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



Meteorology. 



Besides the daily registry of dry and wet bulb thermometers and 

 barometers, whilst on the march, a longer series of observations was 

 made at Saugor, Bermhan, Jubbulpore and Umerkuntuk ; at Sohag- 

 pore, Allahabad, Agra and Simla. These observations seem to lead 

 to the following conclusions. 



The minimum temperature of the air was very regularly observed 

 to set in just before sun-rise, but there was never to be observed a 

 second depression of temperature immediately after sun-rise, as we 

 had observed in the Indian Seas in October, 1854. 



The increase of temperature from sun-rise up to 11 o'clock a. m. 

 is specially rapid between the hours of 8 and 9 a. i. I often no- 

 ticed an increase of temperature of 4 to 5 degrees centigrade 

 between these two hours. 



The total increase from sun-rise to 11 o'clock was, at Saugor, 

 (15th to 19fch December,) as much as 28 degrees centigrade ; at 

 Jubbulpore it was from 12 to 15 degrees ; but at Umerkuntuk (20th 

 to 26th January) the difference between sun-rise and 11 o'clock 

 A. M. was only 8| to 9 degrees centigrade. Between 11 a. m. and 

 4 P. M., the variation of temperature was generally not very great — 

 not more than 3 or 4 degrees centigrade ; but the decrease of tem- 

 perature between 4 p. m. and 7 p. m. was very rapid. 



East of Jubbulpore, at Eamgurh, and as far as Umerkuntuk, the 

 minimum temperature of the day was very near the freezing point ; 

 but I never observed a temperature lower than 32 degrees Fahren- 

 heit, or degrees centigrade. 



There was quite regularly a hoar-frost setting in, even if the mi- 

 nimum temperature of the air was 2 or 3 degrees above the freezing 

 point. The hoar-frost was produced by the great radiation of the 

 leaves and grass during the serene nights. 



At Umerkuntuk itself I observed some remarkable irregularities of 

 temperature. Considering the cold temperatures experienced in the 

 stations of the Nerbudda valley, Westward of Umerkuntuk, it might 

 be expected to find the minimum temperature of the night at Umer- 

 kuntuk below zero ; but on the contrary the minimum temperature 

 of the air on the plateau, at the end of January, was constantly 9 

 degrees and even 12 degrees centigrade above the freezing point. 



