The Linear Astrolabe of al-Tusi

You are looking at an artist’s rendition of a device known as “the staff of al-Tusi” which sounds like a magical weapon straight out of Tolkien but in fact was a genius scientific tool made by one of the most important mathematicians in history.

Sharaf al-Din al-Muzaffar al-Tusi (c. 1135-1213) lived in various cities in what is now modern Iran and Syria during the Golden Age of Islam, and he advanced the subject of Calculus by inventing the idea of a function centuries before Gottfried Leibniz/Issac Newton.

He was super practical and not explicit in his methodology — so although he figured out a way to give an approximation of the root of a cubic equation, the theoretical significance of his ideas wasn’t promoted.

And similar with his staff here. Astrolabes were super important for figuring out direction, and he made this one to look like a slide rule versus the usual fancier but more technical versions. It could figure out things like the height of a celestial body and determining time with the sun and also at night with the stars — but it was built for al-Tusi’s latitude, and for the celestial bodies in a particular stage of ascension and declination, making it accurate for only about 50 years.

Al-Tusi taught many future scholars of the day. How and to what degree he and others specifically contributed to Leibniz and Newton’s mathematical inventions are still debated.