Page:Popular Science Monthly Volume 91.djvu/318

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302

��Popular Science Monthly

��of triangles at an angle of 120 deg. The center row of triangles should be bent at an angle of 72 deg. The bending may be done by means of a "brake," or over a "hatchet stake" with a mallet.

The beginner, learning the trade, will be interested to know the scientific name for such a finial. In solid geometry it is one of a group of forms called "poly- hedrons," meaning many sided solids. The word "poly" means many. A cube is a polyhedron that has six equal faces and its special name is a "hexahedron." A solid with eight faces is an "octahedron." This finial, the pattern of which is de- veloped, is called an "icosahedron," because it has twenty faces.

��Folding Camp Fireplace Made of Angle Iron

ANY one who likes to go camping will l be interested in these stoves. The only tools needed to make them are a hacksaw, riveting hammer and a breast drill with a 3/16-in. bit. The sides are made of two pieces of angle iron % by Y% in. The ones used in making the fire- place illustrated were taken from an old bedstead. The legs are % by 3/16-in. flat iron and the bars across the top are from flat galvanized steel 1 by 3/16 in. This is used to hold the sheets of gal- vanized iron together. These sheets may be obtained at any tinsmith's shop at a small price. One advantage of this style

���a. A 6

��ANGLE IRON-

����LEGS FOLD UP WHEN NOT IN U5E

��The frame may be easily folded flat so that it can be put away in a narrow place

of grid or fireplace is that it folds up com- pactly and is steady when set up. It also has the great advantage of being adjust-

��able as to width. The fireplace folds into a narrower but longer space than when open. I have found it extremely useful as a stand for an ordinary camp stove when used in a tent; for when it is opened to its full extent it just fits a small iron stove. — B. E. Dobree.

��Garden Seat with Checkerboard in Its Top

GARDEN seats of the ordinary bench type can be made to serve a twofold duty by placing in the center of their upper surfaces a checkerboard design. In the

���The checkerboard on the garden seat makes checkers an inviting outdoor game

wood top, squares may be cut out with a chisel or knife and alternate ones painted black. The checkermen can be kept in a small drawer placed under the seat.

If a cement seat is made along these lines, black and white square tiles can be set in the cement to form the checkerboard design. In making the seat of cement, places must be provided for screws or ex- panding bolts which must be inserted on the underside at the center for holding the drawer slides. — Edward R. Smith.

��Constituency of Rubber for Side Walls of a Tire

THE side walls of a tire must be flexible in order to properly distribute the strains, give resiliency, minimize heat, prevent sharp bending of the fabric,, break- ing and separation. Therefore, it is desir- able that the rubber on side walls of a tire be elastic and not too dense or firm; the kind of hard wear resisting rubber used on the tread is not suitable for covering the side walls. The difference in materials and adaptability for tires may be compared with automobile and machinery parts- some materials are required to possess great strength and some are selected for other qualities, according to their tasks.

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