Al-Quhi's perfect compass
Compás perfecto de al-Kuhi para trazar cónicas
- Date
- c. 980 · confidence medium
- Place
- Baghdad, Iraq
- Credited to
- Abu Sahl al-Quhi
- Field
- Knowledge & symbols
What it is
Instrument with one arm at a fixed incline and another telescopic, which when turned continuously traces circles, ellipses, parabolas and hyperbolas. It is the first described instrument able to draw all the conic sections.
The treatise survives and has been studied by R. Rashed; al-Quhi also directed the Sharaf al-Dawla observatory in Baghdad (988).
What it led to
- mechanical tracing of conic sections
- Renaissance ellipsographs and conic compasses
- Islamic constructive geometry