p 



f URIFICATION- O^ V/ATER. ' Q'J 



Defcription of the filtering Apparatus, Plate V. Fig. 1 . 

 A B The exterior tube, two feet high and fix inches fquare Filtering appa- 

 Within. . ratusdcfcribed. 



C D The interior tube, four inches fquare at the top and 

 three inches at the bottom. It reaches within about three 

 inches of the bottom of the exterior tube, and is covered at 

 the bottom with a coarfe h'nen tied round it. The ufe of this 

 i& to prevent the weight of the water from diflurbing the fand. 

 The upper end of this tube is formed into a funnel, for the 

 cpnvenience of filling it with water, and it refts on the outer 

 tube, E a fpout for the exit of the filtered water. 



Both tubes are filled with clean waihed fand up to the dot- 

 ted line juft below the fpout. A bag for flopping the coarfer 

 impurities may be adapted to the funnel. If this machine be 

 placed under the cock of any common water ciilern, which is 

 opened juft enough tofupply the funnel without running over, 

 it will require no attendance," and will very feldom want clean- 

 ing. It is obvious that every part of the machine, when the 

 two tubes are taken afunder is vifible to the eye, and eafily 

 reached by the band. The fand, when waftied, will ferve 

 jnany times. 



If inftead of a funnel, a larger refervoir of water at the tpp 

 is ufed, which may fometimes be convenient, it will be bed 

 to fill the upper part of the inner tube for a few inches with 

 clean fmall pebbles, as the pouring in water diliurbs the upper 

 lurface of the fand. 



It may be made either of wood or tin, but not of lead, for 

 fear of impregnation. It is alfo evident that the rapidity of 

 adion of the filtre will be in a great degree regulated by the 

 diflTerence of level between the fpout and the furface of the 

 water in the funnel, and by fupplying the funnel with a greater 

 or letfer flream, the machine may be made to a6l as quick or 

 as flow as is wiflied. 



As the water which fupplies the metropolis is often tainted Whether char- 



with vegetable or animal fubftances putrified in it, it might be *^°^^ ^^'^"^^ K 



,. , 1 ., . , /-iv I • 1-1 advantageous m 



well worth while to try whether tillmg the mner tube with a filtering appa- 



powdered charcoal might not tend to free the water filtred"*"*^^'^ ^**^* 



through it from the difagreeable tafte and fmell communicated 



by the caufes above-mentioned. It will alfo be advantageous 



to place the receiving vetTel at fome diftance belaw the fpout, 



that the flream may fall through as much air as it conveniently 



can. 



Vol. IX. — October, 180-i. H Experiments 



