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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
Error Analysis of a Monumental Garden Variety Sundial

Roger Bailey

NASS 2009

Portland, OR

©Phil Palies

questions for nass registrar
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
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
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

slide9

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
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
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
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
slide14

Installation of basalt columns

Angles and offsets

are obvious

error analysis
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
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
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
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
Artists
  • David Govedere Sculptor
  • Keith Powell Artist
  • Concept accepted in 1994
  • Bronze sculpture cast in 2003

©Phil Palies

finished sculpture
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
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
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
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
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
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/