Equatorial dials

Sundial Park Jantar Mantar, Jaipur (India)

This is the large equatorial dial of Jaipur, the Samrat Jantar or 'magical instrument', which was the largest sundial in the world for many years. It is 27 m (90 ft) high; the time scales at both sides have a radius of 15 m (50 ft). The reading accuracy is claimed to be an unbelievable 2 seconds! That corresponds with 2 mm on the time scale.
The domed platform on top was used as a weather observatory.

Next to this giant a choice of other astronomical instruments can be found, all of sizeable proportions. I like the disk-shaped equatorial dial in particular. Its diameter is 3 m (10 ft) and its faces are divided over opposite sides of a small building.

Websites:

• The Indian Jiva Institute is devoted to the Vedic culture, which is the root of Hinduism and therefore forms the background of the Jantar Mantar. Plan and description of the instruments.
• The site of M. Audejean is quite extensive (also French).
• The page of Charles Hartley, of the Ernest B. Wright Observatory (Hartwick College, Oneonta, NY, USA) gives gnomonic and general information.
• Nikolaus von Bomhard also has an extensive site about the Jantar Mantar. In addition, information on coordinate systems etc. is given (also German).
• Great Buildings Online has a page with data, some pictures and a brief commentary.

Location: 26.9° N, 75.8° E
Design: Maharajah Jai Singh
Inauguration: 1734