754 WINDSOFTHEGLOBE. 



A knowledge of the atmospheric pressure is of the greatest importance for the explanation of the 

 courses of the winds. The explanation of these maps is found in the "Discussion and Analysis of 

 Wlndc," where constant reference is made to it. 



PLATES 15 TO 20 Inclusive. 



Relative Prevalence of Winds, in Summer and Winter, expressed in Percentage. 



Plate 15. Arctic Regions. 



Plate 16. Europe, south of latitude 60°. 



Plate 17. Asia and Africa, between 25° and 60° north latitude. 



Plate 18. Tropical Regions, north of the equator. 



Plate 19. Tropical Regions, south of the equator. 



Plate 20. South Temperate Regions, between latitude 25° and 60° south. 



These six Plates represent tlie relative prevalence of winds from the different points of the compass 

 in summer and winter, taken as the most marked seasons, and are adapted to the ready comparison 

 and contrast of these seasons. The width of shading of the outer ring, reckoned from the circum- 

 ference toward the centre, expresses in hundredths of an inch the percentage given in the Tables for 

 the summer ; in like manner, the inner belt of shading is used for the winter. The distance of tiiese 

 pairs of limiting circumferences from each other is 30 per cent. ; when, therefore, the tabular per- 

 centage is in excess of this amount, the irregular contour line that marks the inner limit of the width 

 passes into tlie next inner space. 



Monsoon influences of marked character are vividly depicted in Plate IT (Hakodade, Nangasaki 

 and Pekin), Plate 18 (Celebes Sea and China Sea), and Plate 19 (Sween Island, Australia), the 

 belts of shading far outstripping their limits, and even overlapping one another in the cases of Port 

 Blair and Colombo, Ceylon. On the contrary, when the bands are symmetrical for the two seasons, 

 these windroses show the absence of any noticeable monsoon influence, as on Plate 16, for Europe, 

 in the cases of Dublin, Greenwich, St. Petersburg, Vladimir, Debreczin and Gorki; 



PLATE 2 1. 



Percentage of Winds for the Four Seasons. 



This Plate differs from the preceding only in containing windroses for spring and autumn, and 

 illustrates the general similarity of the former to winter and of the latter to summer. 



PLATE 2 2. 



Relative Prevalence of Winds in the United States, in Summer and Winter, expressed 



in Percentage. 

 [Illustrated by Vertical Projection.] 



This Plate, somewhat more compact in form, exhibits facts of the same nature as those contained 

 in Plates 15 to 20, the percentage of winds at any place being represented in horizontal widths 

 measured across the vertical bands. It enables one readily to find at what place wind from any 

 particular direction is prevalent, by simply tracing down the column until great breadth is reached. 



PLATE 2 3. 



Barometrical Windroses. 



This Plate was drawn by the author as an early attempt to illustrate the connection between the 

 rise and fall of the barometer and corresponding changes in the direction of the wind. The width 



