I 31^ ] 



air, and that of the tropic to which the fun approaches, '* being 

 " rarefied by heat and preffed upon by the colder air, rifes and 

 " diftufes itfelf above, forming a current in a contrary direction 

 " to the fubjacent inferior current of the colder air; fo that a NE. 

 " wind below is attended with a SW. wind above, and a SE. 

 *' below with a NW. above." Here his flatement ends, but the 

 laft part of it is erroneous, or at leaft ambiguous ; for from it one- 

 would be apt to deduce the exillence of two fimultaneous fuperior 

 currents, one on the northern and the other on the fouthern fid; 

 of the Equator, whereas he mofl probably meant two fuccefTive 

 currents, as he tells us that it is the air of the tropic to which 

 the fun approaches that flows in a contrary diredion to the colder 

 air below ; now as the fun cannot at the fame time approach 

 both tropics, it follows that thefe currents, like the fun's ap- 

 proaches, mufl be fucceffive ; fo that when the fun is in, or ap- 

 proaches to the fouthern tropic, that is, during the winter of the 

 northern hemifphere, a SE. current prevails in the upper regions 

 of our hemifphere, and when the fun, during our fummer, ap- 

 proaches to, or is in the northern tropic, a NE. wind prevails in 

 the upper regions of the fouthern hemifphere ; and in fa(5l this 

 equatorial intumefcence muft neceffarily flow and diffufe itfelf in 

 that diredlion in which it meets with leafl refiftance, and it meets 

 with leaft refiftance in blowing towards that hemifphere in which 

 at equal heights the air is moft rarefied ; now w^hen the fun is in, 



or 



