On the Comparative Level of Lakes and Seas. 331 



almost at the same time, In the month of April 1837, the existence of an 

 enormous hollow.* The two English travellers estimated the depression 

 of the Dead Sea at — 93 toises. M. le Comte de Bertou has the merit 

 of having first determined the amount of the depression by barometrical 

 measurements. M. Caillier,t after discussing a portion of the measure- 

 ments, concluded it amounted to — 208 toises ( — 406 metres). More 

 recently,! M. de Bertou, by combining, in his memoir, all the observa- 

 tions made in March 1838, and in May 1839, estimated it at — 215 

 toises ( — 419 metres). M. Schubert calculated the level of the Sea of 

 Tiberias at — 89 toises ( — 535 feet), but he did not measure the Dead 

 Sea. M. Russegger, whose journies in Africa and Asia have enriched 

 geology with many important observations, has watched the indications 

 of the barometer in November and December 1838, during 15 days at 

 Jaffa, at Jerusalem, and at the Dead Sea. He thinks it possible, owitig 

 to the want of corresponding observations, that the result of his measure- 

 ments may leave a mean doubt of 200 feet at most ; but, allowing for 

 this doubt, he calculates that higher than the level of the Mediterranean, § 

 Jerusalem stands -f- 2479 feet (413 toises), and Bethlehem + 2538 feet 

 (423 toises) ; and belo%v the level of the Mediterranean, the Lake Tibe- 

 rias is — 625 feet ( — 104 toises), and the Dead Sea — 1341 feet 

 ( — 223 toises, or — 435 metres). In proportion as, in the geodsesical la- 

 bours, from the variations of successive results, the level ofthe Caspianhas 

 ascended from — 50 to — 13 toises in relation to the Mediterranean, the 

 level of the Dead Sea has proportionally descended. After the numerous 

 doubts which have prevailed regarding the great depression of this last 

 level, a trigonometrical survey, executed in the autumn of 1841 by Lieu- 

 tenant Symond of the British Royal Navy, has given the result, that 

 the surface of the waters of the Dead Sea is 251 toises (489 metres) 

 lower than the highest house of Jaffa, and probably 219 toises (427 metres) 

 lower than the surface of the Mediterranean. This trigonometrical re- 

 sult differs accidentally only 8 metres from the result of the barome- 

 trical measures of MM. Bertou and Russegger. The geological pro- 

 blem of the depression of the valley of the Jordan and of the Dead Sea 

 is all the more important, '.that it is intimately connected, I will not say 

 with the destruction ofthe five cities ofthe plain, but with the impossi- 



* Journal ofthe Boy. Geog. Soe. vol. viii., p. 250. Jameson's Edin. Phil. Journ. vol. 

 xxix. p. 96. " Professor Schubert of Munich, two Englishmen Messrs Moore and 

 Beck, and M. J. de Bertou a Frenchman, almost simultaneously, and quite inde- 

 pendently of one another, have made the discovery that the Dead Sea and the en- 

 tire lower valley of the Jordan, are situated considerably below the level of the 

 Mediterranean Sea." 



1 Bulletin de la Soc. de Geogr. T. x. (1838) p. 84 ; and Nouv. Ann. de Voy. T. i. 

 1839, p. 8. 



I Bull, de la Soc. de Geogr. T. xii. 1839, p. 166. 



§ M. Russegger has published a dettiiled account of his labours, in Poggendorff'3 

 Annals, 1841, Numb. 5, p. 186. 



