BAROMETRICAL VARIATIOW, 21 



*brm the equatropical motions, from September 13, 1803, Tropical varia. 

 'the day we cleared the river of Canton, until Oclober i^, „^^t„, 

 ■when we entered Sincapore Strait, excepting a fmall degree 

 of irregularity, which affecled the mercury on the 22d Sep- 

 tember, wiien it blew a gale on tlie coaft of Mompa. 



06lober 13, 1803. On entering the Strait of Sincapore, 

 which is about Sf leagues wide, the mercury in the barome- 

 ters was then a little -obftrufled, and did not perform the 

 equatropical motions, in the fame quantity of rife and fall, as 

 when we were in the China Sea. But on the following day, 

 O6lober 14, when we had patfed the narrow part of the Strait, 

 the mercury conformed to thofe motions with regularity until 

 O6lober 21, when we arrived in the harbour of Prince of 

 Wales's Ifland; then a great retardation took place in the 

 equatropical motions; for, during the time the (hip remained 

 in the harbour, from 06tober 20 to November .5, 1 803, the 

 mercury in barometers teemed only in a fmall degree fubjedl 

 to them, the difference between the high and low ftations of 

 the mercury, being in general not more than half the quantity, 

 that takes place in the open fea, or at a confiderable diftance 

 from land. Where the fhip lay at this time in the harbour, 

 the land, on one fide, was a full quarter of a mile diHant, and 

 on the other fide about l| mile. 



On November 5, being cleaf of the harbour of Prince of 

 Wales's Ifland, the equatropical motions were inftantly per- 

 formed by the mercury, in the ufual quantity experienced at 

 fea, which continued with uniformity until December 3, On 

 this and the following day, the mercury fell confiderably 

 during our pafTage over the tails of the fands at the entrance 

 of floogly river, in latitude 21* 06' N ; and on December 5, 

 the day of the moon's lafl quarter, a gale of wind commenced 

 from N N E, with much lightning and rain in the night. 

 During the latter part of this day, the mercury began to rife, 

 and there foon followed a change of fettled weather. When 

 we were in the lower part of the river, the mercury appeared 

 to conform in a fmall degree to the equatropical motions ; but 

 when well up the river, at Diamond Harbour, the mercury 

 inclined to be nearly flationary during the 24 hours, as has 

 formerly been obferved to happen in Canton river, Bombay 

 ferbour, &c. 



On 



