Page:An introduction to linear drawing.djvu/42

 ﻿(20)

H (21)

After having marked two points, trace an arc of a circle which shall pass through both of them. The centre must be somewhere on a perpendicular to the middle of a cord which would join these two points.

35. Make several arcs pass through two given points•

Draw one arc as in problem 34, then a cord from point to point, then a perpendicular to the cord, and then you may make any number of arcs pass through the two points, all of whose centres must be on the per- pendicular.

This problem will assist the pupil in drawing the me- ridians on a map of the globe.

36. Describe a circle, and circumscribe it with a hexagon. (fig. 22.)

Cut the circumference into six equal arcs, as if you wished to inscribe the hexagon. Then draw a radius to each point, and six tangents perpendicular to the tangents may be drawn as in fig. 22, where they meet and form an angle on the prolonged radii.
 * radii will form the regular hexagon required. Or, the

(fig. 21.)

(22)