EIGHTH ANNUAL MEETING. 49 
voirs represent the sea, the pump is the sun, the pipes are the 
clouds which convey the water where it is required, the spigots 
represent the rain, and the overflow-pipes are the brooks and 
rivers, which return the water to its starting place. And as fish 
only need water to keep them moist, and their gills free to 
absorb the oxygen contained in the water, therefore what they 
require is water supplied with fresh oxygen, which is fresh 
water. 
With these explanations I will now give my idea of con- 
structing an aquarium upon a new plan, the advantage of which 
is its economy. First, I would aerate the water by flowing over 
a shallow bed between the tanks, and then introduce it into 
the bottoms of them, that is, in at the bottom and out at the top, 
then over another wide, shallow space, and down an aperture 
to the bottom of the next tank. It takes but the slightest con- 
tact with the atmosphere for water to absorb its fill of oxygen, 
if spread out and exposed ; a flow of a foot in length by three 
feet in width, with a depth of half an inch, would be all suffi- 
cient. , 
The object of this is economy of water, hence economy of 
motive-power, and was suggested while studying the working of 
Williamson's “double riffle” hatching-trough. 
In all aquaria, as at present arranged, there are small pipes 
supplying each tank, and the tanks flow into each other, the 
second one getting all that flowed into the first, in addition to 
its own stream ; while the tenth in addition to being furnished 
with as much new water as the first one received, gets all that 
has passed through the other nine. It is evident that if the 
water is properly aerated after leaving tank No. 1, it is as good 
as new for the next one, and so on, making a saving in a row 
of ten tanks of nine-tenths of the water, and consequently 
of the power required to raise it. Second, The aquarium at 
Southport, England, has an elevated reservoir, into which the 
water is pumped from the lower ones and then flows into a few 
of the show-tanks, and the curator, Mr. Long, remarked that if 
it was large enough to contain a supply for a week it could be 
filled in one day, and then the engine might rest. 
Combining this idea with the former one there, seems to be 
