Looking closely at the photo, I saw some interesting details: Below the water-filled 'gnomon', there is a semicylinderical, angled "wall", apparently to catch the index spot. (About 2 radii from the center of the cylinder)
Why is there a gap in the wall, about noon (1300 Summer Time)? Above the gnomon, there appears to be a small pyramidal point, that would cast a shadow inside the bright spot, at local noon? Does the gnomon cylinder look tilted to anyone else? (Not perpendicular to the dial plate) Very interesting design! Dave > From: Andrew James <[EMAIL PROTECTED]> > To: 'Steve Lelievre' <[EMAIL PROTECTED]>; Sundial mailing list > <sundial@rrz.uni-koeln.de> > Sent: Wednesday, June 07, 2000 9:38 AM > Subject: RE: Water filled sundial at Herstmonceux > > > > There are a number of these around (the one I remember seeing is at the > > Manor House Museum, Bury St Edmunds) - it's a registered design but I > can't > > remember the details though I think it was 1960s or perhaps later. > > Basically the cylinder and liquid acts as a cylindrical lens which focuses > a > > bright spot (the intersection of a bright line with the equatorial plane) > > onto the scale. It only works in summer because it's an upper surface > > equatorial! It would work with solid plastic or glass but I expect that > it > > is made like that because liquid filled is cheaper ... > > > > Andrew James > > > > -----Original Message----- > > From: Steve Lelievre [mailto:[EMAIL PROTECTED] > > Sent: 07 June 2000 16:29 > > To: Sundial mailing list > > Subject: Water filled sundial at Herstmonceux, England, ... > > ... > > photo is at http://www.ualberta.ca/~droles/astro/astrav/Sun2.html
