aquaria: their present, past, and future. 
259 
and it was a mere matter of course to connect the aquarium 
with this engine, and allow the water (which chanced to be 
drawn from a pure source) to run through the fish tanks, and 
then be applied to ordinary purposes, drinking or other, for 
which its passage through the tanks in no way unfitted it. I 
reasoned with the society that if the sea-water tanks were simi- 
larly treated on some such system as the fresh-water series, a 
correspondingly good result would be attained ; and I pointed 
out that the same law governed both, because in the centre of 
the building were some isolated fresh-water tanks having no 
stream in them, and these were in a similarly ill condition as 
the marine tanks by their side. In reply, the society answered 
that a circulatory system did exist in a part of the sea-water 
series, but that it was almost useless ; and I then pointed out 
that that was because the reservoir into which the sea-water 
entered after it had run through the show-tanks was too small 
in relation to the dimensions of the latter, and that the reser- 
voir should be several times greater than the show-tanks. My 
reasoning was all in vain, however, for the society went on 
throwing away the sea-water when it was only temporarily un- 
fitted for use, and getting at a cost of several hundreds of 
pounds yearly a weekly supply from the sea, especially when 
soon afterwards another evil made its appearance, consisting of 
a greenish-brown dense opacity permeating the water, and quite 
hiding from view all it contained. This was caused by excess 
of light, for I found that darkness removed it and made the 
water clear again ; and this led to Mr. E. Edwards’s invention 
of the dark-chambered tank, a modification of which is now, 
or should be, employed in all public aquaria where adequate 
results are aimed at and attained. So, at this early period, 
1853-62, though in theory the Zoological Society of London, 
and everyone else who maintained aquaria, used the same un- 
changed water, especially sea-water, yet most persons sent to 
the sea, or to dealers, of which I was then one, for occasional 
new supplies. However, from 1853 to 1855, when I could not 
possibly get new sea-water for my little jars, I merely increased 
the quantity of water to about eight or ten times as much as 
those jars collectively held. Thus the aggregate contents of my 
jars were about six or eight pints; and in a now historical earthen- 
ware foot-pan, kept dark in a cool corner at hand, I had five or six 
gallons more water, containing neither animals nor plants, and 
when aught occurred to disturb the equilibrium of life in these 
jars, either from excess of light or heat by standing on a light 
window-sill, or from excess of food, or from there being too many 
animals in a small space, instead of throwing away tne water thus 
temporarily rendered unfit to sustain life, I merely restored it to 
a right condition by pouring the contents of these jars into the 
