THE BO&TESMAN FILTER. 353 



Bosjesman women when procuring water for the use of their 

 families. When, as often happens, the only water to be obtained 

 is to be found in muddy pools which have been trampled and 

 perturbed by thirsty animals, the women have recourse to a 

 simple, though rather repulsive, expedient. 



Each woman is furnished with empty ostrich egg-shells by 

 way of water-vessels, and she also takes a couple of hollow 

 reeds. Over the end of one of these reeds she ties a bundle of 

 grass, and then plunges it as deeply as she can into the mud. 

 After a little while she sucks up the water through the tube, 

 the grass acting as a filter, and she then discharges it by the 

 second tube into the egg-shells. In this way the women will 

 obtain water, where none but themselves could have procured it. 

 As to the repulsive mode of obtaining it, no one can be fastidious 

 when dying of thirst. Sir S. Baker mentions that when he was 

 on his travels he managed in a halt to save up enough water 

 for a bath for himself and his wife. He was about to throw away 

 the soapy water, when the vessel was snatched from his hands 

 by two of his attendants, and the contents eagerly drunk. 



The different varieties of the Filter which we use at the pre- 

 sent day are too familiar to need description. Whether they 

 be made principally of charcoal, which is a powerful disinfect- 

 ant, or of merely stones, gravel, and sand, they are all con- 

 structed on the same principle, namely, the straining out solid 

 substances, and allowing only the pure water to pass through 

 the interstices. 



As to the Filters of Nature, they are almost innumerable. 

 In the first place, the Earth itself is the primary filter of all, 

 taking into itself all kinds of decomposing substances, separat- 

 ing them for the use of vegetation, and delivering the pure, 

 bright, and sparkling spring water which we so highly and 

 rightly value. The whole human body, again, is practically a 

 collection of. the most elaborate and effective filters that the 

 mind of man can conceive. But we will pass to the more 

 obvious examples of filters as seen in animal life. 



On the upper left-hand portion of the illustration may be 

 seen a long, fat, hairy creature, called popularly the Sea- 

 mouse, and known to zoologists as Aphrodite aculeata. 

 Although it inhabits the mud and sea-mud is about as 



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