50 Fifteenth Memoir on the Law of Storms. [Jan. 



lifted up and (if the Cutch storms were any renewal of it) have again 

 descended there,* as a moderate though still circular-blowing gale. 



Kate of travelling. — Having thus settled the track of the storm, we 

 have to investigate its rates of travelling. It will appear from the 

 Chart that these are as follows : — 



Track. Distance. Rate p. hour. 

 Miles. Miles. 



Noon 16th to Noon 17th April N. 8° E. 180 7.5. 



17th 18th N. 15oW. 220 9.2. 



This last track does not agree with the shift experienced by the Buck- 

 inghamshire, which was from the E. S. E. to the W. N. W., and which 

 would give a track of N. 22° E. ; but first, ours is an average track for 

 the 24 hours, and next the ship was drifting about for two hours in 

 the calm centre,*}* so that we cannot say to which part of it she was 

 carried. We must also take into account her being just dismasted, 

 with both masts hanging to her side and beating under her bottom, 

 which had to be cut away : and when life and death were hanging on 

 the successful execution of this duty, it may fairly be doubted if the 

 direction of the wind was correctly noted, or rightly recollected by any 

 one? 



The track given for the H. C. S. Essex is, it is true, laid down from 

 her shifts of wind also ; but this was an immediate shift or rapid veer- 

 ing without any calm interval, and it took place five hours after she wa 

 dismasted, and the wreck was cleared from the sides quickly after the 

 accident ; she had besides the complement of six officers, which the 

 Company's China ships in those days carried, and thus there can be little 

 doubt that her winds are correctly given where marked, and that the 

 track of her hurricane is to the N. N. W. 



The rates of travelling of the Cleopatra's hurricane are quite within 

 the limits at which our Indian hurricanes have been shown to progress, 

 and do not call for any particular remark. 



* In my new work I have, I think, shown satisfactorily, that hurricane storms are 

 mere disks of from 3 to 10 miles in height, and that it is much more than probable 

 that they are formed above and descend ; and we have instances on land, though not 

 at sea, of their rising up and re-descending. 



t Taking the calm to have lasted two hours and the hurricane to be moving on, as we 

 have seen, at the rate of 9.2 miles per hour this gives about 18^ miles for the diameter 

 of the central calm space. 



