The Tauʻolunga sundial

The sundial is on a west facing wall, so the gnomon only casts a shadow in the afternoon for about 3 hours until sunset. But a mirror reflects the sun in the morning for about 3 hours after sunrise. So in the middle of the day (10 or 11 o'clock until 14 or 15 o'clock) there is not much to be seen. Also high trees around the place may obsure the sun when closer to the horizon. And finally irregular plastering of the wall may introduce some slight inaccuracies from time to time.

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On a cloudy day

the wall

The real thing: 4 m wide, 2½ m high

Show 2 3 4 × enlarged

Winter solstice morning

winter morning

The sun reaches its rightmost position. 10:00

Winter solstice afternoon

winter afternoon

The sun reaches its rightmost position. 15:20

legend

There are in fact 4 sundials in 1 drawing. Select the right lines to read the proper time. Reddish is spring (Jun—Dec), greenish is autumn (Dec—Jun). Darker colours are for the afternoon. The lighter ones for the morning, but on the real wall itself they are made lighter by being dotted.

Spring equinox morning

winter morning

The sun reaches its middle position. Morning

Spring equinox afternoon

winter afternoon

The sun reaches its middle position. Evening

Autumn equinox morning

winter morning

The sun reaches its middle position. Morning

Autumn equinox afternoon

winter afternoon

The sun reaches its middle position. Evening

gnomon

The gnomon with the mirror.