1849.] Seventeenth Memoir on the Law of Storms. 11 



being close to the centre, which was passing to the northward of her 

 (wind West) while the At let Rohoman, at 9 a.m. had the tyfoon of 

 excessive violence at N. E. ; and by noon it had veered to S. b. E. The 

 average change with the first of these ships we may call from N. W. 

 to S. W. giving an east course for the centre of her Cyclone, and for the 

 Atiet Rohoman from N. N. E. to S. b. E., giving a course of about 

 from S. 85° east to N. 85° W., or say a¥.}N. course and the mean 

 the two would therefore be a W. \ N. course. 



But this assumes the two ships to have been stationary like two 

 islands, whereas both ran, and were drifted considerably to the southward 

 before being drifted back to the northward. We cannot calculate this to 

 any exactness, but we may say, with all allowances, that the Cyclone 

 must really have been travelling, for them, about from E. b. N. to 

 W. b. S., which is the track I have assigned to it. We have no fur- 

 ther data for the distance it may have travelled from the eastward be- 

 fore reaching these two ships, but as it lasted a considerable time with 

 them, and was yet, by the rapidity of the veering near the centre, travel- 

 ling with considerable velocity, I have produced the track about four 

 degrees to the eastward, though it probably extended farther, and as we 

 shall see in the cyclones of 1847, may very probably have been felt, if 

 it did not fully reach to the shores of Cochin China, about Turon Bay. 



Track F. 

 Manila Tyfoon of October, 1843. 



I have for this Cyclone but a single log, though a carefully detailed 

 one, and quite sufficient to authorise us to mark off the track of it across 

 what is, at some seasons, a dangerous anchorage, and' where too much 

 caution cannot be used, whether lying at Cavite or off Manila, during the 

 whole of the tyfoon months. The extract of the log which I have is 

 contained in a letter from the Captain of the American ship Unicorn, 

 to Mr. Redfield, and by him forwarded to me. It is as follows : — 



" October 30th, 1843. — (Civil Time at Manila,*) begins calm and dark lowering 

 weather, Bar. 29.90. 3, p. m. the same ; Bar. 29.90. 4 p. m. a light breeze 

 from N. N. E. Bar. same; 6 p. m. wind veered to north, increasing dark gloomy 

 weather, Bar. 29.89. 7 p. m. thick and rainy, very sultry and has been for 24 

 hours ;felt two heavy shocks of an earthquake ; blowing fresh, Bar. 29.84 ; 9 p. m. 



* Ship then lying at anchor in the Bay of Manila ; this was the 29th by Euro- 

 pean account. 



c 2 



