Davis quadrant
device · 1594 · Early modern era
An angle gauge that let the navigator avoid looking at the Sun.
Inventor: John Davis.
What it is made of
- Small arc scale — has part. A scale for large angles.
- Large arc scale — has part. A scale for small angles.
- Shadow vane — has part. It casts the Sun’s shadow onto the slit.
Principles and materials it uses
- Wood — is made of. The Davis quadrant is wooden.
- Trigonometry — uses. The Sun’s altitude is found from the angle of a shadow.
History: what it evolved from and what it influenced
- Jacob’s staff — evolved from. Davis spared the navigator from looking at the Sun.
- Octant — evolved into. Reflecting angle gauges.