898 Eighteenth Memoir on the Law of Storms. [Sept. 



from the 7th of October, there was bad weather indicating the approach 

 of a Cyclone in the N. Eastern part of the China Sea, apparently by 

 the Straits of Formosa, which by the 9th, was a severe Cyclone, in 

 which H. M. S. Childers was nearly lost on the Pratas Shoal. I make 

 the centre of this Cyclone to have been on that day in Lat. 21° 15' 

 N. ; Long. 117° 35 ; East ; and that on the following day it had 

 travelled about 285 7 to the W. b. S. Now from the position of this 

 Cyclone in the China Sea on the 9th, as given above, to that of ours 

 in the Bay of Bengal on the 12th in 17° 48' N. ; Long. 89° 81 ; East, 

 the course and distance is S. 83° W. 1530 miles, which in the 3 days 

 gives 510 miles per day or 21 miles per hour. 



If we then take this to have been the same Cyclone, it was one which 

 when raging at the surface of the Ocean in the China Sea travelled 

 about at the rate of 12 miles per hour, as by the logs of it which I 

 have ; then for three days at 21 miles per hour in the atmosphere ; and 

 then after re-descending, at an average rate of 5 miles per hour in the 

 Bay of Bengal, and in the course of its aerial track altering its route from 

 W. f S. to N. 41° West. In the change or curving of the track there 

 is nothing remarkable, as we have numerous instances of this, but it 

 seems a somewhat forced conclusion to assume at pleasure these dif- 

 ferent rates of 12, 21 and 5 miles per hour for the purpose of account- 

 ing for a supposed connection between these Cyclones. We can then 

 only note all the data as above, and affirm that our Cyclone certainly 

 descended in the Bay of Bengal, after passing over, or being formed 

 upon some land from which it brought the birds and insects. 



Rate of Travelling. 



The course and distance between the centre of the 12th and 13th is 

 N. 37° West 90 miles only, giving a rate of not quite 4 miles per hour. 

 From the centre at noon of the 13th to False Point is N. 47° West,f a 

 little more than the same distance, which it passed over between noon 

 and 11 p. m., so that we may thus fairly set down its average rate for 

 this interval of time, as 8 miles per hour, and this phcenomenon of the 

 Cyclone's augmenting its velocity as it approaches the shore is well 

 worthy of note, as in this case it was approaching a low shore with the 

 broad valley of the Mahanuddy river inland. If we compare on our Dia- 

 gram No. 4, the run of the Collingwood, overrunning the Cyclone, with 



