Hinduism,Cosmos ,Sanatan Dharma.Ancient Hinduism science.
The Samrat yantra or the ‘Supreme Instrument’ is Jai Singh’s most important creation. The instrument is basically an equinoctial sundial, which had been in use in one form or the other for hundreds of years in different parts of the world. In India, Brahmagupta (AD 598) describes Kartari yantra, an equinoctial sundial, which operates on the same principle as the Samrat. Jai Singh however, turned the simple equinoctial sundial into a tool of great precision for measuring time and the coordinates of a celestial object.
The Jantar Mantar was the largest of the five Astronomical Observatories built by Jai Singh. The Samrat Yantra is the world’s largest sundial, standing 27 meters (73 feet) high.The Samrat Yantra, pictured far right and in illustrations, below, is the largest sundial in the world. It’s gnomon rises over 73 feet above its base, and the marble faced quadrants, 9 feet in width, create an arc that reaches 45 feet in height.The primary object of a Samrat is to indicate the apparent solar time or local time of a place. On a clear day, as the sun journeys from east to west, the shadow of the Samrat gnomon sweeps the quadrant scales below from one end to the other. At a given moment, the time is indicated by the shadow’s edge on a quadrant.
The Jaipur observatory is the largest and best preserved of these. It has been inscribed on the World Heritage List as “an expression of the astronomical skills and cosmological concepts of the court of a scholarly prince at the end of the Mughal period”
The above One shows the principle of a Samrat yantra.
The instrument consists of a meridian wall ABC, in the shape of a right triangle, with its hypotenuse or the gnomon CA pointing toward the north celestial pole and its base BC horizontal along a north-south line. The angle ACB between the hypotenuse and the base equals the latitude lambda of the place. Projecting upward from a point S near the base of the triangle, are two quadrants SQ1 and SQ2 of radius DS. These quadrants are in a plane parallel to the equatorial plane. The center of the two ‘quadrant arcs’ lies at point D on the hyptenuse. The length and radius of the quadrants are such that, if put together, they would form a semicircle in the plane of the equator.
The tangential scale over Samrat gnomon. The scale indicates angle of declination.
To measure the declination of the sun with a Samrat, the observer moves a rod over the gnomon surface AC up or down until the rod’s shadow falls on a quadrant scale below. The location of the rod on the gnomon scale then gives the declination of the sun. Declination measurements of a star or a planet require the collaboration of two observers. One observer stays near the quadrants below and, sighting the star through a sighting device, guides the assistant, who moves a rod up or down along the gnomon scale. The assistant does this until the vantage point V on a quadrant edge below, the gnomon edge above where the rod is placed, and the star – all three – are in one line. The location of the rod on the gnomon scale then indicates the declination of the star.