Page:Popular Science Monthly Volume 89.djvu/143

 Fopul^r Science Monthly

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��Fig. 25

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��it looks like '-"ig. 25. Opened out flat, it appears as shown in Fig. 26.

Now if we fold this on line X and connect point? K by a brace exactly as long as one side of the triangle, we have a tetrahedral cell. Tie a bridle to it as shown. This kite has small surface for its weight, but it can be expanded by adding cells until it will carr>- almost an\- reasonable weight.

A large and complex tetrahedral is shown at the top of this page. Each cross represents one of the elements shown above, but now the frame work is composed of horizontal bars only. The trans\"erse bars are shown be- tween the rows of cells, and are so marked. The longi- tudinal bars are shown by the circles. 0\er this frame when tied together, \- e r 3- fine wires are stretched at the tetrahedral angle, and the cell surfaces are cemented to these. ,' The surfaces in the kite here shown ma>- be made of verj- Chinese rice paper. With the vertical supports shown, this makes a ver\- light and rigid flying-frame. It is a good plan to start with a few cells and gradually increase the number as you build successive frames and be- come more expert. The cells can be arranged in any regular or fantastic

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��figure as long as they are symmetrical about the keel.

The other 5 sticks should be of the same length, but made of stout bamboo, split about 5< in. wide. Whittle them till they balance nicely when hung inverted from the bottom stick. N'o other way of fastening can be used except lashing the intersections with fine copper wire or strong cord ; braided fish line is good. Make it measure 3 ft. exactly. Ever>' angle in the frame will now be exacth' 60 degrees. Di%"ide each stick into 3 equal parts, each one foot long. Take some fine copper wire (No. 28), and stretch it smooth between these di%ision points. When it crosses, tie it with sewing silk or cotton thread lashing. This ^*-ill make 9 di\isions on any face. Set it so you look along the bottom stick, and cover e\"er\- alter- nate triangle of wire that shows edge on to the front look at it in this position.

��Fig. 29

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with strong paper pasted on the wire. Tissue paper is good if strong enough to stand the strain. You should now have ten httle paper V'§, 3 on the bottom row, i behind the other, 4 in the center rows two and two, and 3 on the top, side by side. Looking down on the late, it looks like Fig. 28.

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