NATURAL HISTORY. 



CENTURY I. 



Experiments in consort, touching the straining and 

 passing of bodies one through another ; which they 

 call Percolation. 



DIG a pit upon the sea-shore, somewhat above the 

 high-water mark, and sink it as deep as the low- 

 water mark ; and as the tide cometh in, it will fill 

 with water, fresh and potable. This is commonly 

 practised upon the coast of Barbary, where other 

 fresh water is wanting. And CaBsar knew this well 

 when he was besieged in Alexandria : for by digging 

 of pits in the sea-shore, he did frustrate the laborious 

 works of the enemies, which had turned the sea- 

 water upon the wells of Alexandria ; and so saved 

 his army being then in desperation. But Caesar 

 mistook the cause, for he thought that all sea-sands 

 had natural springs of fresh water : but it is plain, 

 that it is the sea-water ; because the pit filleth 

 according to the measure of the tide ; and the sea- 

 water passing or straining through the sands, leaveth 

 the saltness. 



2. I remember to have read, that trial hath been 

 made of salt-water passed through earth, through 



VOL. IV. B 



