Armillary sphere

was an instrument used in Indian astronomy.

Lalla wrote of it's importance, pointing out that the mean motion of planets was easily visible on it.

wrote on the Armillary sphere his. He described in great detail it's general arrangement. He started with the viṣuvad circles (3 main great circles), namely the

He mentioned svastika - 4 crosses made by the equinoctial colure with the other viṣuvads, at the 'cardinal points'.

Next he described the Apama-vṛtta (ecliptic), ahorātra-vṛtta (diurnal circles), orbits of the planets, the pāta (lunar nodes), and finally the Nakṣatragola / Bhagola (Starry sphere), the Khagola (Celestial sphere, outside of the starry sphere), the clay Earth, another circle (Unmaṇḍala) to hold it all, and spacers (śara-daṇḍikā).

Lalla
Lalla, in, describes an armillary with 51 great cirlces representing the objects of the heavens.

Each of the 7 planets gets a set of the following:


 * epicycle
 * eccentric
 * dṛṅmaṇḍala
 * dṛkkṣepamaṇḍala
 * apamaṇḍala / kakṣāmaṇḍala

Each of the 5 star-planets gets:


 * śīghra epicycle
 * śīghra eccentrics
 * vimaṇḍala (plus one more for the moon)

The Bhagola, sphere of stars, is inside the Khagola, or celestial sphere. The latter can be mounted on four pillars, while the Bhagola can be rotated by ropes, etc.

For more detail, please see the article on Lalla.

Sūrya Siddhānta
Also mentioned:
 * The Seven Sages (saptarṣayas) of Agastya, Brahmā, etc.
 * Waterflow
 * quicksilver

Automatic armillary spheres
The Sūrya Siddhānta describes an automatically moving armillary sphere, involving quicksilver (mercury), water, and oil. It declines to give a description. Āryabhaṭa, Lalla, and others give similar and (usually vague) descriptions of automatic armillary sphere devices.

These may be amongst the earliest analog computers, comparable with the Antikythera Mechanism, Zhang Heng and his water-powered armillary sphere, Al-Jazari and astronomical clocks, etc. Please see the article on mercury (metal) for more information.