More than a thousand years after these Middle Kingdom coffin lids, highly engineered mechanical star trackers (astrolabes) were used to calculate the time at ni

More than a thousand years after these Middle Kingdom coffin lids, highly engineered mechanical star trackers (astrolabes) were used to calculate the time at night. Here’s a letter accompanying the gift of a gold and silver astrolabe from the Lybian philosopher Synesius to a Byzantine general. Interestingly, it shows that Hypatia of Alexandria contributed to the design of Synesius’ Astrolabe. It further indicates that Astrolabes could be used as “night clocks” and as instruments of philosophical investigation. https://www.livius.org/sources/content/synesius/synesius-on-an-astrolabe/synesius-on-an-astrolabe-3/ https://www.livius.org/sources/content/synesius/synesius-on-... “I am therefore offering you a gift most befitting for me to give, and for you to receive. It is a work of my own devising, including all that she, my most reverend teacher [Hypatia], helped to contribute, and it was executed by the best hand to be found in our country in the art of the silversmiths” The letter also discusses how much geometry and astronomy had progressed since the time of Ptolemy. Hypatia’s father, Theon of Alexandria, had recently published “Euclid’s Elements of Geometry,” the most successful and influential geometry textbook of all time. I’ll note that this work was almost certainly produced with the help of his mathematical genius daughter, even if she wasn’t formally credited. But nice to see Synesius credit her so directly here, in the production of this mechanical star computer (as I believe an astrolabe has right to be called). And, while he did not credit the Egyptians, he credits the beginnings of the Greek philosophical knowledge of the stars to Pythagoras (who is claimed by Iamblichus to have become an Egyptian priest).