346 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



At the May meeting (1878) of the Russian Geographical 

 Society, M. Potanin gave an account of his recent travels in 

 Mongolia. He states that the Mongolian or Altai range of 

 mountains is separated from the Tian Shan range by the 

 Gobi depression; and that the main body of the mountains 

 has the character of a continuous plateau without culminat- 

 ing summits ; and that its passes, the lowest of which is 8000 

 feet above the sea-level, are separated from each other by 

 deep ravines. 



Detailed topographical information was given by M. Po- 

 tanin regarding a portion of the Altai Mountains, and inter- 

 esting particulars regarding the population. 



Colonel Przewalsky is preparing for a second journey to 

 Lob Nor, and intends to reach Lhassa by the Hami and Sha- 

 chan road, a most arduous undertaking. Colonel Przewal- 

 sky will be accompanied, as before, by Lieutenant Eklon, and 

 bv an artist. 



mi 



The reports of the Great Trigonometrical Survey of India are 

 always interesting, and the volume recently issued (1876-77) 

 is more so than usual, as containing an account of the con- 

 solidation of the three hitherto independent surveys the 

 Great Trigonometrical, the Revenue, and the Topographical. 

 The amalgamation now being carried out under the direc- 

 tion of Colonel J. T. Walker, R.E., Surveyor-General of India, 

 will enable any officer to be transferred from one post or sur- 

 vey-party to any other, and will doubtless conduce to greater 

 efficiency. 



Since 1845 more than 800,000 square miles, comprising 

 more than one half of British India, have been surveyed 

 and mapped. As in the case of our own Coast Survey, it 

 has been found that the latitudes and longitudes determined 

 astronomically differ sensibly from the geodetic determina- 

 tions. 



The remeasurement of the southern portion of the great 

 Indian arc and its extension to a length of 24 have furnished 

 Colonel Clarke, R.E., with data for a fresh determination of 

 the figure of the earth. As the data are added to, Colonel 

 Clarke finds that the fraction expressing the earth's ellipticity 

 becomes larger, the value obtained by Airy and Bessel, forty 

 years ago, being tt, 1 , *, which was replaced by -^-^ on the com- 

 pletion of the English and Russian arcs in 1858; and the re- 



