Western Dial

The Western dial is a particular type of vertical dial declining whose table is directed vis-a-vis the West.

The style of the dial is parallel to the table, and forms an angle $\ theta=- \ phi$ with the horizontal one, where $\ phi$ represents the latitude of the place.

The equator forms as for it an angle $\ theta= \ pi/2- \ phi$ with the horizontal one.

The time lines all are parallel between them, and their distance $d$ compared to the line of 18:00 on the equinoctial one is given by the relation

$d= \ alpha \ tan H, \,$

with $\ alpha$ the height of the style compared to the table, and $H$ the time angle compared to 6:00 of the evening. The distance between the lines of 15:00 and 18:00 is thus equal to the height of the style.

Like the polar Dial, its layout is independent of the latitude of the place: it depends only on the height of the style compared to the table.

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