1*16 foot, and is the same at all seasons of the year. 

 Hence it follows, that at high water, the time of which is nearly the 

 same on both sides of the Isthmus, the Pacific is raised, at mean tides, 

 10*61 feet, and the Atlantic 0*58 foot, above their respective mean 

 levels, giving to the former an elevation above the latter of 13*55 

 feet. At low water, both seas being below their respective mean 

 levels, by the same quantities as before stated, the Pacific will be 

 lower than the Atlantic by 6*51 feet; so that thus, in the course of 

 every interval from one high tide to the succeeding one, the level of 

 the Pacific is at first higher, then equal, and afterwards lower than 

 the Atlantic ; and then again passing back by the same steps it re- 

 gains its former elevation as the tide returns. 



The great chain of mountains which extends from the Andes in 

 South America to the Mexican and Rocky Mountains in North Ame- 

 rica, is not, as is generally supposed, absolutely continuous through 

 the Isthmus connecting these two continents ; for the northern Cor- 

 dillera on the eastern side of the province of Veragua, breaks into 

 detached mountains of considerable height, having steep and rugged 

 sides. To these succeed numerous conical mountains, rising from 

 plains and savannahs, and seldom exceeding from 300 to 500 feet in 

 height. Between Chagres on the Atlantic side, and Chorrera on the 

 Pacific, the conical mountains are less numerous, and are separated 

 by extensive plains, with only a few occasional insulated hills of in- 

 ferior extent and elevation. Thus it happens that at the narrowest 

 part of the Isthmus, a break occurs in the mountain- chain, which, 

 in almost every ether part, is uninterrupted from its northern to its 

 southern extremities ; a circumstance which marks this spot as pe- 

 culiarly adapted for the establishment of a communication across. 

 The author has laid down on his map two lines for a rail-road, both 

 commencing at a point near the junction of the river Trinidad with 

 the Chagres, and crossing the intervening plain, the one to Chorrera, 

 the other to Panama. The latter line, although the longer of the 

 two, would have the advantage of terminating in a considerable city. 



