1858.] Account of a Gyclone in the Andaman Sea. 325 



The Semiramis weighed anchor at noon and proceeded up the 

 river to Maulmain, where she arrived at 2 p. m. The wind after mid- 

 day gradually changed to S. W". diminishing in force. The readings 

 of the barometers, having followed a most regular course since the 

 day we had left Calcutta, showed on the morning of the 10th a re- 

 markable irregularity. The barometrical curve of the 9th had still 

 been regular, rising from 6 o'clock to 9 and 10, then falling till 4 and 

 5 p. M. and rising again in the evening. On the 10th the Mer- 

 cury rose only till 8 o'clock, when it commenced to fall, being at 

 10 o'clock much lower than it might have been expected, and nearly 

 0.200 inches lower than the day before at the same hour. (For the 

 observations on board the Semiramis as well as abstracts from the 

 logs of the ships mentioned hereafter, vide Appendix.) 



The mean barometrical pressure on the 10th (mean of hours 

 8 a. m. and 4 p. m.) was 0.15 inches lower than the mean of the 9th. 

 On the 11th, the barometer rose again, nearly to its former height 

 and returned to its regular course. The mean temperatures of both 

 days (9th and 10th) were about the same, but with a greater varia- 

 tion on the 10th. 



The concurrence of the low and irregular barometric pressure 

 and the increasing force of the wind made it very probable that a 

 Cyclone was passing near, of which we felt the extreme edge, the 

 changes of the wind being slow and the general disturbance in the 

 atmosphere not great. The change in the direction of the wind 

 having taken place from S. E. by S. to S. "W. would indicate a posi- 

 tion in the right semicircle of the Cyclone, its centre having been 

 nearest on the forenoon of the 10th. A few days after our arrival 

 at Maulmain, we obtained the confirmation of this conjecture. 



On the 12th, the survey brig Mutlah, Lt. Sweney, I. N. came 

 in, having been obliged to quit her station opposite the middle Anda- 

 man in consequence of bad weather, on the 8th April. The Mutlah 

 had the first indication of bad weather on the 7th when at anchor 

 in Diligent Straits (vide Appendix). The wind which had before 

 been blowing E. N. E. and E. S. E. the sarnie as at Port Blair, 

 changed on the 7th to S. E. with squalls and rain in the evening. 

 It will be remembered that the Semiramis experienced the same 

 change on the same day and in about the same longitude or rather 



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