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190 length to line 1–2 of Fig. 271. With point 1 as a center and a radius equal to the hypotenuse of triangle 1–A, an arc is drawn below line 1–2. This is intersected by an arc drawn from point 2 with a radius equal to the hypotenuse of triangle 2–A. The intersection locates the point A on the pattern. With point 2 as a center and a radius equal to the hypotenuse of triangle 2–B, an arc is drawn bearing away from point A. This arc is intersected by another drawn from point A, whose radius is equal to line AB of Fig. 271. This intersection is lettered B. In like manner, points C and D are located. Then with point D as a center and a radius equal to the hypotenuse of triangle D–3, an arc is drawn bearing away from point 2. This arc is intersected by another drawn from point 2, whose radius is equal to line 2–3 of Fig. 271. Straight and curved lines connecting these points give the outline of the quarter pattern. This is now duplicated on the other side of line 1–A to obtain the half pattern.

Half-inch locks are added to each side of the pattern, but the workman, in forming the locks, should turn but in. It is advisable to construct a model from the plan and diagram of triangles, in order to aid in the visualization of the project.