The nocturnal (or nocturlabe) is a very old instrument for telling time at night by measuring the stars. While concept is ancient, this design is all original. It is fully functional (all dials move properly) and meant to be worn as a pendant. This is now available for sale, as it has been tested and works nicely.
How to Use the Nocturnal:
The top of the nocturnal is where you see a bit of a ring around a spike. This ring can be strung with a chain and makes it possible to wear the nocturnal as a pendant. When reading the nocturnal, this end of the piece should always be up.
Your first step is to set the outermost dial on the date. The months are shown as letters, with January and December at the top, and the progression of the months running *counterclockwise*. Note that the exact position of the letter actually marks the middle of that month. Look closer at the piece and you will see the line that separates the months between the letters.
Now, hold your nocturnal up to the starry night sky, making sure that the date is still properly set. Locate the North Star centred in the hole in the middle of the Nocturnal. Then use the central dial (the one that looks like a pointer) to point to the two stars at the end of the bowl of the *big* dipper.
Once you have this all set. Look closer at the pointer and you will see that within the pointer is an eliptical ring and within this is a smaller pointer. This smaller pointer points to a roman numeral, which shows you the time.
Note again, that the roman numeral is centred on the middle of the hour. So, if the little pointer points in the centre of the numeral, it is in fact half past.
So now you can tell time at night without a powered time piece. This is great for night owls, vampires, and those who appreciate a gothic or steampunk look.