Benno van Dalen
Historian of Science
with special interest in Islamic astronomy and transmission between
Islam and China, India and Europe.
Former editor of Historia
journal of history of
Research leader in the project Ptolemaeus
Arabus et Latinus at the Bavarian Academy of Sciences and
Humanities in Munich.
of this page: Research
Interests, Links, Address.
See also: my curriculum
vitae and list of
escape routes: Description
of my computer programs, Links.
To be added some time in the future: ZijManager, a
Windows program for entering, editing and mathematically analysing
medieval astronomical tables.
Recent changes on my webpages: This entry page, my list
of publications, and my curriculum vitae are more or less regularly
updated until all the information will be moved to a new personal
webpage associated with my current employer, the Bavarian Academy of
Science. PLEASE NOTE MY NEW EMAIL ADDRESS AT THE BOTTOM OF THIS PAGE!
Ancient and medieval astronomical
tables and methods of computation. Transmission of astronomical
from the Islamic world to China, India and Europe.
Since May 1, 2013,
I am employed at the Bavarian Academy of Sciences and Humanities in
Munich. Together with Dr. David Juste, I am research leader of the
new 25-year project Ptolemaeus
Arabus et Latinus (project leader: Prof. Dr. Dag Nikolaus Hasse,
University of Würzburg; commission: History of Science). Main
purpose of this project is to make available reproductions,
transcriptions and in the end editions of Ptolemy's astronomical and
astrological works (including pseudepigrapha) in Arabic and Latin
translations. Also further important works from the medieval Ptolemaic
tradition will be published and studied, including, among others,
commentaries on Ptolemy's works, zîjes
and other works heavily influenced by him. Brief information on
Ptolemaeus Arabus et Latinus is already available at the website of the Academy and that of Prof. Hasse. An extensive web interface,
through which the reproductions and transcriptions can be accessed with
numerous search facilities, will be set up in the coming year.
As part of the
project Ptolemaeus Arabus et Latinus,
to work on a revised «Survey Of Islamic
Astronomical Tables». The original monograph with this title was
E.S. Kennedy in 1956 (Transactions of the American Philosophical
Society N.S. 46-2, reprinted in 1989) and included brief
descriptions of little
more than 100 Islamic astronomical handbooks with tables (so-called zîjes),
extensive abstracts of 12 of these, a classification of the subjects
dealt with, and preliminary conclusions concerning the relations
the developments in the production of Islamic astronomical handbooks.
Nowadays, around 250 zîjes are known, of which nearly 150
are extant in more or less complete form, but only very few have been
published or investigated
The revised Zîj
Survey will include at least
At the moment
around 130 entries of zîjes
for the new Zîj Survey
are basically ready. They involve investigations of a large number of works that until now
have not yet been studied at all and hence provide the first
descriptions of the contents of these works.
- A complete list of all zîjes that are now known,
with information in a standardized form on the author and the locality
and time of compilation, references to primary and secondary
literature, and, for the extant works, a table of contents and
description of available manuscript sources.
- Descriptions of the ways in which various topics in zîjes
were treated in the course of the history of Islamic astronomy. These
descriptions will be based on representative groups of around 30 zîjes,
and will concern in particular topics that have received little
so far, such as the computation of eclipses and mathematical astrology.
- A systematic exposition of the underlying astronomical
parameters of as many as possible extant zîjes. These
parameters can be rapidly determined by means of recently developed
mathematical techniques and computer
and can in many cases be used to establish relationships between zîjes.
