The Winds of Kimberley... 2. gis... +; 89 
necessarily so under existing conditions. For consider what goes on 
in the vicinity of the sub-solar point.. The air here near the ground 
is being heated with great rapidity and is expanding in all directions 
outwards and upwards. Before the process, however, has gone 
sufficiently far to allow the lower air to expand enough to set up 
an outflow overhead and a convection current, below, the sub-solar 
poimt has shifted to the west, the motive power is on the decline, and 
hence only the beginnings of the establishment of convection currents 
are ever manifested. The pushing-out process may be expected to 
make itself felt right up to the borders of the great circle of which H 
is the pole; and it is worthy of note that the greater, maximum of 
the barometric tide shows itself on the western edge of the same 
circle, the lesser maximum falling some 30° behind the eastern edge. 
Throughout the space containing H, lying between these two tidal 
crests, the wind variations are in perfectly regular sequence. 
In the cold hemisphere we have, to start with, an opposite state of 
things. At the cold spot C the air is contracting inwards and. down- 
wards, but with far less intensity than the expansion near H. By 
first intention, then, the expanded air will tend to move into the cold 
hemisphere. The contraction increases the pressure at the cold 
spot, being aided, perhaps, by the greater barometric crest: lying 
some 40° away. The greatest effect of the contraction will therefore 
make itself felt not at C, and still less towards 8’, but further to the 
west. In sympathy with this the lesser crest which might. have 
remained on the border of the warm hemisphere moves eastward 
until the gradients on each side of the lesser minimum are equalised. 
It must not be thought that I am trying to manufacture a satisfactory 
explanation of the cause of the barometric tides; the important fact 
to be insisted upon is that the circulation, ered about H is 
developed well into the cold hemisphere by the asymmetry ‘of the 
barometric maxima and by the contraction in front of C. Once there 
the directions will shift normally as in a clockwise, circulation in 
consequence of the tendency to an indraught about the depleted 
space. The deflecting force is no doubt small, but on the other 
hand the winds are light, and hence the more easily turned. With 
stronger currents the right-handed gyration about C would be much 
less pronounced—always supposing the motion imparted from the 
outside—and this it seems explains why, when at 11 p.m. the wind 
velocity attains its second maximum, the wind directions tend to fly 
off centrifugally from the right-handed gyration. The straight arrow 
in the figure is an attempt to represent this. It stands for the’ intru- 
sion of the abnormal maximum frequency. of easterly winds, about 
11 pm. The actual depletion to the west of C will. depend. more 
