Slide #214.3
TITLE: Sketch map of the Distribution of Land
and Sea
DATE: 1029 A.D.
AUTHOR: Abu al-Rayhan Muhammad ibn Ahmad al-Biruni
DESCRIPTION: Al-Biruni worked during the first half of the 11th century
A.D., first in his native Khwarazm under the patronage of the last of the
local rulers. In 1017, on the conquest of Khwarazm by the Ghaznavid ruler
Mahmud, al-Biruni was carried off to Ghazna almost as part of the booty.
Under Mas'ud I (reigned 1030-40), the son and successor of Mahmud, al-Biruni
was able to go on with his writing and scientific work. It was here about
1036 that he completed his great astronomical work Kitab al-qanun al-Mas'udi
fi al-hay'ah wa-al-nujum [the Mas'udic canon], which includes not only
his astronomical tables but, in the tradition of al-Battani, a table of
geographical coordinates of important places throughout the world. This
table has over six hundred entries and hence is double the size of that
of al-Battani or of Ibn Yunus.
Al-Biruni was a first-rate scholar, interested in all branches of science,
though it is as a mathematician and an astronomer that he is remembered.
He was an excellent critic who read widely. He had good knowledge of Greek
scientific sources and was extremely interested in Indian scientific theories,
so that he could and did compare the different cultural streams that came
the way of the Muslim intelligentsia of his day.
In the geographical field it was mainly the mathematical and astronomical
aspects that interested him. Here he was specializing in those aspects that
had been neglected by previous geographers, and thus one might expect to
see an improvement in Islamic cartography.
Among the projects al-Biruni mentioned in some detail was the measurement
of the degree of latitude. He carried this out in Khwarazm and in Ghazna,
and he produced a new method of measurement by using a convenient mountain
from which the horizon could be observed. He also attempted to measure the
difference in longitude between two places using the distance between them
in miles. This was difficult, since the direct distances between places
could not be worked out with any accuracy. However, he produced a result
for the longitude of Ghazna east of Baghdad, setting out the theory behind
this operation so that it was there for any later scholar to improve. He
also gave a complicated theory based on this for calculating the qibla,
or the directions of Mecca from any place. Al-Biruni also criticized the
projections of Ptolemy and Marinus, and by the latter he obviously meant
the rectangular projection as shown us by Suhrab. In his works he gives
the theory behind two different projections, one of which would be known
today as an azimuthal equidistant projection and the other as a globular
projection. Finally, he made scientific comments on the distribution of
land and water on the face of the globe.
Few of these points were taken up by al-Biruni's successors, and his scientific
work exerted very little influence on future Islamic cartographers. No one
took the azimuthal projection, drew a graticule, and placed toponyms in
their proper places. If al-Biruni himself did so, we have no surviving examples,
and his successors do not mention it. Al-Biruni's latitude and longitude
refinements are incorporated in his tables and were copied to some extent
after his death. Perhaps the most accepted piece of information was the
distribution of land and water, because the eastern extension of southern
Africa toward China, which was a prominent feature of the Islamic world
map up to al-BIrum's time, was now discontinued. Only al-ldrisi (Slide #219) and direct copies of earlier maps like those
of the Balkhi school insisted that the African landmass filled the
southern part of the oikoumene [known world] from west to east. Al-Biruni's
only direct contribution to cartography was a sketch map showing this distribution.
It appears in the manuscripts of the Kitab al-tafhim li-awa'il sina'at
al-tanjim [Book of instruction on the principles of the art of astrology],
copied 1238, and is his version of the circular world map showing how independent
his thought was from the contemporary standard of Islamic cartography. He
so reduced this eastward extension of Africa, which was a legacy of Ptolemy,
that the Indian Ocean appeared to cover the whole Southern Hemisphere. This
sketch map was occasionally used directly by later authors-for instance,
al-Qazwini in his cosmographical work 'Aja'ib al-makhluqat (Slide #222), but its influence was very clear in practically
all future Islamic maps of the world.
LOCATION: British Library, MS. Or. 8349, fol. 58a, London
REFERENCES:
*Harley, J.B., The History of Cartography, Volume Two, pp. 141-142, Figure
6.4.
*illustrated