1839.] on the 3d, 4th, and oth of June, 1839. 587 



6th. The sixth requires none to seamen, but the unprofessional rea- 

 der should be told, that, not only from the motions of the vessel and 

 the haziness of the horizon, observations during stormy weather are 

 entitled to but little confidence, but moreover they are but very 

 seldom obtained, the celestial bodies being rarely visible ; thus the 

 latitude and longitude of the vessel is in truth but little better 

 than guessed at if she is lying to, because neither the direction nor 

 the rate of her drift can be well measured by the log, or accurately 

 known by the compass ; as it may be when scudding. Hence it must be 

 borne in mind that, though the wind may be rightly noted, the ship's 

 position may be to a certain extent erroneously laid down, and in some 

 instances upon the diagram, if the vessel be supposed to have been 

 little further to the East or West, or to the North or South, the appa- 

 rent difference will disappear. 



The Sarah in the diagram of the 4th is an instance. By the direc- 

 tion of the wind she should be further to the Eastward ; but I estimated 

 her to be where I have placed her. At 2 p. m. also, as will be seen by 

 her log, the wind veered to the Southward with her ; the centre of the 

 vortex having passed her at no great distance; the weather moderating 

 till 4 p. m. when it again came on to blow a hard gale. 



It may be observed to, and this is important, that while probably, 

 and frequently no doubt from the causes just enumerated, there are dis- 

 crepancies in the winds as laid down, these rarely, or never, amount to 

 contradictions of the theory ; which defines a hurricane to be a severe 

 gale blowing and veering round in a circular direction, while it is also 

 moving onwards. I should note also that in more than one instance I 

 have found no wind marked exactly at noon, but one at 10 a. m. 

 or 2 p. m. With this explanation of the diagrams and charts the 

 unprofessional reader will be better able to make allowance for the 

 differences he may meet with ; and all will observe how well the 

 blank which occurs on the eastern side of them will be filled up by the 

 logs of the homeward bound vessels. The description of the Map No. 

 II. belongs to Part II. to which it has reference. 



The slow rate of progress of our hurricane will not fail to be re- 

 marked. I think it probable this is owing to the vortices being pent up 

 as it were between the course of the gale and the Coromandel Hills. I 

 have further adverted to this also in Part II. 



A few more remarks on the Logs and Charts may not be without in- 

 terest, both to the unprofessional reader, and to the seaman who may 

 not at once perceive how they bear upon the theory of the circular mo- 

 tion of storms ; and that this is from East to West by the North, or 

 contrary to the hands of a watch, on the North side of the equator. 



