Yol. 57.] CLIMATE OF THE PLEISTOCENE EPOCH. 469 



most that I can hope for is to have shown a jprima-facie case for 

 further investigation. My desire is to call the attention, especially 

 of meteorological experts, among whom I have no pretension to 

 rank, to a neglected, interesting, and possibly important branch of 

 enquiry.^ 



I desire especially to acknowledge my great indebtedness to 

 Mr. W. N. Shaw, F.R.S., who has not only permitted me to make 

 constant use of the valuable library at the Meteorological Office, 

 but has been kind enough to discuss the subject with me on more 

 than one occasion, and to give me the benefit of his experience and 

 of some important suggestions ; and also to Dr. A. Buchan, F.E,.S., 

 and Mr. J. G. Bartholomew, P.E..S.E., for their courtesy in allowing 

 me to copy maps from the 'Atlas of Meteorology.' My best thanks 

 are due, moreover, to Mr. H. N. Dickson, P.R.S.E., from whom 

 I have received some friendly and valuable criticism, and to 

 Prof. James Geikie, P. U.S., and others from whose writings I 

 have largely borrowed. 



X. SUMMAEY. 



The winds are an important factor in determining the distribution 

 of climatic zones. Deviations of the monthly or yearly isotherms 

 from the normal are coincident generally with the direction of the 

 prevalent winds. 



The influence of marine currents upon climate is indirect rather 

 than direct. Winds and currents, however, act and react on each 

 other. 



Changes of wind cause marked and sudden changes in the 

 weather : daily, as in Great Britain, or seasonally, as in India ; 

 though the general direction of oceanic currents remains more or 

 less the same. Permanent alterations in climate would also have 

 resulted during past epochs, had the course of the prevalent winds 

 been permanently changed. 



The winds blow in a direction more or less parallel to the isobars ; 

 the latter group themselves round centres of high and low pressure, 

 the higher pressure being, in the Northern Hemisphere, to the right 

 of a man standing wath his back to the wind. 



Anomalous weather is due to some unusual arrangement of the 

 areas of high and low barometric pressure. Similarly, former cases 

 of anomalous climate can only have occurred when the meteoro- 

 logical conditions were favourable. 



At present, the continental areas are hotter than the ocean 

 during summer, and are therefore cyclonic ; they are colder in 

 winter, and are then anticyclonic. Cyclones and anticyclones are 

 necessarily mutually complementary, as are the troughs and crests 

 of waves. The baric conditions of the oceans at ditfercnt seasons 



^ Among the services which palaeometeorology may hereafter render to the 

 geologist, not the least perhaps may be that of assisting him to determine the 

 chronological relations of geological zones in different regions where no direct 

 evidence bearing on the subject may be attainable. 



