AND THE PREVAILING WINDS OVER THE GLOBE. 599 



Further, the Table of Winds shows a total absence of westerly winds on the north 

 coast of South America, the winds there being almost always from N.E. to E. or 

 occasionally S.E. ; whereas, at Bermuda, the winds, while mostly S. W., are more 

 distributed over the other points of the compass. The daily pressures charted 

 in Leverrier's "Atlas des Mouvements Generaux de 1' Atmosphere," give a ready 

 explanation of the winds of these two regions — pressures in the one case being 

 comparatively steady, whilst in the other they are fluctuating. 



3. Since winds bring with them the temperature and vapour of the regions they 

 have traversed, it follows that the data mapped on the Charts may be considered 

 as furnishing the key to the climates of the different parts of the globe, since the 

 approximate temperature and rainfall of the different seasons may thereby be 

 known. Between the monthly isobars and the rainy seasons of portions of Asia, 

 Africa, America, and Australia, there is an obvious connection. The distribution of 

 the pressure also explains the greater rainfall which occurs in Russia and other 

 places in the interior of Europe in summer, as compared with the other seasons. 

 For, if the winds of July in Table II. be compared with those in January at British, 

 French. German, Russian, and other European stations, they will be found 

 uniformly to show a shifting of the prevailing winds farther to the west and 

 north, — a change, doubtless, arising from the low pressures in Asia in summer. 

 The effect of this is, to draw over these parts of Europe, during the summer 

 months, air-currents more directly from the ocean than in the other seasons, from 

 which result a larger rainfall and greater fertility to these regions. 



The political importance even of such information will be seen when it is con- 

 sidered, that if there had been two or more years' Meteorological Observations, 

 especially of atmospheric pressure and winds, at Aden, Massuah, and Suez, at the 

 beginning of the Abyssinian war, the time of the commencement of the rainy 

 season in Abyssinia could have been stated. 



The Charts of monthly isobars, the monthly isothermals, and the information 

 tabulated in Table II., furnish materials from which more exact information 

 regarding the climate of a particular place may be obtained. Thus, suppose it 

 were required to know something of the climate of Shanghai, China. The mean 

 temperature in January is about 40°, being nearly that of the west coast of 

 Scotland ; the isobaric lines show an increase of pressure from Shanghai in the 

 direction of the interior of the continent; the winds for January are these: — 



Days each wind ha S prevail } J « £ - J »• J » »„ 



(January) at Shanghai, J 



Thus the mean direction of the wind is nearly N.N.W.; and, since this wind 

 comes from the continent, it may be concluded that it is dry, and, consequently, 

 that very low temperatures are of certain occurrence. Again, since in nine days 

 winds blow from N.E., E., S.E., and S., or from the ocean, and these winds, especially 



VOL. XXV. PART II. • 7 



