WATER IN AGRICULTURE. 175 



and the supply will prove abundant for all ordinary- 

 wants. This form of filtration will continue in 

 action for years. I have spoken of the device for a 

 twofold purpose : first, to call attention to a most 

 excellent and convenient way of filtering cistern 

 water, and second, to illustrate the method of ac- 

 tion of the ordinary drain tiles. The water passes 

 through the pores in the tiles, and drops are con- 

 stantly falling from the top arch and passing up 

 from the bottom, through the whole length of the 

 tubes, while resting in wet soils. The minute 

 orifices do not become obstructed as we naturally 

 suppose they would. I have known a brick filter- 

 ing chamber to supply pure water copiously for a 

 period of fifteen years, and doubtless they will con- 

 tinue in satisfactory action for fifty years. 



There is a property in water which is of the 

 highest importance, as upon it all success in agricul- 

 ture depends. I allude to its solvent power, or its 

 capacity of taking up and holding in solution every 

 substance which enters into the constitution of 

 plants. This singular property is, as it were, the 

 pivot upon which the existence and welfare of 

 the race are poised. Take away from water this 

 power, and no greater disaster could result if the 

 dynamical forces of the universe were thrown into 

 disorder, and the centripetal and centrifugal motions 

 should cease altogether. The rain which falls upon 



