Beth Jacob, age 10, of Fostoria, Ohio, for her question:

Of what use is a sextant?

The sextant is not a gadget to tell whether an egg will hatch into a chicken or a rooster, and it cannot help the doctor predict whether an unborn baby will be a boy or a girl. The first syllable of the word means six, and the sextant instrument uses a metal curve which is one sixth of a circle. The arc is marked in degrees, and it works with two mirrors, a movable arm and small telescope.

The job of a sextant is to measure distance from angles. It is adjusted to fix on two distant points. As a rule, these two points are the sun and the horizon. Pilots of ships and planes use a sextant to find exactly where they are on the earth's surface by comparing their positions with objects in the sky.