326 A Twenty-first Memoir on the Law of Storms, [No. 4. 



W. N. W. ; at 2h. 41' a. m. and W. S. W. at 3h. 4i' a. m. giving 

 us, as a mean, the wind at West (centre due North of Madras)at 3h. 

 10' a. m. The Bar. is marked as having reached the minimum of 

 29.316 at 5h. 36 / a. m. ; hence at Noon and no doubt because of the 

 closely following monsoon, we find all the winds between S. E. b. S. 

 and S. W. and we have no inland reports from which even approxi- 

 mately to deduce the position of the centre, if there was one, and it 

 is not at all unlikely, that even the low range of the Pulicat hills 

 over which the Cyclone must have passed was quite sufficient to make 

 its various movements so irregular that but little could safely be set 

 down except from a very considerable number of careful local reports 

 such as are obtained in America or England. I am inclined indeed to 

 think that its action was much disturbed in the neighbourhood of the 

 land on account of the great discharge of lightning which took place 

 with some of the ships. 



If we take the centre of the Cyclone to have " landed" some 30 

 miles due North of Madras at 3 a. m., this will give it a course of N. 

 56° "West, 115 miles for the 15 hours, from the place of the centre on 

 the 4th, and for the 24h. will give 184 miles on the same course to 

 Noon placing the centre in Lat. 14° 12'; Long. 79° 49' As before 

 remarked this acceleration of rate and change of course on the approach 

 of the Cyclone to land is by no means new to us having been frequently 

 traced before by authentic reports. 



I have not thought it necessary to mark on the Chart the runs of 

 the ships from Madras Roads ; the positions of one or two for the 4th 

 and 5th are given, being referred to in their logs. 



There are some peculiarities in this Cyclone worth remarking upon 

 and the first of these is the remarkable — 



Vibration of the Wind. — We find this phenomenon to have 

 occurred not when the ships were close to the centre where the incurv- 

 ing of the wind-spirals (like that of the arrows on the vignette of some 

 of the Charts) is to be expected, but at a considerable distance from 

 the centre and even before we can affirm the Cyclone to have truly 

 commenced, and this again to have occurred with the same ship for 

 several days. Thus taking the ships in the order they are set down 

 in the Summary, we find on the 1st May the ships and winds as 

 follows : — 



