Page:Popular Science Monthly Volume 41.djvu/656

 mind, and it is essential to determine in what measure each appears in the general result.

If you hold out your arm nearly on a level with the shoulders and in line with them, you perceive at once that movements of the hand to the front are much more readily made than to the rear, and movements toward the body more readily than those away from the body; the tendency of the hand is to move along a circle of which the shoulder is the center. What we require is a position in which movements in any direction are as readily made as in any other; and this may be approximated, though only approximated, by holding the hand at an angle of about 45° with the line joining the shoulders, and with the elbow bent at an angle of about 120°; this position is



recommended for the normal tests. The usual result is a movement toward the object of attention; but when that is to the rear, this tendency is sometimes outweighed by the natural tendency