Archimedes' sunwidth measurement
Illustration of Archimedes' (Sand Reckoner, 1.10-1.16) measurement of the Sun's angular width.
In the Sand Reckoner (1.10-1.16), Archimedes describes how he measured the Sun's angular width.
Place the cylinders close to or far away from the target (leftmost point). Follow Archimedes' instructions (as displayed in the illustration), and you will also find upper and lower bounds for the Sun's angular width which, for illustrative reasons, has been set here to about 20 degrees, while the real value is 0.5 degrees. For more realistic settings, make R one tenth of a mm bigger than r and set the distance d between the cylinders at about 22.8825 mm.