Page:Popular Science Monthly Volume 92.djvu/310

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��Popular Science Monthly

��be substituted for the lamp oil, if a bulb IS placed in the jar.

The other methods of heating the aquarium differ from those just described in that a lamp is placed beneath the tank, which must stand upon a platform or frame- work of artistically designed ironwork. But only those aquariums may be so heated which are either built entirely of glass or those which have zinc bottoms. Both are placed in pairs with their refuse corners facing each other. Those made entirely of glass receive an extra piece of copper placed about an eighth of an inch from the glass bottom which the flame must strike. Aquariums with sheet metal bottoms do not need this extra piece of copper, when this method of heating is used.

Two other ways in which the aquarium may be heated, remain to be explained. Both work on the principle of water cir- culation. This method produces the best results, for none of the heat is wasted. One of the tanks receives a small box-like insertion, made of sheet zinc, which should cover the bottom of the tank. Two tubes, one shorter than the other, are soldered to the top of the box. The tank may then be arranged like an or- dinary aquarium so that only these tubes, covered with fine wire netting, project out of the sand. The water, in the box immediately below the soil of the aqua- rium, is heated with a small lamp. The water, as soon as it becomes warm, rises through the long tube, while the shorter one lets the cold water sink into the box. In this way, a continuous circulation is kept up. Another advantage of the box is that it does not heat the soil of the aquarium, which would materially injure the plants.

The other and last method is similar to the preceding one. Instead of the box, a U-shaped piece of tubing is soldered to the bottom of the aquarium. The curve, which projects about an inch below the aquarium, is heated. All beatable aquariums should be covered with a piece of glass when heated, unless a glass jar is used. Then the i)rotecting glass cover should have a large opening, corresponding to that of the jar, and it should be so situated that the heated air may escape and a fresh cool supply reach the flame. — Dr. E. Bade.

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��A Secure Fastening for an A-Shaped Sign

1UNCH room and other sidewalk signs -/ in the shape of the letter A will not stay in place on a windy day. Devices which might hold them steady are usually inconvenient to pedestrians. But with the fastening shown in the illustration, the holding device at the base of the sign may be set below the surface of the walk, where it will be in no one's way. When the turnbuckle is tightened, the sign cannot be blown away. The eye

may be on a stake driven into the earth where sidewalks are placed on the ground, or where a sign is used outside of the walk; but in the case of a cement walk, the eye may be set in the gravel or grout when the walk is laid. The holding de- vice may consist of a chain or of a rod with an ordinary turnbuckle in its center. The chain or rod is attached under and at the top of the boards and has a hook at the lower end for making connection with the eye in the walk. — G. P. Lehmann.

���Bolt with turnbuckle fastened in sidewalk

��Using Shingles to Make a Thatch- Like Effect at Eaves

PROBABLY every artistic soul has longed for a little home with droopy roof lines that stoop to meet the climbing ivy on the walls. You can go a long way toward get- ting it by making a bouquet of your shingles. Bore a hole through the first bunched line of shingles ex- tending over the eave, and wire them in place. Of

course it is necessary to slope the rafter ends and to put on the first sheathing board at a slope which will take the bunched shingles.— W. B. Smith.

���Shingles bunched to make the thatch effect

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