192 LIEUT.-COLONEL SYKES ON THE ATMOSPHERIC TIDES 



of the 28th of February 1828, there was not any deposition of dew at Poona or in its 

 neighbourhood. Before daylight I rode thirty-four miles west-north-west to Karleh, 

 in the hilly tracts, and to my surprise found my baggage, which had been left exposed 

 during the night, dripping wet with a copious deposition. On the 1st of March I 

 reached Bombay at sunrise, and observed all the tents pitched on the esplanade satu- 

 rated with dew ; and they were nightly in this state during the period of my stay in 

 Bombay up to the 10th of March. On the 11th, at sunrise, on my return to Poona, 

 I was at Kundallah, at the top of the Bore Ghat, thirty-one miles inland from the 

 margin of Bombay Harbour, and at ] 700 to 1 800 feet above the sea. Dew had not 

 been deposited during the night of the 1 1th. On the 12th there was not any on the 

 summit of the hill fort of Loghur, near Karleh; none at Poona on the 13th of 

 March ; nor have I a record of dew again on the plains of Dukhun, unless near to 

 irrigated lands, until September, although in marching north in April and May, upon 

 the meridian of Poona, there is occasional mention of a moist soft air at sunrise ; 

 and when encamped in May on the Ghats, at Beema Shunkur, 3090 feet above the 

 sea, I was sometimes enveloped in mists rising during the night from the low land of 

 the Konkun, at the level of the sea, passing rapidly to the eastward, but entirely dis- 

 appearing by 8 o'clock a.m. The first mention of dew on the register after the mon- 

 soon of 1828 is on the 23rd of September, and it was very heavy. There was not any 

 on the 24th, 25th, and 26th. On the 27th it fell again copiously, and continued to 

 do so until the 6th of October. It then ceased until the 21st, reappeared, and 

 was deposited with occasional interruptions as in the preceding year. On the 14th 

 of February 1829 there was a remarkable fall of dew at Pait, on the meridian of 

 Poona, and thirty-two miles north of the city : with this exception there is scarcely 

 a record of dew in the whole of that month. From the 10th of December 1828 until 

 the 5th of January 1829, I was in Bombay on the esplanade ; there was a nightly 

 deposition of dew, not so copious as I had found it in April and May, but sufficiently 

 abundant on several occasions to drip from the tents in the morning. In 1829 and 

 1 830 the first dew appeared on the 6th of September in both years, and at intervals 

 afterwards as in the preceding years. These notices are sufficient to show the want 

 of uniformity in the appearance of dew. Its occurrence with an absolutely overcast 

 sky is rare ; but such was the case on the 23rd of September 1828. There are many 

 instances of its being met with under a misty sky, also under a sky chequered with 

 masses of clouds. For the most part it has been found to form most copiously in 

 clear nights ; but an inspection of my registers will show that in two consecutive 

 nights equally clear, and with trifling difference in the thermometer, one night will 

 be characterized by a fall of dew, the other not. 



I have thought these details necessary, as a knowledge of the local deposition of 

 dew, and its anomalous occurrence, is of some importance in applying the correction 

 to the specific gravity of air in determining heights barometrically ; for in the square 

 of a mile the dewing-points at Marheh on the same morning at sunrise ranged from 



