1886. J illustrating the value of Cape Point as a Warning Station. 205 



varying distances outwards, equal barometric readings form a scries 

 of rings round this : the outer ring having the higfhest reading, and the 

 rest being graduated towards the centre. 



The wind does not circle round a cyclone in true circles at all 

 altitudes. 



Near the sea level the wind forms the greatest in-going angle with 

 the isobars and this angle gradually decreases, till at an altitude 

 which varies with its position with reference to the cyclone the wind 

 flows parallel to the isobars. Above this point the wind has a 

 gradual out-flowing tendency, which reaches its maximum at the point 

 where the cyclonic influence ceases. 



Below this turning point of the wind's direction, clouds are very 

 seldom seen, but when anything approaching to a cloud is foruGied, it 

 takes the appearance of fog. Hence I call this, the fog bearing 

 stratum. The next region of the atmosphere where the winds have a 

 tendency to circle outwards is the stratum of the very lowest clouds. 

 Above this is the great upper current. This current can be divided 

 into two distinct portions ; the lower, w^hich is considerably modified 

 by the direction of the cyclonic centres, and the upper portion which 

 from day to day, month to month, and year to year always flows from 

 some point near north-west, and which is in fact the true compen- 

 sating upper return current of the trade winds. 



The former of these is the stratum where the heavy cumulus and 



• cumulo-stratus cloud is formed, while the latter is the home of the 



• cifrus cloud. 



Now if the whole solid contents of a cyclone could be rendered 



visible to one situated externally to it, what would be its general 



.appearance ? I will try to make this clear. Suppose we take an 



inverted cone, perpendicular to the surface of the sea. If the apex 



(be immersed in the sea till the circle thus formed round the cone be 



.equal to the surface area affected by the cyclone, and we then cut off 



an ellipse, the one edge of which shall touch the sea and the opposite 



edge be elevated considerably above it, the solid figure contained 



between this ellipse and the sea level will be the true form of a cyclone, 



^providing you dish the surface of the ellipse towards the centre. 



The next question which it is but natural to ask is — how can you 



prove this ? A question which I will try to answer. 



I shall answer this question by asking another. Why do cyclones 



.d;ravel from west to east ? 



We often hear it said that cyclones travel round the sides of areas of 

 f2 



