This question takes me back to when David Brown was creating an analemmatic dial for my young children's school. I advised that I thought it was too big, as they were small children. In the event, the dial is usable except for a small time daily in summer.
As you say, the worst case is noon at midsummer, which is counter-intuitive as this is when you are closest to the dial! I agree that you can hold your hands over your head, but, in practice, I have never seen anyone other than myself do it. Also, you should stand with your back to the sun so that your shadow is symmetrical. But nearly everyone stands facing north-south and twists their head to see the shadow. When the sun is low enough, the best shadow is formed by standing with your legs slightly apart and using the sliver of light between them. I would be inclined not to make the dial too big. It can be read to surprisingly good accuracy even if a modest size. Chris Lusby Taylor 51.4N, 1.3W ----- Original Message ----- From: "anselmo" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, April 08, 2005 7:23 AM Subject: On the greatest size of an analemmatic > Dear all, > > I need your opinions and advice on which could be the greatest > *effective* size of an analemmatic sundial for average latitudes. > > As you all know, for latitudes about 40 deg, the least longitude > of the style equals more or less the major semiaxis of the ellipse > so that the shadow can reach the ellipse on the worst case, this is, > at summer solstice noon. However, in practice it could be too > conservative to suppose so (who, except us, stands on an analemmatic > in the worst of summer?), and perhaps there are some practical rules > you know... Any hint? > > I am considering that the date scale can be on a 30 cm high step > where the user gets up to and that the user can rise his/her hand > so that the effective height of the style could be around 220 cm or so. > > Best regards, > > Anselmo > > > - > -
