Mercury (metal)

''This article refers to the metal. For the planet please see Saumya''

Mercury, or quicksilver, the room-temperature liquid metal element, is mentioned by several early Indian astronomers as use in automation. The first, is as part of a timekeeping mechanism. The second is in reference to construction of an automatically moving armillary sphere apparatus, a simulacrum of the moving planets and heavens.

Models of motion

The Sūrya Siddhānta mentions the armillary sphere use of mercury briefly, declining to describe it, and saying "let the supreme sphere be constructed only according to the instruction of the guru".

Āryabhaṭa describes an auto-rotating model vaguely in, saying the sphere "should be made to rotate. . . with the help of mercury, oil, and water, by the applications of one's own intellect"

Lalla echoes Āryabhaṭas comments in. He alo gives more detail: the 'basic principle' is that a "[weight floating for a day in mercury, oil, or water, rotates it with the help of the fluids]". . He describes a method where a gourd filled with mercury is floated in a cylinder of water; as the water drops the gourd pulls a string, which moves the Bhagola of the model.

Lalla has another description, saying a wheel of wood of the Śrīparṇi tree, "half-filled with mercury in its ... spokes, rotates by itself" He also uses the word bījas apparently to refer to mercury, oil, or water. .

Sūryadeva-yajvan in his commentary on describes a specific instrument, involving a gourd filled with mercury being placed inside a column of water, and attached to a string which will rotate the apparatus, 'keeping pace with time'

Timekeeping

Āryabhaṭa's describes a certain time-keeping instrument using mercury. A gourd is filled with mercury and put into a column of water while attached to a string. As the water drops out, the string pulls on a needle which indicates the time elapsed.

Lalla also describes the mercury-gourd-string method of timekeeping.