Hi John, I have a problem with the word analemmatics.
Case 1 Do you mean an analemmatic sundial, with hourpoints on an ellipse and a moving vertical pin gnomon? Case 2 Or a dial with the curves for EoT correction ( = analemma in English ) In the second case you just subtract 3 degrees from the latitude and calculate the dial. But I think you mean the first case: the analemmatic dial. Do you want to use a human as gnomon? The gnomon then is vertical. The human won't correct himself for 3 degrees. You have to calculate the dial as an usual horizontal dial. The hourpoints and datepoints have to be projected vertical to the sloping plane. However, the inaccurate position of the human on the datescale and its wide shadow makes the dial not a pricision instrument, so don't bother and just draw the dial's pattern for the latutude on the sloping plane. The slope only is 3 degrees. (Don't do this if the slope is a large amount of degrees.) If you want a more presize instrument and will use a thin verical rod follow the described projection procedure. Another problem is how to keep the rod exact vertical. If you rotate it on the sloping plane it won't keep its vertical position. A human is able to do this automaticaly...... Or calculate the dial for the corrected latitude and use a rod perpendicular to the sloping plane. The rod isn't vertical now. This rod keeps the correct position if rotated. Tell me what choices you make. Best wishes ( from the Coll Watermill ) Fer. Fer J. de Vries mailto:[EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E ----- Original Message ----- From: "John Carmichael" <[EMAIL PROTECTED]> To: "Sundial List" <[email protected]> Cc: "Frans W. MAES" <[EMAIL PROTECTED]> Sent: Monday, April 15, 2002 6:15 PM Subject: Sloping Analemmatics > Hi All: > > I have a question. > > I use the Delta Cad macros to design analemmatics. These macros only permit > the design of analemmatics that have flat horizontal faces. But I need to > design an analemmatic that is painted on cement that slopes slightly to the > south. Let's say the angle of slope is 3 degrees from horizontal and the > latitude of the sundial is at 32.5 N.degrees. > > I thinking that if imput into the DC macro a false latitude of 32.5* - 3* = > 31.5 degrees that it would produce the correct drawing for the sloping > sundial. > > Is my thinking correct on this? > > Thanks anyone > > John > > John L. Carmichael Jr. > Sundial Sculptures > 925 E. Foothills Dr. > Tucson Arizona 85718 > USA > > Tel: 520-696-1709 > Email: [EMAIL PROTECTED] > Website: <http://www.sundialsculptures.com> > > > - -
