AND METEOROLOGY OF DUKHUN. 167 



BOLDT, on the authority of Horsburgh, has been led into the expression of a belief 

 that they are masked or suspended on the western coast of India during the pre- 

 valence of the south-west monsoon. I am, however, enabled to state that this is 

 quite unfounded with respect to Dukhun, as they were never interrupted, even for a 

 single day, during six monsoons ; and the same fact was observed at Kotgherry on 

 the Neelgherry mountains at 6407 feet above the sea during part of the monsoon of 

 1828. Of their occurrence on the coast I am also enabled to offer some evidence 

 from registers kept at the Engineer Institution in Bombay, and regularly transmitted 

 to me ; but the hours selected for observation, 9 noon and 3 p.m., were not exactly 

 adapted to fix the full amount of the tide ; but on the whole the fact of their oc- 

 currence during the monsoon of 1829 in Bombay is undeniable; and they were 

 similarly remarked at Calcutta in 1822 by General Hardwicke, and by Mr. Prinsep 

 in 1829, 1830, and 1831. This fact will relieve Humboldt from some of his diffi- 

 culties in his reasoning on the tides. 



With respect to the tides in general, I have to state that in many thousand obser- 

 vations made by myself there was not a solitary instance in which the barometer 

 was not higher at 9 — 10 a.m. than at sunrise, lower at 4 — 5 p.m. than at 9 — 10 a.m., 

 whatever the indication of the thermometer or hygrometer might be : nor was there 

 a solitary instance in the year 1830 in which the maximum night tide was not higher 

 than the 4 — 5 o'clock day tide, although it rarely, if ever, rose so high as the 9 — 10 

 a.m. day tide. The nocturnal minimum tide occurring at 4 — 5 a.m., from three to 

 four hours after my usual time of retiring to rest, my observations of it were very 

 limited in number; nevertheless the accompanying Tables will furnish some direct, 

 and ample indirect, testimony of its existence, since the fact of the rapid, constant, 

 and considerable rise of the barometer from sunrise until 9 — 10 a.m. justifies the 

 inference that there must have been a considerable previous fall to have admitted of 

 such rise : the commencement of such fall was necessarily observed by me in my 

 labours during 1830 to determine the limit hours of the tides, as I was obliged to 

 continue observing in each case until the tide had turned. Moreover, at different pe- 

 riods I devoted forty-nine nights to the investigation of the minimum a.m. tide. 

 Dr. Walker at Mahabuleshwar, at 4500 feet above the sea, bestowed eight months' 

 labour upon the tides ; and Mr. Dalmahoy, on the Neelgherry mountains, was simi- 

 larly employed for four or five months. Humboldt in his narrative mentions the 

 determination of the extent of the diurnal oscillations, the duration of the stationary 

 state of the barometer at its maxima and minima, and the exact periods at which it 

 becomes stationary and is in action again, as desiderata. I shall take these subjects 

 in order as I proceed. 



The extreme oscillation of the barometer in the same day never amounted to two 

 tenths of an inch, in fact to '1950, with a difference of the attached thermometer 

 during this range of -h7°'6, and the hygrometer 15° from the point of saturation. 

 Wind light and variable. This took place on the 19th of April 1830. There were 



