256 



Level of the atlanic and pacific oceans. 



I have obtained from the philosophical transactions of 

 the Royal Society, the following particulars resulting 

 from Mr. Lloyd's survey of the Isthmus of Panama. 



The rise and fall of the tide at Chagres,at the close of the 

 dry season is 1 . 1 6 foot, and no difference was observed during 

 the rainy season. High water mark being always the same. 



High water mark at Chagres and Panama are at the 

 same time, viz : 3h. 20m. at full and change. High water 

 mark at Panama is 13.85 above that of Chagres. Half 

 the rise and fall of spring tides is at Panama 10.61 feet, 

 and at Chagres 0.58 of a foot ; assuming half the rise 

 and fall above the low water of spring tides, to be the 

 respective mean levels ; the mean height of the Pacific at 

 Panama, is 3.52 feet above that of the Atlantic at Chagres. 



At high water, the Pacific is raised at mean tides 10.61 

 feet, and the Atlantic 0.58 of a foot, above their respective 

 mean levels ; the Pacific is, therefore, highest at such times 

 by (10.61— 0.58+352zz) 13.55 feet. At low water, both 

 seas are the same quantities below the respective mean 

 levels ; and therefore, at such times, the Pacific is lower 

 than the Atlantic by (10.61— -0.58— 3.52zi) 6.51 feet. 



In every twelve hours, therefore, and commencing with 

 high tides, the level of the Pacific is first several feet 

 higher than that of the Atlantic ; it becomes then of the 

 same height, and at low tide is several feet lower : again, 

 as the tide rises the two seas are of the same height, and 

 finally at high tide the Pacific is again the same number of 

 feet above the Atlantic as at first." 



It is to be observed, that the bay of Panama, from its pecu- 

 liar form and position, gives occasion to a greater flow and cor- 

 responding ebb of the tide, than take place on the shores of the 

 Pacific, which are open to sea, as Chagres is to the Atlantic, 



