जलयन्त्राणि — Water Devices: Fountains and the Dhārāgṛha

The longest single section of chapter 31 of the Samarāṅgaṇasūtradhāra is devoted to water. Bhoja first classifies water-machines by the way they move water: by falling, by rising to an equal height, by falling and rising again, and by lifting (31.109–116). He then describes the royal water-pavilions built on these principles (31.117–172): the dhārāgṛha, a pavilion of jets and streams; the pravarṣaṇa, which "rains" from figures of clouds; the praṇāla, in which water pours from the mouths, eyes and ears of carved figures; and the jalamagna, a chamber surrounded by water and entered by an underground passage. This article presents the classification and the key verses of the pavilions, and reads them in modern terms. The four classes correspond to gravity flow, the principle of communicating vessels (water finds its own level), the fountain driven by a head of water, and water-lifting. Bhoja's instruction that the supply pipe be two or three times the height of the device (31.119) is a rule for providing sufficient pressure head. His water-drinking elephant (31.115) has a direct parallel in the drinking animals of Hero of Alexandria. The pavilions are among the most detailed descriptions of hydraulic architecture in medieval literature, and all of them are technically feasible. Article 6 of the series Yantravidhāna Studies (SSD-31), on chapter 31 of Bhoja's Samarāṅgaṇasūtradhāra. Verses discussed: 31.109–172. Web version: sanskritmanthan.in/a/ssd-31-06-jala-yantra