Page:Physical Geography of the Sea and its Meteorology.djvu/370

344 643. Difference in tons of the barometric pressure upon the north-east and south-east trade winds.—With those barometric observations, and the assumed fact that the mean pressure of the atmosphere is 15 lbs, upon the square inch, we may readily determine in tons the total by which the superincumbent pressure upon the south-east trade-winds between the parallels of 5°and 20° exceeds that upon the north-east between corresponding parallels. For the whole girdle of the earth, the excess of pressure upon the south-