Water instrument

Several instruments in Indian astronomy used water as the basis for their operation. For example:


 * āḍhaka (vessel of 50 palas)
 * clepsydra / ghaṭikā-yantra - measured the time of one ghaṭi (~1/60th day )

Water was also mentioned as a way of putting into motion an armillary sphere

Though not technically an instrument, water itself was used to level ground in preparation for the installation of astronomical insruments. See for example Lalla's, and his example of preparing a śaṅku (gnomon). Nīlakaṇṭha's Manusyālayacandrikā has a similar śaṅku description.