An Early/Late Christmas Present?

While visiting Mum last week I had to get out of bed early to take delivery of a package from the Postman. "Oh good" says Mum "its your Christmas present - I'm glad it came while you were here!"

Now I'm pretty sure I had some very satisfactory presents from Mum last Christmas, and being April it's surely too soon for next Christmas. But Mum said she wasn't happy with my gifts and confirmed it was my Christmas present. Who am I to argue with my Mother? Thanks Mum!

An armillary sundial is based on an ancient device used to measure time based on the location of the sun on the horizon. An armillary uses a shadow stick, or gnomon, to pinpoint the hour of the day. As the sun progresses over the horizon, the shadow produced by the sun will be cast in a clockwise movement.