Hi Fer, Now I am starting to see the low latitude problem for azimuth dials - which was the original problem described by John C. But for him, at 33 degrees latitude, a vertical south facing dial (equal to one at 57S) would be better than horizontal - but for me a vertical decliner would be worse. I will take the suggestion to use a vertical line for the shadow maker and see what I get. Ref:June 1996 issue of the BSS on "Azimuth Sundials Horizontal and Vertical" by G. Fantoni
Thanks, Warren "fer j. de vries" wrote: > Hello Warren, > > Lets start again : > > Latitude = 42 > Inclination of dial = 90 > Declination of dial = 64 > > Calculated: > style height v = -19.01 > substyle at b = -135.05 > longitude correction ts = 71.93 > > Now we have to deal with a horizontal azimuthal sundial at low latitude : > 19.01S, that is even between the tropics. > This will give problems with the hourlines if the sun's declination is near > or > lower then -19.01 degrees. > ( that is about half november untill end january ) > During that period some hourlines will cross each other and you can't get a > good reading of the time. > To show this I calculated an example for lat. -19.01. > This example is for local suntime, just to show the effect. > ( Only one half of the dial is in the picture. Mirror this side to get the > full dial ) > So I think that your wall isn't very suitable for such an azimuthal dial, > with a style perpendicular to the wall. > > In stead of using the azimuth of 19.01 degrees South use your own azimuth by > making a dial with a vertical style parallel to your wall. > As date lines you could use horizontal parallel lines. > > Remark : > Spin.exe as distributed can't calculate dials between latitude 25N and 25S. > These restrictions were made because of the shown problems. > > Happy dialling, Fer. > > Fer J. de Vries > [EMAIL PROTECTED] > http://www.iae.nl/users/ferdv/ > Eindhoven, Netherlands > lat. 51:30 N long. 5:30 E
