1857.] Report on the Progress of the Magnetic Survey. 211 



weighing paper boxes filled with grass, sand and wool as described 

 in a former Eeport. The increase of dew the more I went to 

 the South was very considerable ; repeated observations in the 

 same places enabled me to ascertain also the variations of the 

 quantity of dew. 



There is very little variation in the daily fall of dew in the 

 Northern parts of the Punjab, but in localities close to the sea 

 the variations were very great and even remarkable without direct 

 weighing. The greatest variations of the fall of dew I observed near 

 Kurrachi, where in one night scarcely any dew fell, whilst in the 

 next the fall was excessive, although both nights were equally 

 clear and serene. 



2. — Minimum temperature of the air. 



I was particularly interested to see at what time the minimum 

 temperature of the air before sunrise takes place, and to enable 

 me to fix the time of the minimum temperature with certainty, a 

 thermometer was carefully put up and read from 5 to 5 in minutes, 

 the observations being begun long before sunrise. 



In the Punjab and in Upper Sind, during December and January, 

 the minimum temperature took place generally 30 or 35 minutes 

 before sunrise and this temperature was exceedingly well-defined, 

 never lasting more than a few minutes (confer Table A.) In Lower 

 Sind and in Kutch, however, the time of minimum temperature is 

 not so well defined ; a uniform temperature lasts nearly from 20 

 minutes before sunrise up to sunrise, the very minimum being gene- 

 rally just a few minutes before sunrise. 



A second depression of the minimum temperature after sunrise 

 was never observed. Table A shows observations on the minimum 

 temperature in the Punjaub, and Table B in Sind and Kutch. 



Table A. 



Jhung, 1st January, 1857. 

 Minutes before Sunrise. Temperature 

 (50 3-4 cent. 



50 3-4 



Mooltan, 11th January, 1857. 



Minutes before Sunrise. Temperature. 

 55 5 , 8°cent. 



50 5-4 



2 e 2 



