156 Things not generally Known. 



up by the atmosphere, and flow in invisible streams back 

 through the air to their sources among the hills ; and through 

 channels so regular, certain, and well denned, that the quan- 

 tity thus conveyed one year with the other is nearly the same : 

 for that is the quantity which we see running down to the 

 ocean through these rivers ; and the quantity discharged an- 

 nually by each river is, as far as we can judge, nearly a con- 

 stant. Maury. 



AN INCH OF BAIN ON THE ATLANTIC. 



Lieutenant Maury thus computes the effect of a single Inch 

 of Rain falling upon the Atlantic Ocean. The Atlantic includes 

 an area of twenty-five millions of square miles. Suppose an 

 inch of rain to fall upon only one-fifth of this vast expanse. It 

 would weigh, says our author, three hundred and sixty thou- 

 sand millions of tons : and the salt which, as water, it held in 

 solution in the sea, and which, when that water was taken up 

 as vapour, was left behind to disturb equilibrium, weighed six- 

 teen millions more of tons, or nearly twice as much as all the 

 ships in the world could carry at a cargo each. It might fall 

 in an hour, or it might fall in a day ; but, occupy what time it 

 might hi falling, this rain is calculated to exert so much force 

 which is inconceivably great in disturbing the equilibrium 

 of the ocean. If all the water discharged by the Mississippi 

 river during the year were taken up in one mighty measure, 

 and cast into the ocean at one effort, it would not make a 

 greater disturbance in the equilibrium of the sea than would 

 the fall of rain supposed. And yet so gentle are the opera- 

 tions of nature, that movements so vast are unperceived. 



THE EQUATOEIAL CLOUD-RING. 



In crossing the Equatorial Doldrums, the voyager passes a 

 ring of clouds that encircles the earth, and is stretched around 

 our planet to regulate the quantity of precipitation in the rain- 

 belt beneath it ; to preserve the due quantum of heat on the 

 face of the earth ; to adjust the winds ; and send out for dis- 

 tribution to the four corners vapours in proper quantities, to 

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

 sunshine, cloud, and moisture. Like the balance-wheel of a 

 well-constructed chronometer, this cloud-ring affords the grand 

 atmospherical machine the most exquisitely arranged self-com- 

 pensation. Nature herself has hung a thermometer under this 

 cloud-belt that is more perfect than any that man can con- 

 struct, and its indications are not to be mistaken. Maury. 



is another of these calm places. Besides being a region of 



