1839.] on the 3d, 4th, and 5th of June, 1839. 643 



has two motions, the one a turning or veering round upon a centre, 

 and the other a straight or curved motion forwards, so that it is both 

 turning round and rolling forward at the same time. It appears 

 also that it turns, when it occurs on the North side of the Equator 

 from the East, or the right hand, by the North, towards the West ; or 

 contrary to the hands of a watch ; and in the Southern hemisphere, 

 that its motion is the contrary way, or with the hands of a watch. 

 The foregoing memoir with the charts and diagrams shew that this 

 rule holds good at least for our storm of June last ; and that the wind 

 was really blowing in great circles in a direction as described ; i. e. 

 against that of the hands of a watch. We assume then for the pre- 

 sent, that the hurricanes in the Bay of Bengal always follow this 

 law. We do not yet positively know that such is the case, but it is 

 the most probable opinion. 



If we describe on a piece of paper a few concentric circles, like those 

 in the diagrams, and marking a little compass with its fleur de lis to 

 the North in the middle make four arrows at the top, bottom, and 

 two sides, writing against them as in the diagram, East- wind, North- 

 wind, West- wind and South- wind, and then cut this out with scissors, 

 we shall have what is called a Hurricane-circle or Hurricane-card. 



The use of this is to lay it down upon any part of a chart. We may 

 also cut out a little spindle-shaped piece to represent our ship, and 

 place this in that quarter of the card at which the wind is found. 



The card may be supposed to represent a circle of fifty or of five 

 hundred miles in diameter, as we please ; and one which would fill up 

 the head of the Bay of Bengal would show, on our map No. II, the 

 wind South on the Arracan coast, East at the Sand-Heads, North on 

 the coast of Coromandel, and West across the Bay. 



We have now to judge of three important points, What is the track 

 of the hurricane if it is to be one ? In what direction does it bear from 

 us now? How far are we from its centre? 



We do not yet know what is theusual track of our Indian hurricanes. 

 We know from Col. Reid's and Mr. Redfield's researches that those of 

 the West Indies begin about the Leeward Islands, travel to the WN W. 

 and then round the shores of the Gulf of Mexico, and following the 

 Gulf Stream, are lost in the Atlantic between the Bermudas and 

 Halifax ; and they have investigated a sufficient number to show that 

 this may be taken as a general rule. Those also of the Mauritius 

 seem to come from the Eastward. All we yet know positively here is 

 the course of this single tempest; and hence the great necessity of 

 further observation and research, to which I shall perhaps farther 

 allude. We may however, in the absence of better knowledge, take it as 



