REVOLUTIONARY NEW CALENDAR

A couple of days ago, Wilson asked me whether I had an old battery-powered clock that didn't work any more.
I fished one out of my 'JUNK – but might be useful' drawer and gave it to him, and he ran off with it to his study.
Today, he presented me with this:
Each day you advance the long white 'day' hand one position and the shorter 'month' hand will automatically move by means of the clock mechanism it's attached to!
In the picture you can just make out Wilson advancing the day hand to today's date!
In addition to the date it also tracks the seasons of the year and signs of the Zodiac.
It's extremely clever – ingenious even – but I can't see it making him rich…
If you've got an old clock that no longer works and you'd like to try this for yourself, I'll ask Wilson to post a big picture of the calendar face design – just let me know.