## Monday, September 23, 2013

This wall sun clock in my header was taken while I traveled in Germany.  I saw a number of these, some simple in design and structure and others much more elaborate with a lovely painting as a background.  If the angles are even slightly off you will never get the correct time.  The clock has to be aligned parallel to the axis of the earth's rotation.  I am not sure how this works with the changing of the seasons and dropping angle of the sun.  That is way too much math for me!  i.e. "Since the gnomon's style must be parallel to the Earth's axis, it always "points" true North and its angle with the horizontal will equal the sundial's geographical latitude; on a direct south dial, its angle with the vertical face of the dial will equal the co-latitude, or 90° minus the latitude."

Just ONE image in this formula from wikipedia.

$\tan \theta = \frac{\cos \lambda}{\sin \eta \sin \lambda + \cos \eta \cot(15^{\circ} \times t)}$

I, of course, was more fascinated that it seemed to be an incorrect time when compared with my watch and I was enjoying the beauty of the swatches and swishes.

Joseph Pulikotil said...

Fantastic header photo and a very interesting write up. Best wishes

kenju said...

I love the curves. It is beautiful and I don't care if it keeps time or not....LOL

Stephen Hayes said...

Pretty and very interesting, but I doubt I could tell time on this thing even if it did keep correct time. Have a great week.

Kerry said...

Isn't that the coolest clock ever? "Faith, hope, love are in the clockwork" is my reading of the German words. If Ursula pays you a visit I bet she will give you a better translation.

Tabor said...

So nice, Kerry, I was waiting for someone to translate. It is in the courtyard of a Catholic church.

Brighid said...

Thanks to Kerry for the translation, and to you for the cool pic...

Celia said...

Beautiful, as for the formula eek! Love the information you post.

messymimi said...

Those are pretty. They may well be "off" by our modern timepieces, mostly because we do things like Daylight Saving Time. There may be other reasons for the apparent differences, too, including that they used to consider noon local time to be when the sun was directly overhead, not when the neighboring town's clock said so, since you couldn't get there very fast anyway.

A Cuban In London said...

Damn, that's a beautiful header. And the explanation behind the design is just as good. Many thanks.

Greetings from London.

Linda Reeder said...

I'm with you on the swatches and swishes. I have no idea what that scientific explanation for that mathematical formula mean.

SueAnn Lommler said...

It is so beautiful...wow!!
Hugs
SueAnn

Olga said...

It is quite beautiful. I will trust you on the math part.

Mage said...

Faith, Hope, and Love indeed, but where are seven and eight? :)

colleen said...

The center of the hands seem to come right out of the window!

Hattie said...

That is very nice.

Friko said...

There are lots of houses with sundials, mainly in southern Germany. I think I’ll forego the maths and just enjoy the picture.

“Faith, Hope and Charity (love) lead the way through time.”

Very literally translated. It sounds better in the original.