NATURE'S REALM. 71 
twelve inches. On this is placed a row of 
seven-inch cylindrical glasses of clear flint 
glass, and in the centre, behind the jars, stands 
a twelve-inch, bell-glass aquarium, to be stocked 
with choice fishes or superfluous cabinet speci- 
mens. The first shelf has a breadth of eight 
inches to receive a row of six-inch glasses ; the 
second shelf a breadth of five inches, and the 
jars upon it measure four inches in diameter. 
The top shelf is only three and a half inches 
wide, and the glasses measure three inches 
across the top. The entire frame work has a 
breadth of about thirty-two inches, and a 
height, from the floor of the room to the level 
of the top shelf, of about sixty-six inches. 
The breadth and height of the window in 
which the cabinet is to be placed must have the 
first consideration with any one who may in- 
tend to construct such a piece of furniture ; the 
respective sizes of the vessels must be an after 
consideration, because, unless the whole be so 
adapted as that it shall enjoy a full share ot 
uninterrupted daylight, very little progress can 
be effected, especially if the growth of the more 
delicate forms of aquatic vegetation be at- 
tempted. 
In the absence of a properly constructed set 
of shelves, a few plain ones may be fitted up in 
a window. A single strip of deal, on brackets, 
would afford room for a dozen jars, and in 
these, by judicious groupings, specimens of 
from fifty to a hundred kinds could be kept, 
whether for observation by the naked eye or 
the microscope. 
Our jars are now stocked with minute 
aquatic plants, beetles of several species, diving 
spiders, water worms and mites, larva of 
beetles and flies, tadpoles in progress of trans- 
formation, mollusks of choice kinds and spawn 
of all kinds, removed from the tanks. Species 
that do not agree may be introduced to the 
bell glass, for the sake of teaching us the nature 
and incidents of the strife maintained in the 
great world out of doors; the battle may there 
have its way, and we may study destruction 
with as much profit as we may the momentary 
creation, by which the system of Nature is 
maintained in its completeness. In fact, the 
bell glass is a reservoir into which we may dip 
for almost anything we want to fill up vacan- 
cies in the jars, and to which we may consign 
the superfluities of a day's collecting, having 
first assorted and set apart such as are wanted 
for separate observation and study. 
AQUARIA GLASSES TURNING GREEN. 
Do you know of any preventive against the glasses turning 
green with a slimy substance if the water is not changed for 
some weeks. I have a good deal of trouble, and it is about the 
most disagreeable thing in keeping an aquarium arranged 
nicely. Foi. ka 
Your aquarium gets evidently too much light. 
Move it about twelve inches back from the 
window, toward the room, and let no sun shine 
against the glass. Once or twice a week wipe 
the inside of the glass with a small rough 
sponge tied to a stick. 
AQUARIUM TROUBLES. 
I herewith send another sketch showing location of my aqua- 
rium, and I will also give a further account of my management 
of it as well as can. As I wrote in my previous letter, my 
aquarium is about 40 inches long, 16 inches deep and 18 
inches wide. I have in the bottom cleanly washed sand and 
very small pebbles; in a common earthen flower jar, com- 
- pletely submerged in the water, a calla; no earth in the jar, 
nothing but fine sand. I also have a little moss, the variety ot 
which you may be able to recognize from sample enclosed. 
Since I received your letter I have added some larger pebbles, 
as you intimated they were necessary. I have forty or fifty 
fish, mostly goldfish, averaging about four inches long. Ot 
the native fish I have one-half dozen catfish about one inch 
long ; the balance of my natives are small common brook fish. 
The water keeps a kind of green color and frequently smells 
badly. It hardly ever, if at all, looks, or has, a milky color. 
I guess my feeding is wrong, tor / feed them very seldom in 
winter, only about twice a week, and this winter I have fed 
them nothing but raw beef scraped fine from a large piece ; but 
I have always been careful to give them just what they would 
eatandno more. However, I gave them prepared fish food last 
winter and I had the same bad luck about keeping the water 
clear. Almost every day toward evening the fish begin to 
come to the surface of the water, but in the morning they will 
be at the bottom swimming about feeding and apparently en- 
joying themselves very much. The four sides of my aquarium 
are glass. Should I clean out the aquarium when the water 
is in its present condition, or should I take out and throw away 
the water and sand pebbles and repiace everything new? 
And should I let the new water stand some time before return- 
ing the fish? 
I trust that with your information I may yet succeed with my 
aquarium. 1 an Ai i 
The capacity of your aquarium is about 
forty-five gallons. You have, in our judg- 
ment, about forty gallons of water in it. For 
the number of fish that you keep this is an in- 

