A FEW WORDS ABOUT OUR WATER SUPPLY. 



BY ARTHUR HOLLICK. 



THE AVEEAGE annual rainfall on Staten Island, according to 

 I careful observations by Mr. Chas. Keutgen, during the ten yeara 

 from January 1st, 1870, to December 31st, 1880, was about 47 inches. 

 How many of our citizens understand fully what this means, or real- 

 ize the facts involved and their significance? We have become so 

 accustomed to our abundant water supply that its source is a matter 

 of indifference to most of us, and even its delivery, except when some 

 accident occurs, has become a matter of very vague interest. 



Suppose we examine the statement in regard to our rainfall and 

 see if it leads to matters having a claim upon our attention. It 

 means, in the first place, that if all the rain which fell on any level 

 portion of our Island during an average year could be retained there 

 —none being lost by evaporation into the atmosphere or by absorp- 

 tion into the earth — it would form a layer of water over that portion 

 of the Island almost four feet in depth. Now, one inch of rainfall 

 means about 100 tons of water to an acre of land, so that during the 

 average year each acre of our Island receives about 4,700 tons of 

 water. If we apply the old housewife's adage that "a pint of water 

 weighs a pound," we shall have 10,528,000 pounds or pints of water, 

 equal to 1,316,000 gallons per acre. It is not necessary here to cal- 

 culate and put into figures the amount that falls upon the entire 

 surface of the Island, but for the benefit of those who may wish to 

 do it I will state that the superficial area of Staten Island is about 

 fifty-nine square miles. 



The question naturally arises next, what becomes of all this im- 

 mense amount of water? It is disposed of in three different ways : 

 by surface drainage, by absorption into the earth and by evaporation. 

 Where the surface is hard or impermeable the bulk of the water will 

 run oft* at once in the form of streams. If the ground is soft or porous 

 a large part of the water will be absorbed, forming the source of 

 supply for springs and wells. The water carried off by evaporation 



