On Mon, Oct 31, 2016 at 08:24:04AM +1100, Karl Billeter wrote: > On Sun, Oct 30, 2016 at 02:37:04PM +0000, Frank King wrote: > > ... > > Almost the first task is to find > > the centre and the axes. Clearly > > you cannot fold a slate in half > > and the traditional way to proceed > > is to put a large sheet of paper > > over the slate and crease it down > > all round the rim. > > > > You then cut round the crease and > > attempt to follow your procedure! > > Wrap the slate with a reflective strip (smooth, shiny plastic? thin polished > metal?). Playing around with a laser should find the focii.
You could also try balancing the slate on rod to find the centre but it's probably too hard to get the required accuracy and it might be a little risky! K --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
