then thy face towards the Sacred Mosque: wherever ye are, turn your
faces towards it... (Qur'an 2: 144)
grid, likely of 17th-century origin, gives the distance and
direction to Mecca (center) for any place in the Islamic
world. Detail shows the pointer, marked with a distance scale;
the grid scale (at top of grid); and names of localities.
courtesy of Christie's, London.
centuries, Muslims all over the world have obeyed this command from
the Koran, facing Mecca five times a day for prayer. But for a Muslim
who is thousands of miles from Mecca, finding the right direction to
pray-the qibla, or "sacred direction"-is not so easy.
It has even been a source of controversy. Some of the mosques in Cairo
reflect two different qibla values at 10 degrees from each other, with
the outside walls aligned to one and the inside walls to the other. In
North America, some Muslims pray to the northeast, in the direction of
the great-circle route (the shortest path along the planet's
surface) to Mecca, whereas others pray to the southeast.
Muslims were using sophisticated mathematics to solve this problem
centuries before the equivalent discoveries were made in Europe. At a
time when Europeans believed that the Earth was flat, Muslim
scientists knew how to correct for the Earth's curvature. Two
recently discovered instruments have proved that Islamic
mathematicians were even further ahead of their time than anyone knew.
These Mecca-centered world maps, cast in brass, indicate the direction
and distance to Mecca from any point in the medieval Muslim world, and
they do so with a type of map projection that was unknown in the West
until the 20th century.
had been working on the subject [of the qibla] for 20 years, and the
discovery of these maps took me by surprise," says David King, a
historian of science at the Johann Wolfgang Goethe University in
Frankfurt, Germany. For the last decade King has been working to
discover who made the maps and, more important, who designed them. All
the evidence suggests that they were fabricated near Isfahan, in
present-day Iran, during the Safavid dynasty (which began in 1502 and
ended in 1722). However, King believes that the grid that is the maps' most distinctive feature must have been discovered centuries
first of the two maps surfaced in 1989, when it was auctioned at
Sotheby's of London. An anonymous collector discovered the second
one at a Parisian antique dealership in 1995. The two instruments are
so similar that they may have come from the same workshop. They are
about 9 inches wide and originally came with three attachments: a
compass, a sundial, and a rotating pointer that indicates both the
direction and distance to Mecca. The base contains a curved grid of
latitudes and longitudes, with the latitudes represented by circles
and the longitudes by vertical lines; more than 100 holes are punched
into the bronze to indicate various locations. (Mecca is, of course,
at the center.) Because the instrument was not meant for navigation,
it looks like no map you have ever seen: There are no land forms, no
rivers, no oceans.
not surprising that they had the data to enter onto the grid, and the
motivation [to find the qibla],Ó" says Len Berggren, a historian of
mathematics at Simon Fraser University in Vancouver. "What is
surprising is that someone discovered the map projection to do it."
Not only are the lines of latitude curved and the lines of longitude
unevenly spaced-both unprecedented innovations in the Islamic world-but the spacing is precisely calibrated so that the distance
to Mecca on the pointer is the sine of angular distance to
Mecca in the real world. If the lines had been evenly spaced, the
instrument would not have worked.
to King, the artisans of Isfahan could never have come up with such a
grid themselves; they were accomplished astrolabe makers, but not
mathematicians. Therefore, they had to be copying an earlier model.
did the original model come from? King has some intriguing
speculations. As early as the 9th century, Islamic astronomers had
devised a method for computing the qibla that happened to produce, as
an intermediate step, the sine of the distance to Mecca. The map
projections might have been discovered at the same time. Indeed, King's colleague Francois Charette has shown that the grids are, in
a sense, a translation of the equations into cartographic form.
Alternatively, a later scholar who was familiar with the trigonometric
method might have devised the map as an ingenious simplification. King
suspects Abu 'l-Rayhan al-Biruni (973-1048), considered the
leading scientist of medieval Islam, who lived in Ghazna (now
Afghanistan) and wrote an influential and original treatise on the
less romantic possibilities have been suggested. The catalogue that
Sotheby's printed when the first instrument went up for auction
states: "The projection is of western European inspiration ... and
this unusual instrument is interesting as evidence of the assimilation
of European science and technology in Persia in the 18th century."
King strongly disagrees with that interpretation, citing both physical
and historical evidence. Even if European mathematicians had worked on
the qibla-finding problem, he argues, they would not have stumbled on
a solution that was directly inspired by a 9th-century Islamic
formula. "The fact that the instrument uses the sine of the distance
is, to me, the most compelling argument" for its early Islamic
origin, King says. There is also no evidence that the European
scholars who were in Persia at the time brought with them anything
like a Mecca-centered world map. Even if they could have, they would
not have wanted to: They were in Persia to convert Muslims, not to
make it easier for them to practice their religion.
clues to the origin of these instruments may yet come to light. "So
many Arabic manuscripts lie not only unstudied but uncatalogued in the
libraries of the world," Berggren says. They may contain
descriptions of similar qibla-finding world maps, which went
unrecognized before because historians didn't know what they were
reading about. Says Berggren, "Not only do we know what to look for
now, but we know it's worth looking."-Dana Mackenzie
article is published by written permission from American
Magazine of Sigma Xi, The Sceintific Research Society. Articles was
originally published in the Science Observer, May-June, 2001