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Philippi Dial /
Sundial of Parmenion /
Greek Armillary Dial

Universal, Altitude, Seasonal hours

The Greek dial commonly referred to as the "Philippi dial" operates under the same system of approximation as the universal Roman altitude dial.

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It carries an aspect of the armillary sphere lineage, sharing certain traits with later armillary-inspired dials such as the astronomical ring and universal equatorial ring. Like these two dials, the Philippi dial can act as a self-orienting solar compass.

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The dial is suited for use at four key latitudes, corresponding on the four cities stationed at the end of each cut meridian ring. These locations include Alexandria (31º), Rhodes (36º), Rome (41º), and Vienna (45º)*.

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*While Vienna's date scale is calculated for 45º, the modern latitude value for the city is 48º.

sundial1.jpg

The Horologion of Philippi

Digital Heritage Research Lab

History of Portable Sundials

Helmut Sonderegger

How to use

1. Unfold the meridian ring which carries the latitude of use. This ring should be kept perpendicular to the dial.

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2. Locate the current month along the ring segment's arc, and position the bottom of the inner, hour ring over the date of operation.

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3. Suspend the dial, leveling it to the local horizon.

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4. Rotate the dial until a beam of light is projected through the nodus onto the inner hour scale. Spin the dial so that the point of light sits at the center line running along the hour band.

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5. Read the position of the beam on the scale. At the end of the sixth hour, it will be centered on the ring's midway point.

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Overview of Instrument
Outdoor Demonstration
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