ANNOTATIONS AND ADDITIONS. 79 



No portion of the so-called Desert of Gobi (parts of 

 which contain fine pastures) has been so thoroughly 

 explored in respect to the differences of elevation as the 

 zone, of nearly 600 geographical miles in breadth, between 

 the sources of the Selenga and the great Wall of China. 

 A very exact series of barometric level! ings was executed 

 under the auspices of the Academy of St. Petersburgh by 

 two distinguished Savans, the astronomer George Fuss, and 

 the botanist Bunge. In the year 1832 they accompanied 

 the mission of Greek monks to Pekin, to establish there 

 one of the magnetic stations recommended by me. The 

 mean height of this part of Gobi does not amount, as had 

 been too hastily inferred from the measurement of neigh- 

 bouring summits by the Jesuits Gerbillon and Yerbiest 

 to from 7500 to 8000 French (8000 to 8500 English) 

 feet, but only to little more than half that height, or 

 barely 4000 French or 4264 English feet. Between Erghi, 

 Durma, and Scharaburguna, the ground is only 2400 French, 

 or 2558 English, feet above the level of the sea, or hardly 

 300 French (320 English) feet higher than the plateau of 

 Madrid. Erghi is situated midway, in lat. 45 31'., long. 

 111 26' E. from Greenwich. There is here a depression 

 of more than 240 miles in breadth, in a SW. and NE. 

 direction. An ancient Mogul tradition marks it as the 

 bottom of a former inland sea. There are found in it 

 reeds and saline plants, mostly of the same kinds as those 

 on the low shores of the Caspian. In this central part of 

 the desert there are small salt lakes, from which salt is 

 carried to China. According to a singular opinion very 



