through the cone-shaped piece of spool. The hole through the can must be located in the exact center, so the top will balance properly. To find the center, place the box bottom down upon a piece of paper, and with a pencil draw a line around it. Cut the paper along the center, and you will have a piece the shape and size of the can bottom. Fold the piece in half, then in half again the other way (Fig. 127), open it up, and the intersection of the two folds, indicated by dotted lines in Fig. 128, will be the exact center. With the center located, place the piece of paper first upon the bottom, then upon the top of the can, and punch a hole through the center of it and the can, with the point of a large nail. Increase the size of the hole enough to admit the pencil.
Fig. 129.—A Spinning Top Race-Track.
Spin this top in the manner shown in Fig. 125. Hold the upper part of the pencil between your hands, with the palms together, and slide your hands back and forth, first
