The band and space enclosed is called a cell of the kite. So this kite has two cells. The length of the cell is the same as the width of the kite and is represented by _b_; the depth of the cell is the same as the height of the kite in its present position, and is shown by letter _e_; the breadth of the cell by letter _d_; and the distance between cells, _c_, is called the vent. Nearly all box-kites require the vent, and the vent is usually wider than the breadth of the cell. Usually the two cells, the fore and aft, are the same size, but not necessarily so. No one would be seen flying a box-kite with any kind of tail unless that had a purpose in carrying out the design. The square box-kite, Fig. 60, is square in cross-section, is very serviceable for flying, and is convenient for carrying. It is usually made to fold up, and the bridle is attached to one corner piece of the frame. This kite flies diagonally in the air. It is quite easy to attach the bridle to two corner sticks of the frame, when it flies horizontally, Fig. 61. Lining cambric is good for covering and some bright color should be used; but some prefer a good wrapping paper. Chinese tissue may be used if the kite is not too large. The corner sticks stand diagonally in the corners of the kite so that the notches of the braces can fit over them, see Fig. 62. The drawing represents the end of the kite, with the corner sticks stretched apart. Fig. 63 represents a part of one of the braces. String and glue are used back of the notch to prevent splitting when the strain is put on them up in the air. The braces are made just a little long so that they bow a little when in place, and this stretches the cover tight. [Illustration: FIGS. 64, 65, 66.]