t or so long and open at both ends. The inside should be painted
black to prevent cross reflection of light. A square of clear glass
should be fitted into one end and puttied tight to keep out the water.
To use the water telescope, we simply shove the glass end under water
and look into the box. A cloth hood or eye piece to keep out the
outside light will make it more effective. The best way to use a water
telescope is to lie in the bottom of a boat which is drifting about,
and to look through the telescope over the side. As you study the
marvellous animal and plant life that passes along under you like a
panorama, see to it that in your excitement you do not fall overboard
as a boy friend of mine once did.

The care of an aquarium is a never ending source of interest to the
nature student. If a boy is handy with tools he can build one himself.
It is by no means an easy task however to make a satisfactory
water-tight box with glass sides, and my advice is not to attempt it.
Glass aquaria may be bought so cheaply that it is doubtful if you can
save any money by making one at home. If you care to try it, this is
the way it is usually done:

Use a piece of seasoned white wood 1-1/4 inches thick for the bottom.
If you wish your aquarium to be, say, 16 inches wide and 30 inches
long, this bottom board should be 20 x 34 to give a margin at the
edge. The size of a home-made aquarium can be anything that you
desire. It is customary to allow a gallon of water to each three-inch
gold fish that will inhabit it. By multiplying the three dimensions,
length, width and height of your box and by dividing your result,
which will be in cubic inches, by 231 (the number of cubic inches in a
gallon) you can tell how many gallons of water it will hold. Of course
the rule for gold fish is not absolute. The nature student will
probably have no gold fish at all. They are not nearly so interesting
as our native kinds. Besides nearly all varieties of fresh water fish
will either kill gold fish or if they are too large to kill will at
least make life so miserable for them that to keep them together is
cruelty to animals. If we keep in our aquarium the specimens that we
collect in our neighbourhood, beetles, newts, crawfish, snails, and
tiny sunfish the number may be greatly increased. Overcrowding however
is very bad. The ideal we should strive for is not "how many
specimens" but "how many kinds" we can have in our collection.

The white wood b