272 PHYSICAL GEOGRAPHY OF THE SEA, AKD ITS METEOROLOGY. 



give vitality and power to the system are brought into play — where 

 dynamical strength is gathered, and an impulse given to the air 

 sufficient to send it thence through its long and tortuous channels 

 of circulation. 



522. Thus this ring, or band, or belt of clouds is stretched 

 It acts as a regulator, aromid OUT plauct to rcgulatc tlic quantity of pre- 

 cipitation in the rain-belt beneath it ; to preserve the due quan- 

 timi of heat on the face of the earth ; to adjust the winds ; and 

 send out for distribution to the four corners vapours in proper 

 quantities to make up to each river-basin, climate, and season its 

 quota of sunshine, cloud, and moistm'e. Like the balance-wheel of 

 an artificial machine, this cloud-ring affords the gTand atmospherical 

 macliine the most exquisitely-arranged seIf-com])ensatwn. If the 

 sun fail in his supply of heat to this region, more of its vapom's are 

 condensed, and heat is discharged from its latent store-houses in 

 quantities just sufficient to keep the machine in the most perfect 

 compensation. If, on the other hand, too much heat be found to 

 accompany the rays of the sun as they impinge upon the upper 

 circumference of this belt, then again on that side the means of 

 self-compensation are ready at hand : so much of the cloud-surface 

 CIS may be requisite is then resolved into invisible vapour — for of 

 in-vdsible vapom- are made the vessels wherein the sm-plus heat of the 

 sim is stored aw^ay and held in the latent state until it is called for, 

 when it is instantly set free, and becomes a palpable and an active 

 agent in the grand design. 



523. Evaporation under this cloud-ring is suspended almost 

 T]ted'in''the^p?o."^^" entirely. We know that the trade- wmds encircle the 

 j^^ses of condensa- earth ; that they blow perpetually ; that they come 

 the ci.;ud-ring, true froui the uorth and the south, and meet each other 

 ^vinds?^ ^^^ "^^^'' near the equator ; therefore we infer that this line of 

 meeting extends around the world. By the rainy seasons of the 

 torrid zone, except where it may be broken by the continents, w^e 

 can trace the declination of this cloud-ring, stretched like a girdle 

 about our planet, up and down the earth ; it travels after the sun 

 up and down the ocean, as from north to south and back. It is 

 broader than the belt of calms out of wliich it rises. As the air, 

 with its vapom's, rises up m this calm belt and ascends, these vapours 

 are condensed into clouds, and this condensation is followed by a 

 -turgid intumescence, w^hich causes the clouds to overflow the calm 

 belt, as it w^ere, both to the north and the south. The air floTNTUg 

 oft' in the same dii'ection assumes the character of T^inds that form 



