Equatorial Armillaries
- Woodcut depicting an equatorial armillary.
- Tycho Brahe (1546-1601).
- Tychonis Brahe Astronomiae instauratae mechanica.
- Nuremberg: Levinus Hulsius, 1602.
Brahe also built equatorial armillaries to overcome the problem of the rings of the zodiacal spheres shifting under their own weight. Essentially, these armillaries were used to calculate the position of celestial bodies according to equatorial coordinates. One category of these armillaries, shown in this image, is labeled as Armillae Aequatoriae Maximae, sesquialtero circulo continentes (The Largest Equatorial Armillaries, comprising one and a half circles); its full circle was 2.6 m. in diameter, and it was installed in a self-centering axis.