Jacob’s staff
device · 1342 · Middle Ages
A navigational angle gauge.
Inventors: Яков бен-Махир ибн-Тиббон, Gersonides.
What it is made of
- Graduated wooden staff — has part. A long bar with a scale.
- Sliding transom — has part. A movable arm for measuring the angle.
Principles and materials it uses
- Wood — is made of. A Jacob’s staff is wooden.
- Trigonometry — uses. The altitude of a celestial body is found from an angle.
History: what it evolved from and what it influenced
- Davis quadrant — evolved into. Davis spared the navigator from looking at the Sun.
Things built in a similar way
- Quadrant — works like. Two angle gauges for measuring the altitude of celestial bodies.