Surface Details

One of the compelling aspects of the Jantar Mantar instruments are the inscribed surfaces from which the instruments derive their extreme precision. In the years since their construction, The observatories have suffered the damaging effects of weather, vandalism, and even warfare, and as a result each has at one time or another undergone a restoration. The first restorations were in Delhi and Jaipur in 1852 and 1876 respectively. Major restorations of the four extant observatories occurred between 1901 and 1923 under the direction of Gokul Chand Bhavan. During these restorations, changes were introduced. For example, the Western system of hours, minutes, and seconds replaced the Hindu system of time measurement on some of the instrument scales. The beautiful marble surfaces at Jaipur were added in 1945 to replace the deteriorating plaster scales of the 1901 restoration.

Samrat Yantra Scale

Determining time on the quadrant of the Great Samrat Yantra at the Jaipur observatory. The thin twig casts a shadow within the penumbra of the large shadow from the gnomon. As the twig is moved from side to side, there is a point at which its shadow suddenly disappears. This indicates the precise center of the larger shadow, enabling a high degree of precision. The scale is marked with divisions for (beginning at the top) hours, minutes, 6 seconds, and 2 seconds.

Jaipur Jai Prakash - upper area of scales
Jaipur Jai Prakash - crosswire shadow
Jaipur Jai Prakash - scale at bottom showing the zenith point
Jaipur Jai Prakash - center of polar coordinate system
Delhi Jai Prakash - scale along edge of rim
Delhi Misra Yantra - marble scale with divisions for hours, minutes, 6 seconds, and 2 seconds
Delhi Misra Yantra - quadrant
Delhi Rama Yantra - detail of central column
Delhi Rama Yantra - horizontal sector
Jaipur Samrat Yantra - quadrant with divisions for hours, minutes, 6 seconds, and 2 seconds
Ujjain Samrat Yantra - quadrant with divisions for hour, 15 minute, 5 minute, one minute, and 20 seconds
Varanasi Samrat Yantra - quadrant with divisions for hour, half hour, fifteen minutes, 5 minutes, one minute, and 15 seconds