I50 PROCEEDINGS COTTESWOLD CLUB 1905 
swirls and waves of motion, not necessarily extending to 
the surface, of which fluctuations we, living, as it were, at 
the bottom of a sea, can only judge by such knowledge as 
is attained by the observation of varying pressures shown 
by the barometer, and of changes in temperature shown 
by the thermometer, at the earth’s surface, at sea level, on 
mountains, by balloon ascents, by kites, the explosion of 
shells into upper currents, and the observation of cloud 
movements, and in mines below the surface. 
Without attempting any description of the general cir- 
culation of atmosphere over the surface of the globe, 
it may be sufficient for present purposes to refer to two 
main principles: that at the equator the atmosphere is” 
warmed, and at the poles it is cooled, and that a stream of 
warm and lighter air is always flowing from the equator to 
the poles, and of cooler and heavier air from the poles to 
the equator, and that these currents are deflected by the 
varying velocities of the movements of the surface of the 
globe, which vary from over 1000 miles an hour at the 
equator to nothing at the poles. In this way a current 
starting from the North Pole and moving southwards, as it 
comes over a part of the globe travelling at 500 miles 
an hour, lags behind increasingly, and tends to become a 
north-east wind, and a warm current starting from the 
equator and moving northwards, at once and decreasingly 
lags behind, and is converted into a south-west or west 
wind. 
Air starting southwards in latitude 25° N. moves east- 
ward with the same velocity as that part of the earth's 
surface, but passes in its course over places travelling at a 
much greater rate, and is thus overtaken by them, and 
seems to come from the E. of N. 
In the same way, when a steamship is travelling due east 
on its passage from Dublin to Holyhead, and the wind 
