Originally posted by retsam1:

The map is actually your sundial in a way. Face the direction that the sun is in and your direction is the point on the clock through the map(with N midnight and S being midday) on the map.

I know it aint really useful, but it makes for a nice deco item you can build.. the smaller clock I showed is in my 2 tier garden (lower tier and upper tier, lower for plants, top for seeds usually).
I mean if you really want to know the time, there is a mod that adds either a digital or simple clock.