of Edinburgh, Session 1880-81. 
209 
Monday, 2 d May 1881. 
Professor MACLAGAN, Vice-President, in the Chair. 
The following Communications were read : — 
1. On the Classification of Statistics. Part III. — Results. 
By Mr Geddes. 
2. On the Motion of a Storm in an Easterly Direction 
being only possible as a Circular Atmospheric 'Wave. 
By Robert Tennent. 
It is here intended to show how a storm with a diameter of 
several hundred miles, and with a comparatively low vertical height, 
can move and only in contact with the resisting surface of the 
ground, but not on a‘ frictionless surface. Exceptional cases are all 
here received owing to the complexity of the subject, and also to 
the comparatively few conclusions which have been arrived at in 
the millions of observations which have taken place. Let this 
storm be supposed to be inaugurated in the United States, and be 
described as being a vast mass of rarefied air enclosed within its 
surrounding isobarics. In this form, as is well known, it does not 
cross the Atlantic and to the British Isles ; it only alters its position 
in the form of a circular-atmospheric wave, and by the “ Curve of 
Outward Propagation” in front, described in the paper of 1877-78, 
page 574, and which is accepted by a well-known continental mete- 
orologist. As shown by the Rev. W. Clement Ley, cirrus clouds 
aloft move in front and from low to high pressure. This also 
takes place with the Curve, which, by the alteration of the position 
of the atmosphere aloft, may thus probably produce these clouds. 
Opening out of a storm in this way in front, of course fills up in 
the rear. To enable this to take place, it is of course accompanied 
by a spiral inflow to its low centre, and with the important and 
necessary motive force of the central ascending current, on a resist- 
ing but not on a frictionless surface, as exhibited in the diagram 
of the ascending balloon. Spiral inflow differs in its direction, 
and also with its source of supply in the different segments ; how 
can a depression then remain stationary 1 It is shown to move in 
