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



now propose to remark on the limited and unequal extent to which 

 we can trace it distinctly as a Cyclone. 



I have given with the chart two diagrams, Nos. I. and II., of the 

 ships in their positions at noon on the 12th and 13th, with their wind- 

 arrows and the Cyclone circles correctly marked ; as also one, No. III. 

 of a supposed section of the following, or rear, half of the Cyclone in 

 the line of the track which will be subsequently explained. Taking 

 the first of these diagrams, that of the 12th, we find the utmost extent 

 which we can fairly allow it to have reached, as a Cyclone, at noon on 

 that day to the S. Eastward, or on the line of its track, is to the circle 

 marked a little without the positions of the Barham, No. 7, and British 

 Sovereign, No. 20, or about 90 miles of radius, or 180 miles of diameter. 

 Had it extended farther in this direction these ships, the commanders 

 of which were most fully prepared and anxiously watching for it, 

 would have been hove too sooner, as they were running up towards it 

 at the rate of 8 and 9 knots an hour. But we see, also, that in front, on 

 the line of its future track, the Cyclone circles distinctly extend to Nos. 

 10, 14, 21 and 19 or even to Nos. 15 and 11, the four first of which 

 ships had the Cyclone fully commenced with them, while the two last 

 were certainly on the verge of it, and this would give its semi-diameter 

 an extent of 140 miles in front, or 280 of diameter, against 90 in the 

 opposite direction or 180 of diameter. At right angles to the track 

 we have No. 8, evidently without the Cyclone circles, though just 

 approaching to them. We cannot also on this day allow that it reached 

 the Pilot or Light Vessels, but they had evident indications of it, and 

 while No. 15, the Framjee Cowasjee, at 170 miles N. N. W. of the 

 centre has a strong and increasing gale from E. b. N. and E. N. E. 

 No. 18, the Easurain at 190 miles to the W. S. W. or at right angles 

 to the track (she is not included in the diagram) has a fine N. W. 

 breeze and fine weather, moderating nearly to a calm in the afternoon. 

 On the 13th again, we perceive by the diagram No. II. that while 

 the monsoon is evidently following up the Cyclone with Nos. 7, 9, 2 and 

 17, so that we cannot to the S. Eastward allow its semi-diameter to 

 be more than 65 miles, or 130 of diameter in all ; we find that to the 

 North Westward we may without any exaggeration extend the circles, as 

 marked, to the Light Vessel and False Point Palmiras, or to 115 miles, 

 giving a diameter of 230 miles, or about in the same proportion as that 



