406 MR. F. W. HAEMER ON THE [Aug. I9OI, 



The comparatively genial climate of Great Britain during the 

 winter is attributed to the Gulf Stream (using the term in its popular 

 sense), but the action of the latter is indirect rather than direct; 

 when the wind blows from the north-east, the influence which it 

 -exerts on our thermometers is practically nil. No one asks, when 

 the weather suddenly becomes colder, whether the Gulf Stream is 

 running in diminished volume, but whether the wind has not 

 changed. If winds from the north, or the east, were as prevalent 

 during winter as they are in spring, the yearly average tempe- 

 rature of these islands would be much lower than it is at present.^ 

 It is somewhat strange that, in their speculations as to the causes of 

 the anomalous climates of the past, and especially of those of the 

 Pleistocene Epoch, although geologists have fully recognized the 

 important part played by marine currents, as well as the influence 

 of winds upon the latter, they have seldom enquired how far climatic 

 disturbances may have been due to the variations of the winds 

 themselves.'^ Aerial currents may, however, in the course of a few 

 hours, wholly change the temporary climate of any district, by 

 bringing over it vast volumes of air from regions to the north, 

 or the south, as the case may be.^ Seasons, abnormally warm or 

 cold, rainy or dry, may be caused in like manner, though the course 

 of the oceanic circulation remain the same ; and permanent 

 alterations would equally result, were the direction of the prevalent 

 winds permanently changed. 



It may be profitable, therefore, to enquire whether any of the 

 cases of anomalous climate which obtained during the latest part 

 of the Tertiary Epoch may have been brought about in this way. 

 It will not be difficult to show that the meteorological conditions 

 of that epoch must have differed from those of our own times. 



If, by bringing the teachings of geology and meteorology together, 

 we can ascertain the prevalent direction of the winds in different 

 parts of the Northern Hemisphere during past ages, we may reach, 

 I believe, conclusions interesting to students of both sciences, which 

 may at the same time suggest a reasonable solution of some 

 geological difficulties. Abnormal conditions of climate in former 



' It is true that marine and aerial currents are closely connected, and that 

 they act and react on each other, often cumulatively ; the action of the latter 

 is, however, the more rapid and far-reaching of the two. 



2 In a paper published in 1869 (Tians. Eoy, Soc. Edin. vol. xxv, p. 592) 

 Dr. Buchan, while pointing out that temperature and rainfall are influenced by 

 the direction of the preA^ailing winds, suggested that alterations in the distri- 

 bution of land and water during past epochs would have reacted upon climate. 

 The view here taken, however, is that climatal changes may also have been 

 produced by variations in the relative position of areas of high and low 

 barometric pressure, even when, as in Pleistocene and prehistoric times, the 

 relation of the continental and oceanic areas to each other was more or less 

 similar to that of the present day. 



^ Mr. H. S. Eaton stated, in a Presidential address to the Meteorological 

 Society (Quart. Journ. Met. Soc. vol. iii, 1877, p. 316), that during the Siege of 

 Paris, a balloon travelled from that city to Norway, 1,000 miles in a direct 

 line, in 15 hours. 



