Hindu ruler in centuries to perform the ancient Vedic ceremonies like the Ashwamedha (1716) sacrifices — and the Vajapeya (1734) on both occasions vast amounts were distributed in charity. Being initiated in the Nimbarka Sampradaya of the Vaishnava sect, he also promoted Sanskrit learning and initiated reforms in Hindu society like the abolition of Sati and curbing the wasteful expenditures in Rajput weddings. It was at Jai Singh's insistence that the hated jaziya tax, imposed on the Hindu population by Aurangzeb (1679), was finally abolished by the Emperor Muhammad Shah in 1720. In 1728 Jai Singh prevailed on him to also withdraw the pilgrimage tax on Hindus at Gaya. In 1719, he was witness to a noisy discussion in the court of Mughal Emperor Muhammad Shah. The heated debate regarded how to make astronomical calculations to determine an auspicious date when the emperor could start a journey. This discussion led Jai Singh to think that the nation needed to be educated on the subject of astronomy. His interest may have been kindled as early as 1702 by his tutor Jagannatha Samrat. Despite local wars, foreign invasions, and consequent turmoil, Jai Singh found time and energy to build astronomical observatories. Five observatories were built at Delhi, Mathura (in his Agra province), Benares, Ujjain (capital of his Malwa province), and his own capital of Jaipur. His astronomical observations were remarkably accurate. He drew up a set of tables, entitled Zij-i-Muhammadshahi, to enable people to make astronomical observations. He had Euclid's "Elements of Geometry" translated into Sanskrit as also several works on trigonometry, and Napier's work on the construction and use of logarithms. Relying primarily on Indian astronomy, these buildings were used to accurately predict eclipses and other astronomical events. The observational techniques and instruments used in his observatories were also superior to those used by the European Jesuit astronomers he invited to his observatories. Termed as the Jantar Mantar they consisted of the Ram Yantra (a cylindrical building with an open top and a pillar in its center), the Jai Prakash (a concave hemisphere), the Samrat Yantra (a huge equinoctial dial), the Digamsha Yantra (a pillar surrounded by two circular walls), and the Narivalaya Yantra (a cylindrical dial). The Samrat Yantra is a huge sundial. It can be used to estimate the local time, to locate the Pole Star, and to measure the declination of celestial objects. The Rama Yantra can be