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Error Analysis of a Monumental Garden Variety Sundial Roger Bailey NASS 2009 Portland, OR ©Phil Palies Questions for NASS Registrar How do I register this sundial? Now under construction at Soap Lake WA Is there a sundial expert we can consult? Artist’s rendering from website
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Error Analysis of a Monumental Garden Variety Sundial Roger Bailey NASS 2009 Portland, OR ©Phil Palies
Questions for NASS Registrar • How do I register this sundial? • Now under construction at Soap Lake WA • Is there a sundial expert we can consult? Artist’s rendering from website http://www.soaplakememorialstones.com Is this a Sundial?
Response from NASS “Expert” • A sundial is an instrument designed to tell time • The gnomon must be straight and at the correct angle • The hour lines depend on the location and are different for each hour. • What is now cast in bronze & cement? Artist’s rendering from website http://www.soaplakememorialstones.com Data & pictures required On angles, size, location,etc
Orientation • Use the sun’s shadow to determine the orientation • Table of times when the sun is south, east or west • Spreadsheet corrected for EQT and Longitude Date DOY Declination EQT EQT º Noon South Sun West Sun East 16-May-2009 135 19.20 3.6 0.910 12:54:19 17:39:36 8:09:01 17-May-2009 136 19.42 3.6 0.903 12:54:20 17:38:39 8:10:02 18-May-2009 137 19.64 3.6 0.894 12:54:23 17:37:43 8:11:02 19-May-2009 138 19.86 3.5 0.882 12:54:25 17:36:49 8:12:02 20-May-2009 139 20.06 3.5 0.868 12:54:29 17:35:57 8:13:00 21-May-2009 140 20.27 3.4 0.851 12:54:33 17:35:07 8:13:58 22-May-2009 141 20.47 3.3 0.833 12:54:37 17:34:19 8:14:56 23-May-2009 142 20.66 3.2 0.812 12:54:42 17:33:32 8:15:52 24-May-2009 143 20.84 3.2 0.789 12:54:48 17:32:48 8:16:48 25-May-2009 144 21.02 3.1 0.765 12:54:54 17:32:05 8:17:42 26-May-2009 145 21.20 3.0 0.738 12:55:00 17:31:24 8:18:36
Soap Lake, WA Mineral Milligrams/Liter Sodium 5760 Bicarbonate 2480 Sulfate 2540 Carbonate 3840 Chloride 2290 Potassium 504 Organic nitrogen 0.9 Fluoride 7.2 Ortho-phosphate 6.3 Nitrate 0.7 Calcium 2.5 Magnesium 2.9
Healing Waters • Spa treatment like the thermal mineral baths in Europe • Bathing in the alkali waters, soaking in the mud, cures people afflicted with Buerger's disease and other ailments [ www.geocaching.com GC1DJWD
Modern Spa Treatment • Spa treatment is now an sensual indulgent luxury • ‘You deserve it” • Hot rocks • Hot oil massage • Aromatherapy • Soap Lake missed the market • “Calling the healing Waters” a new focus
Concept • Centre of Interest for Soap Lake • Build it and they will come • Theme: Calling the healing waters • Reflects ethnic and historical themes • Mighty winger warrior protecting and comforting maiden with catch basin for healing waters
Installation of basalt columns Angles and offsets are obvious
Error Analysis • Sculpture is a poor sundial • A worst case scenario • Feathered arm at ~37º but curved and offset from center • Base at ~30º is offset vertically • Various parts of the structure cast shadows on the hour lines on the base
Error Minimazation Considerations • Users: • People going to the park to enjoy the beach and water. • Good time not regimented time • Season: • Summer not winter • Spring and fall if the weather is good • Time • 9 AM to 5 PM Summer • Peak mid-afternoon • Impression: • Form follows fashion, not function • Looking good is most important
Sundial Considerations • Can the sundial work? • giving an impression of time • When most people will see it • Design for summer, solar noon +/- four hours • Design based on a point gnomon, the tip of the feather • Calculate design for 47º • Hold the gnomon tip fixed • Move the base intersection to 37º design • Calculate shadow planes for 37º at various times of day and declinations of the year • Choose the best compromise considering use • Design is fit for purpose
Shadow Plane Analysis • The 37º gnomon has a shadow plane • Shadow plane intersects the base at a specific angle • Shadow angle (SA) varies through the seasons • Tan SA= Sin G x Sin Az/ Cos G x Tan Alt +Cos G x Cos Az • giving an impression of time • When most people will see it • Spreadsheet used to calculate altitude, azimith and the declination, latitude and time angle • Sin Alt = Sin Dec x Sin Lat + Cos Dec x Cos Lat x Cos t • Shadow angle calculated from altitude, azimuth and gnomon angle • Plotted on sundial design by Zon 2000 with DeltaCad • "Error Analysis of The Horizontal Sundial-I" Lauoesch & Edinger, NASS Compendium 2-3, Sept 95
Artists • David Govedere Sculptor • Keith Powell Artist • Concept accepted in 1994 • Bronze sculpture cast in 2003 ©Phil Palies
Finished Sculpture • Curved offset feathered arm as gnomon • Hour Lines and Posts • Solar Noon +/- four hours • 9AM to 5 PM © Raymond Gravelle
Time Check XII • XII is XI solar • Hour Line band = post widths • Tip of shadow in the middle of hour band • Curve and offset of feathered arm is obvious • Time check OK © Raymond Gravelle
Time Check III • III solar II • Again the tip of the feathered arm tells the time • Hour lines diverging • Time check OK © Raymond Gravelle
Summary • Objectives met • Sculpture looks good, an excellent focal point on the Soap Lake beach • Sundial is fit for purpose • Time indications OK in the summer 9AM to 5 PM © Raymond Gravelle
Toolbox • NASS Compendium & Presentations • “Error Analysis of The Horizontal Sundial" Lauoesch & Edinger • “Error Analysis of Garden Variety Sundials” • Software: Zon 2000, DeltaCad, Excel • Spreadsheets: • Error Analysis Garden Variety Sundials • Shadow Angles • Meridians and Prime Vertical
Acknowledgements • Raymond Gravelle: Challenge, data, photographs, patience • Larry McDavid: Asking the right questions • Phil Palios “Philthy Photography” Photos of the dedication ceremony at http://www.flickr.com/photos/philthy_photography/sets/72157620424323215/