Message text written by INTERNET:[email protected] >Hi all, I am as ignorant as Alexei, so I'd gratefully apreciate any hint (or link) on what a shadow sharpener exactly is.<
It's a device to 'focus' the penumbra around the shadow of a gnomon edge so that the actual position of the shadow may be better determined. The ones we have recently been talking about - and the ones we discussed in May 1999 (it's a common toopic on the sundial mail list!) are all made from a pinhole (1-2mm diam) in a piece of card - they use the same principles as a pin-hole camera. Patrick ------------------------------------------------------------------------- E-Mail: [EMAIL PROTECTED] Web: http://ourworld.compuserve.com/homepages/Patrick_Powers/ Lat: N 51d. 49m. 09s: Long: W 00d. 21m. 53s -
