728 Thirteenth Memoir on the Law of Storms in India. [No. 166. 



We arrive so near to the same results by all these different modes of 

 calculation, that we can entertain no reasonable doubt that they are not 

 far from the truth, as shewn by the original data, and that the vessel 

 made in round numbers 



1 . In the first two days, circles of about 1 25 miles in diameter, and 

 was sailing round at an average distance of 6l£ miles from their centre, 

 the greatest distance being 68 and the least 57^ miles. 



2. That for the last three days she was sailing round in circles of 

 about 56 miles in diameter, and consequently at a distance of 28 miles 

 from the centre, the greatest distance being 39 miles, and the least 25. 



It appeared to me also interesting to know for how many hours 

 during these five days each wind blew ; so as to obtain an idea of what 

 the total resultant curve of the winds was, independent of the run of the 

 ship. I explain these terms. By the total resultant of the winds is meant 

 in meteorology the calculating each separate wind during the number 

 of hours it blows in a given time, its direction being in nautical language 

 a course, and the time or number of hours a distance ; the strength 

 being always supposed the same (or this may also be used,) and all 

 these courses and distances, (direction and time,) may make a traverse 

 table, of which as usual one course and distance is the result. Thus if in 

 24 hours we have 9 hours of NE., and 15 of SW. wind, the resultant 

 is 6 of S W. Wind ; or the whole atmosphere of the place may be supposed 

 to have moved for 6 hours to the N. E., if the strength of the two winds 

 was always equal. This is the resultant of the wind. If instead of the 

 traverse table we project the directions of the wind for courses, and 

 the hours it blew for distances, we shall have a line of some kind, 

 which in this case is a curve, and this is the resultant curve of the 

 wind, Now in the run of a vessel scudding under bare poles her 

 run per hour may be supposed to be an indication of the strength 

 of the wind, but then, the course and distance shewn by log becomes 

 the resultant, indicating from which quarter also the resultant wind blew, 

 and this, as shewn already, is to the N. 42° E. by the log, Fig. I. 

 It is true that the vessel being always carried to the SW. by the 

 current shewn beyond doubt to have existed, this result is not so valu- 

 able as it might have been had no current existed, but it neverthe- 

 less has appeared to me to be one worth investigating, as giving an 



