CYCLONES. 145 
velocity, varying from ten to fifty miles an hour. Further, the 
direction of this movement will in the greater number of cases, 
be from the west, or south-west, towards the east, or north-east. 
Sometimes they move from the north to the south, less frequently 
from the south to the north, and only rarely from east to west. 
Figs. 5 and 6, Plate I., show very clearly the progression of a 
Cyclone from west to east. During the twenty-four hours which 
divides the time between the two maps, it will be noticed that the 
Cyclone has advanced about five hundred miles, that is, that it 
must have been travelling at the rate of twenty-one miles an hour. 
Another point of great importance is to be noticed on the 
weather-maps. I said a little time ago that the strength or 
velocity of the wind was marked on these charts by differences in 
the drawings of the arrows. Now, if we look at the arrows in 
Fig. 3, Plate I., we find those between the lines of barometric 
pressure, which approach the closest to each other, show that 
_ there the wind is blowing stronger than where the lines of pressure 
are more widely apart. This is a general law with Cyclones, ‘ that 
the closer the lines of barometric pressure approach each other, 
the wind blows with greater force.” 
The weather maps teach another invariable law about Cyclones, 
and that is that the wind always blows round them in one par- 
ticular direction, that direction being (as viewed in our maps) 
in an opposite direction to the way the hands of a watch turn. This 
law of the direction of rotation of the wind round an area of low 
‘pressure, or Cyclone, is a most important one to bear in mind. 
For instance, it enables anyone when out in a storm of wind to 
find out in what direction the centre of low pressure in the 
‘Cyclone must be. Let us look at this map (Fig. 3, Plate I.) and 
‘imagine ourselves near a wind-arrow on the right hand side of the 
Cyclone, and standing so that our Jacks are towards the wind. 
Then you will notice that the area of lowest pressure lies on our 
left-hand side. Now lét us imagine ourselves on the left-hand 
‘side of the Cyclone, still with our backs to the wind ; here again 
ou will notice that the lowest pressure is still to our left-hand ; 
indeed, you must easily see for yourselves that in whatever part 
; II 
