Post by Jinsei on Jun 26, 2007 22:02:14 GMT -5
THE 14th-century Pir Ghaib Observatory, nestled in the campus of Hindu Rao Hospital, appears at first to be just another of the ancient ruins scattered across Delhi but a closer examination shows the observatory to contain apparatus that is astonishingly modern in its technological understanding.
Newsline reported Nehru Planetarium's discovery of the monument, located in the Ridge, on May 14. And now, the monument built by Feroz Shah Tughlaq, has been found to contain two rooms, one of which has a hole in the ceiling extending through the roof and is supported by two arches that face the north and south.
This small hole, half a degree in size, confirms that the monument was once used as an observatory. The hole in the ceiling would have enabled observers to view the highest point in the sky (the zenith). The hole and its arches form an empty tube that points to the sky, called the "zenith tube".
This tube could have been used to observe all celestial objects that passed through the zenith of Delhi's skies. Although exact use of this tube is still a matter of research, the Nehru Planetarium here has narrowed in on two uses for the Pir Ghaib. Research reveals that the zenith tube was used for correcting clocks that operated on water as per 14th century practice.
Such clocks had simple methods of measuring time - for example, a drop in the level of water in the clock showed how much time had elapsed. Since this system was rudimentary, it was error-prone. To correct this, attendants at the observatory would observe the position of a particular star and correct the clock's time.
This could be done only if the attendants knew the exact time at which a particular star would appear at the sky's zenith.
Once they saw the star they would know the correct time and compare it with the time shown by the clock. Any difference would be corrected.
But this may not be the only use of the Pir Ghaib observatory. The diameter of the hole is about half a degree, which is the exact size the moon appears to be in the sky. Additionally, the moon passes through the zenith of Delhi's sky once every 18 years.
Anurag Garg of the Nehru Planetarium says: "The moon would appear to fit (into the hole)." Thus, the monument could also have been used to study the moon.
The most intriguing aspect of the tube is that it is supported by two arches that let fresh air into it. These arches would also enable hot air in the tube to escape.
Garg explains, "Cross ventilation in the zenith tube would allow the observer to see a larger number of stars."
The technology of building air inlets in the zenith tube is a recent phenomenon but the builders of Pir Ghaib may have had this expertise 700 years ago.
Newsline reported Nehru Planetarium's discovery of the monument, located in the Ridge, on May 14. And now, the monument built by Feroz Shah Tughlaq, has been found to contain two rooms, one of which has a hole in the ceiling extending through the roof and is supported by two arches that face the north and south.
This small hole, half a degree in size, confirms that the monument was once used as an observatory. The hole in the ceiling would have enabled observers to view the highest point in the sky (the zenith). The hole and its arches form an empty tube that points to the sky, called the "zenith tube".
This tube could have been used to observe all celestial objects that passed through the zenith of Delhi's skies. Although exact use of this tube is still a matter of research, the Nehru Planetarium here has narrowed in on two uses for the Pir Ghaib. Research reveals that the zenith tube was used for correcting clocks that operated on water as per 14th century practice.
Such clocks had simple methods of measuring time - for example, a drop in the level of water in the clock showed how much time had elapsed. Since this system was rudimentary, it was error-prone. To correct this, attendants at the observatory would observe the position of a particular star and correct the clock's time.
This could be done only if the attendants knew the exact time at which a particular star would appear at the sky's zenith.
Once they saw the star they would know the correct time and compare it with the time shown by the clock. Any difference would be corrected.
But this may not be the only use of the Pir Ghaib observatory. The diameter of the hole is about half a degree, which is the exact size the moon appears to be in the sky. Additionally, the moon passes through the zenith of Delhi's sky once every 18 years.
Anurag Garg of the Nehru Planetarium says: "The moon would appear to fit (into the hole)." Thus, the monument could also have been used to study the moon.
The most intriguing aspect of the tube is that it is supported by two arches that let fresh air into it. These arches would also enable hot air in the tube to escape.
Garg explains, "Cross ventilation in the zenith tube would allow the observer to see a larger number of stars."
The technology of building air inlets in the zenith tube is a recent phenomenon but the builders of Pir Ghaib may have had this expertise 700 years ago.