4916 THE ZooLoGist—May, 1876. 
Maximum external air at Sydenham and Greenwich - 92° F. 
= air in shade in Crystal Palace’ - - BL ip 
7 air in shade in Crystal Palace Aquarium - 77 ,, 
5 in water in Crystal Palace Aquarium, every- 
where - - - - : - - ere (ai 
and J asked for similar information about the Manchester Aquarium, 
but it was refused me. Indeed, our great success at the Palace 
depends very much on our temperature being nearly that of the 
actual English ocean in all seasons; and it is this, conjoined with 
complete and constant aération by our machinery, that enables us 
to keep in a comparatively small space so many animals, and many 
of them of kinds which, when we once get them uninjured, are 
maintained nowhere else under the same inland conditions. Among 
these we kept some young herrings till they were eaten by a noc- 
turnally prowling eel. And we now keep Sepia (one of the cuttles), 
and it feeds and grows vigorously, as it feeds and grows in no other 
aquarium. 
Irrespectively of the consideration of temperature (which, how- 
ever, cannot be readily left out), and if, indeed, it be necessary to 
argue that a given amount of any diffusable matter sullies a given 
large body of fluid less than a small body, we possess a good 
illustration of the effect which great masses of water exert when 
brought into contact with smaller masses, containing much decom- 
posing organic matters, which the larger masses rapidly dilute by 
their bulk, and gradually resolve into their constituents, by referring 
to the improvements made of late years in the drainage system of 
London. Formerly the sewage matter resulting from a great mass 
of human beings and other animals was permitted to flow into the 
tidal river Thames, the bulk of which did not then allow it to 
become very seriously polluted. But as the metropolis rapidlly 
grew larger, and as the river did not so increase, the pollution 
of the stream increased in the same proportion, until at last the 
decomposing organic matters it contained, upon being washed up 
and down as it ebbed and flowed, before it ran into the sea, became 
so intolerable from the poisonous gases they evolved—especially in 
warm weather, when the decomposition was more rapid—that it 
was resolved to make the sewage flow more directly into that 
infinitely larger receptacle, the sea, which even the enormous mass 
of London sewage has no power to permanently and seriously 
affect. This brings me to explain why I chose the formula No. 6— 
