TROPICAL AQUARIUM FISHES 213 
when brought into contact with aquarium cement it absorbs and spreads 
the oil, making a bad appearance. Bases of heavy white pine, strongly 
cross-battened, have been used with success, but the wisdom of using a 
wooden base is open to serious question, especially as wide, thick pine 
boards can scarcely be had any more, even at high prices. The ever- 
present danger of warping either from a leak or the weather, or again 
from bending due to continuous heavy pressure are considerations weigh- 
ing against the wooden base. If an all-wood frame is used, it is desirable 
to line the bottom with a sheet of glass, preferably wired, embedding it 
in soft aquarium cement at the edges, and at several supporting spots 
near the centre. The same plan is to be recommended in aquaria with 
solid metal bases, in order to keep iron rust out of the water. 
Aquarium bases usually extend from one to one and one-half inches 
beyond the frames on all sides. Slate or marble bases ought to be bev- 
elled sufficiently on the upper edges and corners to take away the sharp- 
ness. The necessary holes through which the frame is to be clamped on 
can be drilled with an ordinary metal drill, but it costs very little extra 
to have the slate-worker do this when he is finishing the base. Aquaria 
up to 10 gallons require 4 bolts, 20 gallons 6, and for the larger sizes 
they should be placed about 10 inches apart. 
Frame Metals. Angle brass, iron or aluminum form the best metal 
aquarium frames. For the amateur worker, brass offers the best advan- 
tages. It is easily sawed, drilled and soldered, besides making a handsome 
appearance when polished and lacquered or nickel-plated. If nickeled it 
should be heavily coated. Angle iron is not so attractive in appearance, 
but is undoubtedly more rigid. It cannot be soldered. Consequently the 
four corners of the upper and lower frames have to be riveted through 
connecting elbow pieces on the inside or special castings on the outside, 
and then the whole riveted to the uprights. Aluminum has seldom been 
used, but makes an attractive frame. As the soldering of this metal is 
of doubtful durability it is safer to rivet the same as with iron. 
For aquaria up to 25 gallons, 54-inch angle metal is suitable; up 
to 50 gallons, 34 inch; up to 75 gallons, 1 inch; up to 125 gallons, 1% 
inch. The author prefers seeing as little of the frame as possible and 
for ten years has successfully used a 60-gallon aquarium constructed with 
only 5%-inch angle brass, but he would not care to make this as a general 
recommendation. It is mentioned so that if others have the same idea 
they will know that it is a mechanical possibility. 
Unless constructed of heavy angle iron it is best to carry a light rod 
across short dimension of the centre of top frame of aquaria over 30 
inches in length, to prevent bulging by water pressure. 
