AND METEOROLOGY OF DUKHUN. 



177 



is infinitely greater at Poona than at Mahabuleshwiir or Kotagherry (it was not de- 

 termined at Hurreechundurghur), being -0884 at Poona, '0439 at Mahabuleshwur, 

 and '0430 at Kotagherry. The fourth or minimum nocturnal tide occurring in the 

 dead of night, has been rarely observed at the exact a.m. limit hour ; but the obser- 

 vations have been taken at sunrise, which is from one and a half to two hours after 

 the turn of the tide. I have previously shown that at different times I found this 

 tide to amount to —'0150, —'0254, -'0010, and +'0053, and —'0040; taking the 

 mean of these, after deducting the plus sign, we have '0134 as an approximation to 

 the amount of the oscillation in this tide ; and this corrected for a presumed propor- 

 tional increase from 4 a.m. to sunrise, would make its value '0181. During eight 

 months at Mahabuleshwur Dr. Walker found the mean fall from 10 — 11 p.m. to 

 sunrise to be -0180, thermometer — 1°'68 ; corrected to 4 a.m. it would be about '0240. 

 Mr. Dalmahoy at Kotagherry, at 6407 feet, found the fall from 9 — 12 p.m. to a little 

 before sunrise, amount to -0350 ; and as it is probable he took his observations as often 

 after the tide had turned at 10 — 11 p.m. as he took them after the limit hours of the 

 4 — 5 A.M. tide, the errors may be considered as compensating each other, and the 

 oscillation may be left uncorrected. 



Mr. Prinsep, in a voyage of thirty two days from Calcutta to Bombay, found the 

 fall of the barometer from 10 p.m. to sunrise, amount to -022, which corrected to 4 a.m. 

 would be about -0293. Correcting the rise of the tide from sunrise to 9 — 10 a.m. 

 in the same rough way, the following will be the amount of the mean oscillation 

 of the barometer in the different tides. 



The observations of Duperrey, Goldingham, and Hudson were made during the 

 limit hours of the several tides, and have not in consequence any correction applied 

 by myself. Prinsep's, Dr. Walker's and my own observations are corrected from 

 sunrise back to 4 a.m. ; but the other tides are as they were observed. Mr, Dalma. 



MDCCCXXXV. 



* Humboldt, Personal Narrative, vol. vi. part ii. page 703. 

 2 A 



