This photograph shows the Samrat Yantra, a giant sundial, at the Jaipur Observatory in India. It is one of a series of massive instruments built and designed under the supervision of Maharajah Jai Singh II (1686-1743). Finding European, Islamic and Hindu astronomical tables inaccurate, Singh decided to make his own observations to improve matters. As ruler of Rajastan he built several observatories, starting in 1724 with one near Delhi. Built of masonry, the Jaipur instruments were used to accurately measure the position of the Sun, stars, moon and planets. These devices were without telescopes and relied upon naked eyesight and massive, but precise construction.
© Science Museum / Science & Society Picture Library