DISTRIBUTION OF RAINS. |27 



the process goes on slowly, and a small amount of vapor only is 

 thrown into the air. From the surface of water at an elevated 

 temperature, the process goes on rapidly, and consequently large 

 quantities of vapor are thus precipitated into the atmosphere. 

 The vapor which rises from water at a temperature of 212°, ex- 

 pands nOO times ; that is, it occupies a bulk 1700 times as great 

 as the water from which it has been produced, while vapor from 

 water at 40° expands to occupy a bulk 3000 times as great as the 

 water from which it has generated. The altitude which vapor 

 seeks in the atmosphere depends upon the temperature of the sur- 

 face from which it has been generated. Vapor from water at 212° 

 is capable of ascending to an elevation of about three miles, while 

 vapor from water at 40° is capable of ascending to the height of 

 five miles before coming into a stratum of air of corresponding 

 density with itself. The vapor which rises at higher or lower 

 temperatures will seek relatively higher or lower elevations, so 

 that clouds are formed at all altitudes, from tlie surface of the 

 earth to the height of seven or eight miles, this latter elevation 

 being the height of the highest cirrus clouds. 



There is nothing, ladies and gentlemen, that comes down from 

 the clouds in the form of snow or rain, which has not first been 

 carried up to the clouds in the form of vapor ; consequently, the 

 measure of the quantity of vapor that annually rises from the sur- 

 face of the earth is, approximately, the measure of the rainfall for 

 the globe during the year. The quantity of vapor that rises from 

 the torrid zone, that highly heated belt 55° in width passing 

 around the globe, is sufficient to cover that entire zone to the 

 depth of nine and a half feet. The amount from the oceanic parts 

 of the torrid zone is sufficient to cover the area from which it has 

 risen to the depth of fifteen feet — so much greater is the quantity 

 of vapor produced from water surfaces than the amount from land 

 surfaces. 



The quantitj^ of vapor that rises from the temperate zones is 

 estimated to be about three feet, and the amount from the frigid 

 zones about two inches annually. The total weight of vapor 

 which annually rises from the earth, as estimated by Mr. Wells of 

 our own State, is in round numbers, sixty-five trillions of tons. To 

 accomplish the work of raising this vast quantity of vapor to the 

 clouds requires an expenditure of power equivalent to that of three 

 trillions of horse-powers, working ten hours a day ; and yet, this 

 enormous quantity is raised to the clouds by a process so noise- 



