British Museum 8 - Qibla Pointer
A little bigger than the one I use now, but still functional I imagine.
Details on the Qibla Pointer:
"Ivory sundial and Qibla pointer (Bayram b. Ilyas, Ottoman Turkey AH 990/1582-3 AD)
On this very unusual combined instrument the string casts a shadow on the sail shaped sundial in the centre, while the surrounding area is marked with the information needed for a qibla pointer."
The Qibla is the direction of the Kaaba.
Part of my visit to London included an afternoon at the British Museum. In that short time there was only so much I could see, but I loved just standing in the courtyard and watching people. Or the exhibits I did manage to get to - Ancient Egypt, less Ancient Egypt, China, Islamic Art.