158 R. Mountford Deeley — Cyclones and Climate. 



Stenotheca abrupta, S. & F. (?). x 3. (See p. 156.) 



28 [3]. a, internal cast; b, outline of aperture. 



29 [5]. Internal cast. 



Coleoloicles typicalis, Walcott, var. multistriata, nov. x 2. (See p. 154.) 



30 [38]. Two specimens, showing slight taper. 



31. Type for var. [38]. a, exterior ; b, character of sculpture, x 6. 



32 [30]. A very minute tube, x 2. 



Fordilla troyensis, Barrande (?). x 3. (Seep. 156.) 



33 [15]. Exfoliated exterior. 



Platyceras primcEvum, Billings (?). x 4. (See p. 155.) 



34 [37]. Internal cast. 



II. — Cyclones and Climate. 

 By B. Mountford Deeley, M.I.C.E., F.G.S. 



f^ROM time to time I have been given an opportunity to discuss in 

 the Geological Magazine the question of the cause or causes of 

 climatic variations. The subject is one of deep interest to the 

 geologist. Even Lyell, in the first edition of his Principles of 

 Geology, gave a good deal of space to it, but contented himself with 

 merely pointing out that variations in the distribution of the land 

 would lead to changes in the climate. He wisely limited himself to 

 this aspect of the question, for, at-that time, the directions of the 

 winds in middle latitudes were not such as meteorological theory 

 would have led us to expect. 



The view was held in Lyell's time that the winds were the result 

 of the varying temperature of the air from place to place. The centre 

 of a cyclone came to be considered as consisting of a column of warm air 

 with cooler surroundings. The central warm air rose, became chilled 

 by expansion, and threw down its moisture in the form of clouds, 

 rain, hail, snow, etc. But the two great permanent cyclones of the 

 earth lay over or in the neighbourhood of the two poles of cold, just 

 where it seemed impossible, or very unlikely indeed, that a warm 

 column could exist. This was the great "stumbling-block" to all 

 progress. Indeed, it was held by many that, as further information 

 of the climatic conditions of the polar areas was obtained, it would 

 be found that there were really polar anticyclones within the polar 

 cyclones. But the barometric pressures found within the Arctic 

 Sea, and at the most southerly portion of the lioss Antarctic Barrier, 

 show that such polar anticyclones do not exist, and the strength and 

 constancy of the "brave south-westerly winds" of the southern 

 oceans continued to be one of the greatest of scientific puzzles. 



At the end of the nineteenth century meteorologists began to turn 

 their attention to the study of the conditions obtaining in the upper 

 air. Small balloons, having attached to them self-registering 

 thermometers and barometers, were sent up to sound the atmosphere, 

 and very unexpected results were obtained. It was found that up 

 to a variable height of about ten kilometres the temperature gradually 



