Mr White's Nero Method of Filterifig Water. 171 



account of the experiment, as tried at the house of the nobleman who was the 

 first to patronise tlie design. The figure, as shewn in the diagram, is a sec- 



ifi^**/^ 



tton through the centre of the machine, which shews the whole of its interior 

 construction. The cistern containing the water is not introduced, as its 

 height would exceed the limits of the diagram ; but let the small pipe P be 

 supposed to communicate with it, and be of any length, from 10 to 100 feet : 

 it is, however, necessary to bear in mind, that the quantity filtered will al- 

 ways be proportioned to the area of the stone multiplied into the height of 

 the column or pipe. The advantage, therefore, of employing a high cistern 

 to supply the machine, requires no other recommendation. 



Three years ago, in the south of Russia, in the government of Poltava, 

 when, on a mission appointed by the late Emperor to examine the mechanical 

 and agricultural state of that part of the Russian empire, it fell to my lot to 

 give a design for filtration on a large scale. To effect that object, T intro- 

 duced the water to be filtered below a bed of sand and gravel : it was intended 

 for the purpose of washing wool, consequently did not require that purity 

 IMToduced by this invention. But at the house of the nobleman I have al- 



