A MARINE AQUARIUM. 5 
the stop-cock destroying the vacuum, the outflow instantly ceases; and 
the jet-pipe in due course refills it. 
5 &—The Warning-pipe. In pumping, the Cistern which we are fill- 
ing is out of sight in the roof above. In order to know when it is full, 
that we may not allow it to overflow, a small pipe is inserted into the 
side of the Cistern, an inch below the brim; which, leading down 
through the ceiling, ends at a few inches over the surface of the Tank. 
This is in sight of the person who is pumping, who cannot help hearing 
the babble of the stream, and seeing its sparkle, as it comes suddenly 
pouring down the warning-pipe; and he makes not a single stroke more. 
These were, I think, all the essentials to the working of the scheme ; 
but one or two additions were subsequently made, which I will describe. 
The jet thimbles could never be removed or replaced, without causing 
an annoying splash of water all around one’s person and the furniture. 
To obviate this I had a vulcanite stop-cock inserted into the jet pipe, 
just above the jet. ThusI could close the pipe, before I unscrewed the 
jet; and I had now no more splashing. I have found this stop-cock 
useful in another way. When I siphon-off the water with the object of 
getting rid of the impalpable organic mud and humus, which commonly 
accumulates on the bottom, I remove the jet, and allow the jet-pipe to 
pour down its vertical torrent in full force. Thus all the moveable 
matters held in suspension, are whirled about; and very many of them 
are carried, in the siphon, down the waste-pipe to the Reservoir; where 
they settle quietly on the bottom, the organic parts dissolve, and the in- 
organic slowly accumulate in a thin pellicle on the bottom, requiring to 
be cleaned out, perhaps in a dozen years hence. 
Although the sea-water originally put into the Reservoir was 
brilliantly clear and pure, and the wooden lid was made to fit close, we 
yet thought it prudent to guard against the possibility of extraneous 
matters being drawn into the supply-pipe, during the pumping, and so 
choking it. Accordingly a tight bell-shaped box of vulcanite was made 
to screw on to the bottom of the supply-pipe, about 6in. from the floor 
of the Reservoir. The bottom and sides of this box were drilled with 
many 4in. holes; so that it serves as a strainer, like that at the bottom 
of the waste-pipe. 
The pipes were all made in lengths, with the requisite angles and 
connections ; and were sent from London, carefully numbered, according 
to copious working-drawings. No bend can in the least degree be changed, 
vulcanite being inflexible and brittle. Every piece was fitted and screwed 
to its fellow, and ‘‘payed” with red-lead; some of the joints being also 
“served” with muslin. The lengths beneath the surface of the yard 
were carefully rammed with earth; and those which passed up the house- 
wall were secured to the joist by semi-circles of iron; and then inclosed 
in a narrow box of board, for facility of examination in case of need. 
The new window sash was now hung on hinges from the upper frame, 
and opened outward, to different degrees, by graduated metal quadrants, 
above the Tank ; the area, much wider than originally, was made a bay- 
form recess, which allowed of a little useful angle on each side of the 
Tank. The pump, the pipes, the slate of the tank, were all painted 
