908 Fourteenth Memoir on the Law of Storms in India. [No. 168. 



Southern Indian Ocean, p. 201, says that "in the early stages it is 

 probable the calm is very extensive and embraces several vortexes, which 

 gradually merge into one," but it will be noted that we have here a 

 " calm" of one-third of the whole space of the storm. 



The centre for the 1st of December, we can only place by calculation, as 

 to its probable position, between noon 30th, with the Caledonia, and 1 

 a. m., on the 2nd with the Hindoostan as calculated at p. 907, and assum- 

 ing it to have travelled in a straight line. It would seem that the vortex 

 expanded about this time, since it reached the Hindoostan, and being 

 deflected or flattened, no doubt, by the high mountains of Ceylon, 

 was with her not a NN. Westerly wind, which a true circle would re- 

 quire, but a Northerly wind which the coast hills would naturally 

 produce. The warmth noted by Capt. Moresby, was probably the 

 effect of the heated shores. At 1 a. m. on the 2nd, the Hindoostan 

 was at the centre and steaming through the Eastern side of it ! This 

 ship's experiment, and I do not recollect that such a one has been per- 

 formed before, gives us tolerable data for one important determination, 

 which is the whole diameter of the vortex. The diameter of the calm 

 space we cannot deduce from it, because she evidently steamed not 

 through the middle, but through the Eastern edge of the calm centre. 



If she had been far enough from the Ceylon shore for us to consider 

 the Storm Circle as quite uninfluenced by the high land, our deductions 

 would no doubt be more accurate. I have already noted that I make 

 the storm arrows on the chart to form an oval and wavy, to represent 

 this effect of the mountains, and that I consider the warm winds as 

 coming from the heated shore, and that it is owing to this deflection 

 that the Hindoostan had the wind North instead of N. Westerly, as she 

 should, and probably would, have had it in the open sea. 



We may consider her as entering upon the verge of the storm, at 

 noon of the 1st when her barometer is at 29*71, and the gale seems 

 fairly to have begun. From this time to noon the next day the log 

 marks 135 miles of run, but the true distance is 110, which proportion 

 we must use to calculate the distance run to 1 a. m. on the 2nd, when 

 the wind " lulled suddenly, and shifted round to the Southward, and 

 blew a perfect hurricane from the SE." Her run up to this time, then, 

 is by log, seventy-one miles, but the correction above noted being the 

 proportion of 135 : 110: : 71 : 58, reduces it to fifty-eight miles, which 



