The protractor has a graduated disk, and is adjustable so it can be disposed at any angle.
All special tools of this kind are serviceable, and the boy should understand their uses, even though he is not able for the time being to acquire them. To learn how they are applied in daily use is an education in itself.
Utilizing Bevel Protractor.—Examine the full-page illustration ([Fig. 14]), and see how the bevel protractor is utilized to measure the angles of work, whether it is tapering heads or different kinds of nuts, or end and side surfacing, and it will teach an important lesson.
Truing Grindstones.—Devices for truing up grindstones are now made, and the illustration ([Fig. 15]) shows a very efficient machine for this purpose. It can be applied instantly to the face[p. 23] of the stone, and it works automatically, without interfering with the use of the stone.