Homemade sextants

The Astrolabe

The Sun Shadow Board

The Latitude Hook

The Kamai

The Quadrant

The Cross Staff

The Back Staff

You must be able to measure angles. Hands and fingers (see Figure 13.1) are one answer. Normally the angle subtended by a finger at an arm's length is taken as one degree but it varies from person to person. The Chinese called this measurement a chih and there were 224 chihs (1 chih = 1.6°) in a circle. Arabs called it an issabah. Nature places a limit on the size of angle you can measure au naturel. Unless you have abnormally large hands it is around 30-40°.

A word of warning: people go blind staring into the sun. Unless you use a shadow astrolabe or a sun shadow board, or have some very good shades, stick to stars, however tempting it is to take a sun sight.

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