| 
Short Papers and Notes. 145 
the grain running across that of the cedar. This combination is 
set on end, and will, according to the state of the weather, be 
found to have bent on one side or the other; this may be 
determined on trial. 
A davine Aquarium. 
For an aquarium, whether fresh-water or marine, a tank is 
better than a globe, because a larger surface of the water is exposed 
to the air, and the larger the surface of water exposed to the air the 
greater the quantity of oxygen absorbed from the atmosphere, and 
the better the health of the inhabitants of the vessel. 
A salt water aquarium does not require so much light asa 
fresh water, therefore give the glass a coat of green paint on all 
sides but one, which leave clear for the front. The rockery or 
arch in the centre, cement together with the following cement :— 
Take ten parts, by measure, litharge, ten parts plaster of Paris, 
ten parts dry white sand, one part finely powdered rosin, and mix 
them, when wanted, into a pretty stiff putty with boiled linseed oil; it 
will be ready for use in three days, and hardens under water. Put 
an inch of sand from the beach over the bottom of the aquarium. 
The water should be obtained from the ocean some distance from 
the shore. Choose such seaweed as you prefer, with the small 
stones attached, and the stones will sink, keeping the plants in an 
upright position. A window facing north or south is the best 
situation for a marine aquarium. Do not introduce the animals 
till the plants begin to thrive and put forth new shoots, and take 
care not to put in too many animals. If you do they will surely die, 
and there must be at all times pure air and perfect ventilation in 
the room, and there must be no smoking in the room, as the 
smoke will taint the air and thus the water. Keep a glass over 
the top of the aquarium to keep out the dust, but it must have 
standards half an inch long so that there may be a space for the 
free admission of fresh air. 
The water will slowly evaporate, but the salt will not, so you 
will only have to fill up the tank with water. July and August 
will be found the hardest months of the year to keep the water 
pure. Lean beef dried and cut fine may be used for feeding, or 
oysters or clams chopped fine, or the prepared food which is for 
sale. Keep the aquarium free from all dead animals, dead 
vegetation, or surplus food. 
When the water becomes foul a filter may be made of a flower 
pot. Leave a hole in the bottom large enough to insert a goose- 
quill, then fill the pot half-full, first of a layer of charcoal at the 
bottom, sand next, and gravel on the top. Hang this filter some 
distance above the aquarium, and let the water fall into it drop by 
drop. 
