CO Report on the Progress of the Magnetic Survey. [No. 1. 



The temperature of water in wells, which are but little used, is 

 considerably cooler than that of wells from which water is con- 

 stantly drawn, as the cold air which sinks down during the night 

 into the wells cools stagnant water much more than it can do the 

 water of wells which is constantly removed. 



As a curious phenomenon connected with Physical Geography, 

 I finally beg to mention the way in which the jungles are distributed 

 in Central India. 



The base and slope of the hills, and the valleys between them, 

 are generally covered with very dense and extensive jungles, but 

 the summit of the flat hills and small plateaux which occur in many 

 localities, are nearly always quite bare and destitute of trees and 

 jungly vegetation. I had been informed by my brothers, that this 

 very curious phenomenon occurs all along the Southern parts of the 

 Khasia and Jynteah Hills, and on the plateau of the Neilgher- 

 ries. 



This phenomenon seems to be due, in part, to the very strong 

 winds which sweep over those isolated plateaux and which evident- 

 ly must be very injurious to jungle vegetation. Another impor- 

 tant cause is, the want of moisture in these isolated plateaux. 



The geological results obtained in the journey from Agra to 

 Saugor will be contained in the Report which my brother Adolphe 

 will have the honour to submit to Government ; I shall therefore 

 content myself by mentioning some geological results to which the 

 investigation of the country visited by me alone seems to lead. 



In the valley of the Nerbudda some interesting deposits of fossil 

 remains occur. The larger deposits are found from Bermhan up 

 to Mundlah, the bones are found in a brown alluvial clay, and 

 belong to species of elephants, rhinoceros, hippopotami, buffaloes, 

 &c. I also found with the bones well preserved fossil shells of 

 Unio, Melania, and other fresh-water species. A comparison of 

 these fossil shells with those now living in the Nerbudda, and in 

 various tanks of Central India, of which I collected a large number, 

 will assist in determining the geological age of the fossiliferous 

 deposits of the Nerbudda valley. 



From Jubbulpore to Umerkuntuk the prevailing rock is black 

 trap, identical with the trap of the Deccan. 



