A Conversation for Sundials

up the wall

Post 1

Taff Agent of kaos

How do you set up a sundial that is vertical on a wall??????smiley - erm

up the wall

Post 2

Gnomon - time to move on

The wall should be south facing (assuming you're in the Northern Hemisphere).

Find out your latitude from a map or atlas and subtract it from 90.

The gnomon should point downwards and the angle between the gnomon and the wall should be this angle.

If the wall isn't south facing, it's going to be more complicated. The shadow-casting line of the gnomon has to be parallel to the axis of the earth, so you'll have to use a bit of geometry to work it out.

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