1840.] 



and Mountains of N. W. India. 



(553 



As instances of the very gradual rise and fall of the thermometer from 

 hour to hour, as well as of the little diminution of heat during the night, 

 the following observations are subjoined, which were all carefully made 

 in the open air, and on clear sunny days, but in the shade : — 



Time. 5. 6, 7. 8. 9. 10. 11. 12. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12, 



April 19 58 — — 70-5 76-5 77 76 75 76 — 67*69 — 60 



„ 21 59 62 65-5 72 74-5 74-5 73-5 73-5 71-5 71-5 72 71 5 68 65 64 62-5 + — 



May. 6 53-5 58-5 63 68 75 75 75-5 76 75-5 72 66* 70 69 — 64 58 



Sept. 29 57 59 60 61 — 69 — 69 — — — 66 64 60 * — 



The transition to the rainy season is not accompanied with so great a 

 diminution of temperature as might be expected. In the year 1829, 

 the rains came on on the 15th of June. The mean temperature of the 

 two previous days were 67° and QS'^, while that of the twenty-four hours 

 subsequent to the rains was 62°, and that of the whole day of the l6tli 

 was 63*5 



A thermometer hung up in the sun, and freely exposed to its influ- 

 ence, as well as to that of the air, was usually from 5° to 10° higher; 

 the maximum generally taking place about 12. 



Atmospherical pressure is also very equable; but the observations 

 have not all been made with a stationary instrument, nor all at the same 

 place in the hills. At the top of the range, where the houses were 

 first built, the barometer observed in September, October, December, 

 and April, did not differ at these various times more than one-tenth of 

 an inch, or from 23-60 to 23 -.50. Mr. Boulderson has published his 

 observations in another part of the same range, called Caineville, from 

 I5\h. May to 21st of November: he has 24*158 as the maximum mean 

 of seventeen observations, from 1st to 21st Nov., at 10 a. m., while 

 23-815 is the minimum of twenty-two observations in June, at 4 p. m., 

 giving a range of "343 inches. 



The daily periodical fluctuation was observed to be as regular in the 

 hills as in the plains. The maximum height to which the barometer 

 rose was always about ten o'clock, and the lowest to which it fell, about 

 4 p. M. 



From the equability of temperature as well as of pressure, we might 

 also expect considerable equability of evaporation ; bist if it were not 

 for the increased capacity of air for moisture, as well as for caloric, in 

 proportion to its rarefaction, the climate w-ould be a very moist one, as, 

 indeed, is the case in the rainy season. From my observations, how- 

 ever, it appears, that there is always a moderate degree of evaporation 



Cloudy. 



-V 57-55 next morning. 



t 56 next morning, at day break. 



