13 September 2019

“Non-standard astrolabes were basically 11th century gadgets”

Medieval manuscripts about astrolabes reconstructed

One of the manuscripts by Al-Biruni

In his PhD thesis, Pouyan Rezvani presents a reconstructed, translated and annotated version of two medieval manuscripts about the astrolabe, an ancient astronomical instrument. Both works were authored by Al-Biruni (973-1048), one of the most prolific scientists of the Islamic Middle Ages. “Reconstructing the manuscripts was quite a puzzle, since the original copies were lost,” Rezvani explains. He will defend his PhD thesis, which he wrote under the supervision of Prof. Jan Hogendijk, on 25 September.

Of the 26 still existing works by Al-Biruni, 24 had previously been published. For his PhD research Rezvani reconstructed and translated the remaining two, and added context and explanation.

A non-standard astrolabe

11th century gadgets

Of the two manuscripts he studied, the first one was relatively easy, Rezvani says. “It is a description of standard astrolabes, which are quite well-documented. Also, there are at least ten copies of the manuscript worldwide, so I could choose the two best and clearest ones to work from.”

The second manuscript was a lot more complicated, since it deals with non-standard variants of the astrolabe. “These instruments were mostly made and used at courts. Basically, they were ‘gadgets’ of the 11th century.”

Quite a puzzle

Not only the subject matter, but also the text of the second manuscript was quite a puzzle. “The only remaining copy of the text dates from the 16th century, so about five centuries after the original manuscript. And the copyist was obviously not an expert on astrolabes. He made a lot of mistakes, skipped some words and even entire lines, and completely omitted all figures.”

To make matters more complicated, the manuscript was written in very flowery prose. “Al-Biruni was not only a scientist, but also a poet. Also, he wrote the manuscripts in Arabic, which was not his native language, so the language is not very straightforward.”

It was also interesting to see the high level of the exact sciences in the Eastern Islamic world in the 11th century.
A richly decorated astrolabe

Beautiful and intricate

The astrolabe is a flat and portable astronomical instrument which represents the configuration of the heavens at any time of the day or night above and below the local horizon. This instrument was invented about 1600 years ago in the Hellenistic world and was further refined by Islamic scholars.

“The astrolabe is not only mathematically and historically relevant, but also artistically very interesting,” Rezvani says. “The instruments were very beautiful and intricate. The astrolabe can be used as a compass and also as a clock. Being from Iran myself, I was also interested in the way the manuscripts showed the high level of the exact sciences in the Eastern Islamic world in the 11th century.”