AND METEOROLOGY OF DUKHUN. 171 



Of the rise of the barometer from sunrise to 9 — 10 a.m. I shall say only a few 

 words, as the period embraces but four sixths of the time occupied by the flux of 

 the atmospheric tide, and the figures in consequence are of little further value than 

 as affording presumptive evidence that the rise, without the exception of a single day 

 for six years, must have been preceded by a nocturnal ebb. Although the annual 

 means, -0473, difference of thermometer attached +7°-27, for 1827 ; -0481, thermome- 

 ter -j-6°71,for 1828 ; and '0382, thermometer +7°*48, for 1829,agree tolerably well, yet 

 the monthly means for successive years do not manifest the same accordance ; as in 

 the tide just noticed the smallest mean oscillation is in the monsoon months, and it 

 increases until December — January, and then decreases to June — July. In 1828, how- 

 ever, June is a remarkable exception, the oscillation being greater than in any month 

 of the year excepting January, and nearly double that of June 1827. Dr. Walker 

 at Mahabuleshwur, at 4500 feet, found the rise from sunrise to 9— 10 a.m. to be nearly 

 identical ('0476, thermometer +4°- 18) with my rise at less than 2000 feet. Mr. Dal - 

 MAHoy at Kotagherry, at 6407 feet, found the rise from sunrise to noon to be -0490, 

 thermometer 4-10°-4 ; and had his observations been taken at the hour of the maxi- 

 mum diurnal tide (9 — 10 a.m.), the oscillation would no doubt have exceeded those 

 recorded by Dr. Walker and myself at infinitely lower levels. Mr. Goldingham at 

 the Observatory at Madras, a little above the level of the sea, makes this tide amount 

 to '0470 ; so that, in fact, it is less at the level of the sea than at 6407 feet ! 



The nocturnal rising tide from 4 — 5 p.m. to 10 — 11 p.m. I observed with great care 

 for eleven months continuously in 1830. It amounted to -0884, thermometer — 7°-2. 

 The indications of monsoon influence in this tide are scarcely perceptible. Indeed, 

 the smallest monthly mean oscillation occurs in December, "0450, thermometer — 6°*3 ; 

 and the greatest in May, '1140, thermometer — 9°*0. Unlike the preceding tides, we 

 cannot trace a maximum in the coldest months, and a minimum in the most rainy. 

 Dr. Walker found it to amount to '0439, thermometer — 5°*58 ; the monthly mean 

 maximum oscillation, '0632, thermometer — 3°*21, being in November, and the mini- 

 mum, *029 1 , thermometer — 6°'74, in January. Mr. Dalmahoy, at 6407 feet, found it to 

 be '0430, the minimum, "0280, being in June, and the maximum, '0560, in April ; but 

 as he did not determine the exact period of the time of the tide between 9 — 12 p.m., 

 the real extent of the tide is unknown. In my own observations I watched for the 

 turn of the tide. Mr. Goldingham, at Madras, makes the value of this oscillation 

 •0630 ; whilst M. Duperrey, at Payta in America, latitude 5° 5' S., makes it -1259. 



I now pass to the fourth tide, the fall between 10 — 11 p.m. and 4 — 5 a.m. Here 

 the data are defective, as observers have only, for very short intervals of time, en- 

 deavoured to fix its limit hours ; and I have no reliance whatever upon occasional 

 observations as types of a whole year, or even a month or week. For myself, I am 

 not an exception, as my observations between 4 — 5 a.m. are very limited in number. 

 The maximum night tide, I have before stated, was observed by me for eleven 

 months, and the a.m. tide at sunrise for several years. Dr. Walker, at Mahabu- 



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