equinox: see equinoxes.
The green patination found on weathered brass and copper.
A small moveable scale for obtaining fractional parts of the subdivisions of a fixed scale. Invented by Pierre Vernier in 1631 (published Brussels, 1638). For circular scales, a Type A vernier has a central zero. After about 1780, sextants commonly had a Type B vernier with the zero on the right of the scale. European instruments often have the very similar nonius.
See principal plane.
Tides etc. A ~ has sometimes been included around the rod-gnomon of equiangular dials.