FILTERS. 53 



These blocks will get clogged sooner or later 

 )ns ' and the frequency of cleaning them depends upon 

 the nature of the water filtered, some waters clogging the carbon 

 sooner than others. They are, however, easily cleaned by simply 

 washing them in hot water, brushing them with a soft brush, 

 and, finally, blowing through them two or three times, to open 

 the pores. When cleaned, they are equal to new, as only the 

 surface gets clogged. When the operation of filtering is over, 

 the ball should be blown through, to clear the pores from the 

 impurities, and put away in the case as dry as possible. 



When cattle have to be watered from a well, 

 or from holes dug in the sandy bed of a river, 

 which is often the case in African travelling, 

 having to bale out the water is an intolerable 

 nuisance. I therefore devised the following 

 arrangement, which Mr. Atkins, of 62, Fleet 

 Street, has carried out most effectually. 



Into the well or pool I drop a filter, which is 

 kept a foot or more below the surface by a float ; 

 to this is connected a tube or suction hose at- 

 tached to a small portable force pump, by 

 which I draw the pure water from the well, 

 and force it into a trough from which the cattle 

 drink. 



By this system the water in the pool remains 



