430 SECTIONAL TRANSACTIONS .—A. 
Friday, September 8. 
PRESIDENTIAL ApprEss by Sir G. T. Waker, C.S.I., F.R.S., on Seasonal 
weather and its prediction (10.0). (See p. 25.) 
Prof. F. Linxe.—The influence of the stratosphere on cyclone formation 
(11.0). 
The Norwegian polar-front theory stands in contradiction to the opinion 
of several German and Austrian meteorologists, in that the formation and 
movement of cyclones are produced by inertia or gravitational waves in the 
stratosphere. 
The wave movements originating on the fronts of the troposphere are 
insufficient to explain the energy produced thereby. 
The following facts speak for independent stratospherical waves : 
(1) On all stratifications with sufficiently great density gradients inertia- 
waves can originate, therefore also in the tropopause. 
(2) By means of isallobar maps one can study the course of very expansive 
wave systems right round the earth, which do not agree with the movements 
of the cyclones and even intersect them. ‘These wave systems must have 
their origin in the stratosphere. It is observed that fronts which are 
becoming stationary again become activised by such waves. 
(3) According to the Norwegian view, on the ground, cooling must be 
connected with rising air pressure and decrease of cloudiness, warming 
with falling air pressure and increase of cloudiness. Frequently, however, 
especially in the middle latitudes, a rise of pressure is observed with warm 
air invasions, and a fall of pressure with cold air invasions. This can only 
be explained by means of the overlying stratospherical waves. 
(4) Persistent obviously stratospherical high pressures and low pressures 
are sometimes observed. ‘These are circumscribed by short stratospherical 
waves, which can invite the building of cyclones. 
The stratosphere therefore controls }the tropospherical cyclones. 
‘Fronts ’ are stimulated when energy is supplied to them through altera- 
tions of the pressure gradient, which are determined in the stratosphere. 
On the other hand, however, a reaction of the occurrences in the tropo- 
sphere on the stratosphere also takes place. ‘This must be explained on 
purely dynamical lines, whereas the action of the stratosphere is purely 
statical. "There exists, therefore, a mutual coupling between stratosphere 
and troposphere. The Norwegian and German-Austrian cyclone theories 
are united in a ‘ theory of the complex cyclone,’ whose further investigation 
constitutes the chief problem of synoptical meteorology. 
Prof. E. REGENER.—New results in cosmic ray measurements (11.25). 
Mr. Wm. Tay tor, O.B.E., and Mr. H. W. Lee.—The development of 
photographic lenses at Leicester (11.50). 
The problem of the photographic lens is to secure a well-defined image 
over a considerable flat field. The solution was not discovered till dense 
barium crown and light flint glasses were available to the lens designer, 
although the principles applied by Dennis Taylor in the Cooke lens could 
have provided a solution with the older glasses. Rudolph (1890), Goerz 
(Dec. 1892), and H. Dennis Taylor (Jan. 1893) solved the problem, in 
different ways, with the aid of these. The Continental type of lens, 
