A plotting Instrument for sundials on irregular surfaces

1
A plotting Instrument for sundials on irregular
surfaces

• Gérard Labrosse

2
Introduction

• Methodical put in function
• Indispensable presence of the sun

3
Advantages

• Two perpendiculary lasers
• Possibility of lay out big sundials highly
  positioned
• Not necessary to know the declination of the wall

4
Latitude settings

• 12 intervals match to a graduated sector of 23
• Precision of 5 minutes of arc

5
Billsticking of the hour angle H

• Ball pushed by a coin (7,5)
• Any other hour angle

6
Billsticking of the declination

• Solstices and equinoxes positioned with 3 holes
  an axis with symbol d

• For any declination of the sunthe disc can be
  blocked with a small plastic stopper which is
  pusched with a screw (with a sun decoration)

7
Horizontality adjustment

• An aluminium tray with 15,75" on each side  
• 3 screws for adjustment

• Double precise spirit level

8
Alignment on the local meridian

• A compass for a first rough alignment

• A viewfinder with a lens and a target

9
Drawing the hour lines

• Adjust the position of the lower disc on the
  value of the hour angle (15 for 13h)
• Pivot the upper disc from the top to the bottom

10
Drawing the diurn curves

• Adjust the value of the sun declination value of
  the hour angle
• You just have to pivot the upper part from left
  to right

11
Style installation

• The style is positioned in a way that the laser
  point is visible on its end

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Œuvres du Père Pardies
13
With a lamp
14
A plotting Instrument for sundials on irregular
surfaces

• Gérard Labrosse