Heritage week is celebrated
throughout world to conserve and appreciate ones history and culture. The
department of Archives, archeology and
museums is also celebrating heritage week from 19-25 November by public display
of rare manuscripts and medieval astronomical instruments like astrolabe and
celestial globe. There are four astrolabes and one celestial globe on display
in SPS museum during heritage week. Three of
the astrolabes have Sanskrit inscriptions and the only Indo- Persian astrolabe is most elaborate. It is
crafted by Ḍiyā al-Dīn Muḥammad of
prolific Allahdad family of Lahore in the year 1666 CE. All Sanskrit Astrolabes
have been crafted by another prolific metallurgist Lala Bullohmal Lahori
although they are not signed by him. The only celestial globe on display has
also been crafted by Lala Bullohmal
Lahori. All these instruments have been crafted of brass of various compositions.
The SPS museum possess few more traditional astronomical instrument like wooden
celestial globe, a metallic gazetteer and a
wooden mater of an astrolabe. There are no information about these
instruments in the museum such as from where and when they have been accessed.
However several International researchers have studied these or similar instruments
and catalogued few of them. Three of the instruments in SPS museum's collection
are unique and rare.
The astrolabe is an ancient
astronomical instrument/ analogue computer. Astrolabe is a very versatile instrument. It was first designed by Greeks to
measure the altitude of a heavenly body. It was used to ascertain position of
celestial bodies like Sun, Moon, planets and stars in the sky. It was also used
for measuring height and distances in land surveys. It can also be used to
simulate the motion of heavenly bodies at any locality and time. In fact it can
also be used to measure time. The design, manufacture and applications of
astrolabes were improved by Arabs in middle ages. It was used to calculate the
Qibla and to find the times for Salah.
Several types of astrolabes have
been made since antiquity. The most popular type is the planispheric astrolabe,
on which the celestial sphere is projected onto the plane of the equator. A
typical astrolabe was made of brass and was about 6-10 inches in diameter,
although much larger and smaller ones were also made. An astrolabe consists of
a disk, called the mater (mother), which is deep enough to hold one or more
flat plates called tympans, or climates. A tympan is made for a specific
latitude and is engraved with a stereographic projection of circles denoting
azimuth and altitude and representing the portion of the celestial sphere above
the local horizon. The rim of the mater is typically graduated into hours of
time, degrees of arc. Above the mater and tympan, the rete or ankabut, a
framework bearing a projection of the ecliptic plane and several pointers
indicating the positions of the brightest stars, is free to rotate. The rete,
representing the sky, functions as a star chart. When it is rotated, the stars
and the ecliptic move over the projection of the coordinates on the tympan. One
complete rotation corresponds to the passage of a day. On the back of the mater
there is often engraved a number of scales that are useful in the astrolabe's
various applications; these vary from designer to designer, but might include
curves for time conversions, a calendar for converting the day of the month to
the sun's position on the ecliptic, trigonometric scales, and a graduation of
360 degrees around the back edge. The alidade is attached to the back face.
When the astrolabe is held vertically, the alidade can be rotated and the Sun
or a star sighted along its length, so that its altitude in degrees can be read
from the graduated edge of the astrolabe. The concept of astrolabe was introduced
in India by noted polymath Alberuni through his writings. The medieval rulers
Firoz Shah Tughlaq and Humayun patronized astronomy. During Mughal period some
finest astrolabes were manufactured in Lahore. The Indo persian astrolabe in
SPS museum has been designed and crafted in Lahore. It consists of body with kursī shackle and ring, rete for 51 stars,
10 plates, alidade, pin and washer. There are ten plates serving the latitudes
11° to 45° at 2° intervals and the ecliptic coordinates and multiple horizons.
Of the three Sanskrit astrolabes in the possession of SPS museum one is
ordinary in the sense that similar astrolabe is extant in Rampur Raza library
also. The two astrolabes which have solid retes are unique. No such sample is
extant anywhere except SPS museum. Noted Scholar SR Sarma has attributed these
two to Lala Bulhomal Lahori.
A celestial globe is a three
dimensional model of the sky. It was mostly used for pedagogical purpose rather than an
observational instrument like astrolabe. The celestial globe has the advantage
of simplicity of design and the ability to function at any geographic location.
A hollow celestial globe can either be made in two hemispheres and joined or
they can be casted seamlessly in single piece using lost wax technique. The
earliest confirmed date for the manufacture of a seamless cast globe is 1589-90
CE, when a globe made by 'Ali Kashmirl ibn Luqman' was produced. The technology
of casting of seamless celestial globe
was transferred from Kashmir to Lahore and Allahdad family and Lala Bulhomal
also practiced the same technology. There are about 20 extant globes in the
world crafted using the technique of lost wax. Even present day copper
metallurgists of Kashmir use similar wax inside their copper bowls to provide rigidity
while carving designs.
There are no constellation
figures on the globe at SPS museum, the positions of some prominent stars like
Suhel are marked with inlaid silver nails. Unlike in other globes by Bulhomal,
there are no meridian circles here. The globe is mounted on a three-legged
stand. The stand consists of an ornate horizontal ring, a meridian ring and a
zenith ring without a crown. Both the horizontal and meridian rings are
graduated in 1° and 6° and labelled in Abjad notation. An axis passing through
the two celestial poles on the globe is pivoted to the meridian ring in the
stand. The curved legs are decorated with a leaf pattern.
SPS museum also possess a unique Safvid qibla indicator. On the two outer and the two inner side
of the qibla indicator, the geographic information is engraved in annular circles, carrying the names,
longitudes and latitudes of many localities arranged according 6, 12, 18, 24,
30 degree lattitudes, the numbers starting from the equator and reaching to the
tropics. There is an urgent
need to do a scientific study of all these astronomical instruments to know the
history of science in this region.
