THE EQUATORIAL CLOUD-RING. 175 



feet, the philosopher thought, but was afraid to say, it was owing 

 to the " weight of the winds ;" and though the fact that the air 

 has weight is here so distinctly announced, philosophers never 

 knew it until w^ithin comparatively a recent period, and then it was 

 proclaimed by them as a great discovery. Nevertheless, the fact 

 was set forth as distinctly in the book of nature as it is in the book 

 of revelation ; for the infant, in availing itself of atmospherical 

 pressure to suck the milk from its mother's breast, unconsciously 

 proclaimed it. 



351. Both the thermometer and the barometer (^ 347) stand 

 lower under this cloud-ring than they do on either side of it. Af- 

 ter having crossed it, and referred to the log-book to refresh his 

 mind as to the observations there entered wdth regard to it, the at- 

 tentive navigator may perceive how this belt of clouds, by screen- 

 ing the parallels over w^hich he may have found it to hang from 

 the sun's rays, not only promotes the precipitation which takes 

 place within these parallels at certain periods, but how, also, the 

 rains are made to change the places upon which they are to fall ; 

 and how, by traveling with the calm belt of the equator up and 

 down the earth, this cloud-ring shifts the surface from which the 

 heating rays of the sun are to be excluded ; and how, by this op- 

 eration, tone is given to the atmospherical circulation of the world, 

 and vigor to its vegetation. 



Having traveled with the calm belt to the north or south, the 

 cloud-ring leaves the sky about the equator clear ; the rays of the 

 torrid sun pour down upon the crust of the earth there, and raise 

 its temperature to a scorching heat. The atmosphere dances 

 (§ 205-6), and the air is seen trembling in ascending and descend- 

 ing columns, with busy eagerness to conduct the heat off and de- 

 liver it to the regions aloft, where it is required to give momentum 

 to the air in its general channels of circulation. The dry season 

 continues ; the sun is vertical ; and finally the earth becomes 

 parched and dry; the heat accumulates faster than the air can 

 carry it away ; the plants begin to wither, and the animals to per- 

 ish. Then comes the mitigating cloud-ring. The burning rays 

 of the sun are intercepted by it. The place for the absorption 

 and reflection, and the delivery to the atmosphere of the solar 

 heat, is changed ; it is transferred from the upper surface of the 

 earth to the upper surface of the clouds. 



352. Radiation from the land and the sea below the cloud-belt 



