316 Meldrums Rules for the Southern Indian Ocean. [June 14. 



withm the true storm field. The difficulties and uncertainties as to 

 handling a ship in this belt are greatly increased by the facts that 

 the longer diameter of the oval form of the cyclones usually lies east 

 and west, and that there is no means of telling towards which side 

 of the oval the vortex is displaced. 



The greater incurvature of the wind in rear than in front of hurri- 

 canes in the Southern Indian Ocean is next considered, and then facts 

 are collected from other hurricane countries confirmatory of Meldrum's 

 rules for the Mauritius. 



Knipping and Doberck in the China Seas find little incurvature of 

 the wind in front, but much in rear of typhoons. 



Mr. Wilson finds in the Bay of Bengal that north-east winds 

 prevail over many degrees of longitude to the north, i.e., in front of 

 a cyclone ; and this is analogous to the belt of intensified trade so 

 characteristic of Mauritius hurricanes. 



Padre Vinez finds at Havana that the incurvature of hurricane 

 winds is very slight in front, and very great in rear. 



The author then details further researches on the nature of cyclones, 

 which bear on the rules for handling ships. 



1. Indications derived from the form and motion of clouds. It is 

 shown that the direction of the lower clouds is usually more nearly 

 eight points from the bearing of the vortex than the surface wind ; 

 but as the direction varies with the height of the clouds, and as this 

 height can only be estimated, this fact is not of much value. 



2. Looking at the vertical succession of wind currents in the 

 Southern Indian Ocean, if the march of the upper clouds over the 

 south-east trade is more from the east, then the cyclone will pass to 

 the north of the observer ; but if the upper clouds move more from 

 the south than the surface wind, then the hurricane will pass to the 

 south of the observer. 



3. As to the form and position of clouds ; so soon as the upper 

 regions commence to be covered, the direction in which the cirrus 

 veil is densest gives approximately the bearing o^ the vortex. Later 

 on, the characteristic cloud bank of the hurricane appears, and the 

 greatest and heaviest mass of the bank will appear sensibly in the 

 direction of the vortex. 



The irregular motion of the centre of a cyclone is next discussed, 

 and it is shown that the centre often twists and sways about, in some 

 cases even describing a small loop. 



From all the facts relative to the nature of cyclones adduced in 

 this paper it is shown that the attempts which have been made — 



1. To estimate the track of a cyclone by projection ; 



2. To estimate the distance of a ship from the vortex, either by 

 taking into account the entire absolute fall, or by noting the rate of 

 fall, can lead to no useful result. 



