292 Observations on a diurnal Variation 



mercury, and with great regularity continued during tlie 

 wiiole ot tlie passage to Bombay, until our arrival in that 

 harbour on the 1 1th of January 1803. 



On January IsUi the barometers were placed on shore, 

 and did not appear in the smallest degree subject to the 

 cquatropical nrotions; although, with great regularity, they 

 had been performed while at sea, even to the day we en- 

 tered the harbour. One of the barometers was left on board 

 for a few days, and, like that on shore, seemed to have 

 no tendency towards the equatropical motions. During the 

 mouths of February and March, in Bombay, the mercury 

 was nearly stationary throughout the twenty-four hours. 

 But about the latter part of rvlarch the mercury seemed to 

 incline towards the equatropical motions in a very small 

 degree J and, during the month of April, and to the 20th 

 ot May, this small tendency of the mercury to perfonn the 

 motions appeared at tinies,. but was hardly discernible, the 

 rise and fall being of so small a quantity. From the 18th 

 of January to the 20th of May the mercury in the baro- 

 meters was in general stationary, except a very small ten- 

 dency towards the equatropical motions at times. At other 

 times somechange in the atmosphere disturbetl the mercury 

 from its stationary position : but this was seldom the case, 

 as it was then the fair weather season, or north-east mon- 

 soon. 



We sailed from Bombay on the 23d of May 1803. The 

 instant we got out of the harbour the mercury in the baro- 

 meters conformed to the equatropical motions with great 

 regularity, and the difference between- the high and low 

 stations was very considerabl-e during the whole of the pas- 

 sage to China, excepting a few days in the eastern parts of 

 Malacca strait, where the land lay contiguous on each side 

 of us : the difference between the high and low stations of 

 the mercury was then not so great as in the open sea. On 

 clearing the strait, and entering the China sea, the equa- 

 tiopical motions were performed in greater quantity, and 

 continued regular during our passage up the Chiua sea, 

 until July 2d, 1S03. We then entered Canton river, and 

 the equatropical motions of the mercury in barometers en- 

 tirely ceased. 



From July Sth to September 7th, the barometers were. 

 placed on shore in Canton, during which lime the mercury 

 appeared to have no tendency towards performing the equa- 

 tropical motions ; but it inclined to a stationary position, 

 except when influenced by changes of weather. After the 

 bar-bliiet.crs were taken from Canton to the ship, we were 

 C- '■■'-. • four 



