178 
Proceedings of the Royal Society of Edinburgh. [Sess. 
elevation seem to suggest that the air in the stratosphere will tend to 
flow from the areas over anticyclones to those over cyclones, and that 
some exchange of air may take place between the two systems in the 
isothermal layer. 
If the above represents the true condition of matters in the cyclone, 
it is evident it is not in accordance with the generally received ideas. If 
it is correct, then the cyclone must receive energy from outside sources. It 
is of course known that it uses up the latent heat of the vapour it carries 
up with it from the earth. Further, it will absorb more heat from the 
sun than does the anticyclone, owing to the presence in it of mole clouds 
and more water vapour. But it is not easy to say whether or not the heat 
from these sources is sufficient. 
There are two points connected with the temperature observations of 
the upper air to which I wish briefly to refer. First, there is the accuracy 
of the balloon records. Observations taken in anticyclones during the day 
will likely give too high readings of the thermographs, owing to the greater 
amount of sunshine in anticyclones than in cyclones. If we cannot avoid 
getting readings two or more degrees too high in screens in sunshine at 
low level, the balloon instruments are likely to have a still greater error, 
which will be greater in the anticyclone than in the cyclone, where they 
will be less exposed to sunshine owing to the greater cloudiness, and where 
they will also be exposed to an occasional wetting, which will still further 
lower their readings. These considerations seem to point to the probability 
that the temperature in cyclones is not so much lower than that in anti- 
cyclones as the observations indicate. 
The second point to which I wish to refer is that, in the table of tem- 
peratures referred to, no readings at the earth’s surface are given : the 
table begins with temperatures at 1 kilometre above the surface. Now, 
according to the convection theory, this lower stratum under 1 kilometre 
plays a most important part, as it is there that the start of the cyclone is 
made and from it much of its energy is drawn. These last words naturally 
cause us to ask the question : If we must abolish the convection theory of 
cyclones, where are we to find a source of energy sufficient to drive the 
winds? We can hardly expect to find it in the highly attenuated atmo- 
sphere under the troposphere. 
Notes on Cyclonic Motion. 
The following notes on cyclonic motion may be useful in helping us to 
understand what is taking place in cyclones. Let us take a vessel, say an 
ordinary washhand basin, with an outlet in or near the centre, and fill it 
