Filtration of Water . 
Certificates. 
38 
W e, the undersigned^ having inspected and examined 
a new mode of employing the ordinary filtering- stone; 
discovered by William Moult; are of opinion that its su- 
periority over the customary method is so great as to en- 
title it to particular notice. 
That it not only supplies an infinitely greater quantity 
of purified and limpid water; but is capable of preserving 
its porosity free and pervious for years together; by an 
occasional self-operation. 
That by this valuable process the principal objections 
to drip-stones is removed; viz. the constant labour they 
require to keep them clean by means of brushes; without 
eventually producing the intended effect; and without 
preventing their being finally rendered useless. 
D’Arcy Preston; captain in the Royal Navy; 
Charles Gower; M. 3). $ 
Thomas Pitt; Esq. Y. P. Wimpole street ; 
Richard Davenport; Esq. Wimpole street. 
Reference to the Drawing of Mr, Moults Filtering 
•Apparatus, Fig. 1, PI. 2. 
A A is the cistern containing the water to be filtered ; 
the filtering stone B is suspended in the cistern by a ring 
around the inside of it; which catches the projecting part 
of the stone ; the water in the cistern filters through into 
the stone. D is a siphon; which conveys the filtered wa- 
ter from the inside of the stone into a cistern E; which 
the reservoir for clean water, d a cock to draw it off as 
it is wanted. By this mode of filtration the impurities of 
the water are deposited in the bottom of the cistern A; in- 
stead of being left in the bottom of the stone as in the usual 
mode. 
Ym,. m 
R 
