A plotting Instrument for

sundials on irregular surfacesGérard Labrosse

2

Introduction

Methodical put in function Indispensable presence of

the sun

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Advantages

Two perpendiculary lasers

Possibility of lay out big sundials highly positioned

Not necessary to know the declination of the wall

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Latitude settings

12 intervals match to a graduated sector of 23°

Precision of 5 minutes of arc

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Billsticking of the hour angle H

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

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Billsticking of the declination Solstices and equinoxes positioned with

3 holes: an axis with symbol

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

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

Double precise spirit level

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Alignment on the local meridian

A compass for a first rough alignment

A viewfinder with a lens and a target

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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

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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

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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

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With a lamp

A plotting Instrument for

sundials on irregular surfacesGérard Labrosse