272 THE BRIP-GLASS. 



become chemically changed, and deprived of their 

 putrescent qualities. This is what takes place in 

 nature. By the perpetual dashing of the waves against 

 the shore, and especially against the ragged rocks, an 

 immense quantity of air becomes entangled, in the 

 form of minute bubbles, which by the various currents 

 are diffused through the sea, and even carried to con- 

 siderable depths, before they rise to the surface and 

 become dissipated. Thus the violent agitation of the 

 sea is a powerful agent in its purification. 



One of the simplest modes by which this object can 

 be effected, is the drip-glass. I have been accustomed 

 to suspend over the Aquarium, a perforated bell-glass 

 (T think it is called a bee-glass) of suitable size, into 

 the orifice of which a bit of sponge may be pushed, 

 or a cork drilled with small holes. The cord which 

 suspends the drip-glass passes over a pulley at the top 

 of the window, so as to be raised or lowered at plea- 

 sure. Every morning sufiBcient water from the Tank 

 is drawn or dipped off, to fill the drip-glass, which is 

 then hoisted to its full height. The contents run out 

 in slender streams, or in a rapid succession of drops, 

 which, passing through some four or five feet of 

 air before they reTach the Tank, become efiectually 

 purified. 



The same purpose may be more efficiently accom- 

 plished at a slight expense, in a manner which would 

 greatly augment the elegance of the Aquarium. In 

 the engraving placed at the commencement of this 

 chapter, I have represented a Fountain- Aquarium, a 

 form of the invention particularly suitable for a con- 

 servatory or hall. It needs but a vessel fixed, as a 