On the side, I hope
to publish my investigation of
the achievements of the Muslim astronomers who were
brought to China by the Mongols in the early Yuan Dynasty (around
1270). The available sources for this investigation are:
sources 1 and 2 are obviously two different works, a
mathematical investigation of their planetary tables shows that they
must be based on a common predecessor. It turns out that the two
sources share values for
most of the planetary parameters which are not found in any other
or Persian astronomical handbooks (including those resulting from the
observational program at the contemporary Ilkhan observatory in
It is therefore probable that their common predecessor was a work
by the Muslim astronomers who were active at the official Islamic
in the Chinese capital Beijing. The presence in one of the extant
of the Huihui-li of a large star
table independent of Ptolemy's
in the Almagest also points to original, hitherto unknown Islamic
- The Huihui-li (c. 1384), a Chinese translation of a
presumably Persian astronomical handbook with tables (a so-called zîj),
known to have been available in China in the beginning of the Yuan. The
Huihui-li is extant in a number of somewhat different
versions, apparently all deriving from a restoration of the original
translation carried out by an officer of the Astronomical Bureau of the
Ming dynasty in 1477.
- The Sanjufînî Zîj, an Arabic
astronomical handbook written for the Mongol viceroy of Tibet in 1366.
- An Arabic or Persian manuscript at the Pulkovo Observatory (near
St. Petersburg in Russia), which was obtained in China in the 19th
century and contains only a small set of astronomical tables.
According to a description
published in 1882, the manuscript listed above as source no. 3 is very
a partial copy of the original work on which both the Huihui-li
and the Sanjufînî
Unfortunately, the present whereabouts of the manuscript are unknown;
it may have been destroyed by the fire in the Pulkovo Observatory in
At the moment I am working
on an edition and English translation of, and extensive commentary on,
the Chinese text of the Huihui-li, which will be
published as a monograph
During my doctoral
research (under the supervision of Prof. Dr. Henk
Bos and Dr. Jan Hogendijk of the Mathematical Institute of Utrecht
University, Netherlands) I concentrated on the development and
application of statistical and numerical tools for the analysis of
ancient and medieval astronomical tables. In a number of examples in my
doctoral thesis Ancient and Mediaeval Astronomical Tables I
used these tools to derive the mathematical structure and underlying
parameters of a number of tables which had thus far defied explanation.
Furthermore, I wrote
programs for DOS-PC,
by means of which various tasks frequently occurring in research on
medieval astronomy can be conveniently carried out. These include:
sexagesimal calculations (also with trigonometric functions); calendar
conversions; input, analysis and output
of trigonometric, spherical-astronomical, and (pseudo-linear) mean
tables as they occur in Ptolemaic astronomy.
During a stay at the
Institute for History of Science in Frankfurt am Main (Germany) in
1997/1998 I developed a computer
parameter values occurring
in medieval Islamic astronomical texts and tables. This database
relies heavily on the hand-written parameter file of Prof. E.S.
Kennedy. It includes parameter values directly quoted in primary and
secondary sources, as well as values «squeezed» or
otherwise estimated from tables.
- Historia Mathematica: Elsevier's journal webpage
Mathematica: electronic version at Science Direct
- From China to Paris (eds. Y. Dold-Samplonius, B. van
Dalen, et al.): Steiner Verlag publication information
- From China to Paris: order from Amazon.de
- International Conference "Certainty, Doubt, Error: The
production of knowledge and its impediments in the practice of pre- and
early-modern sciende", held on November 17 and 18, 2001 at the Museum
für Angewandte Kunst in Frankfurt am Main
- Symposium Aspects of Early Astronomy and Mathematics:
Ancient Egypt, Ancient Greece, Islamic Middle Ages, held on July 7,
2006 at the Institut für Geschichte der Naturwissenschaften of
- Symposium India and Islam: Episodes from the History
of pre-Modern Astronomy, held on July 16, 2007 at the Institut für
Geschichte der Naturwissenschaften of Frankfurt University
- International Conference "Between Orient and Occident:
Transformation of Knowledge", held on November 6 and 7, 2009, at the
Lehrstuhl für Geschichte der Naturwissenschaften of the Ludwig
Maximilians University, Deutsches Museum, München
Benno van Dalen
Arabus et Latinus
Bayerische Akademie der Wissenschaften
recent modification: September 10, 2013.