56 
Proceedings of the Royal Society of Edinburgh. [Sess. 
VII. — The Origin of Anticyclones and Depressions. By Lieut. 
John Logie, R.A.F., M.A., B.Sc., F.R.A.S. Communicated by 
the late Capt. G. W. Jones, R.A.F. 
(MS. received October 17, 1918. Bead December 2, 1918.) 
I wish to preface this statement of my views with an acknowledgment of 
my indebtedness to the works of Major Gold, Mr W. H. Dines, Sir Napier 
Shaw, Captain Cave, and Mr Lempfert, and more especially to the sugges- 
tions of Captain G. W. Jones, R.A.F. Captain Jones was the first person to 
draw my attention to the fact that changes in the upper wind frequently 
precede changes in the lower wind. In addition, he has often expressed 
to me his conviction that the entire theory of the winds requires to be re- 
written ; that convection and surface friction are of much less importance 
than is generally supposed, and that we have no reason to regard the 
variations of the upper winds as less, either in magnitude or abruptness, 
than those of the lower winds. 
The most essential features of my theory, however — namely, the views 
that the chief cause of depressions and anticyclones is to be sought in the 
phenomenon of radiation; that the first effect of a local decrease of 
temperature is a diminution of pressure at all higher levels ; that cyclones 
are caused by cooling , and anticyclones by the heating , of air ; that clouds 
may cause winds, as well as winds causing clouds ; and that the motion of 
the air is most accelerated when depressions are dying out or anticyclones 
intensifying, — are, I believe, entirely original, as is also the detailed mathe- 
matical treatment of the subject. 
In this theory two postulates are assumed. As they are the only 
portion of it not deducible by strict mathematics from well-tested dynam- 
ical principles, I state them here for immediate criticism. 
(A) When two portions of air, differing slightly in density, are adjacent 
and in the same level, they tend to mingle and so destroy the difference of 
density. 
(B) When changes of pressure occur at any level in an extensive layer 
of air, the surrounding air does not “ immediately rush in,” but only slowly 
intrudes into the region of diminished pressure. 
Regarding the first of these, little comment is necessary. It is the 
natural consequence of gaseous diffusion aided by the small turbulent 
motions of the air. Regarding the second, the following points may be 
noted. (1) It is now many years since Major (then Mr) Gold showed that 
