George & Cornelia DeFossard: The Solar Time Clock Project

20140609_102147As my regular readers know, I don’t really have a lot to do with the world of clocks, but sometimes, there have to be exceptions.

I went to see friendsΒ of mine at their workshop in Frome – George deFossard and his wife Cornelia make exceptional clocks, and he is responsible for the movements, whilst his wife designs and makes the cases and dials. So far, they have done some great pieces, but nothing of the magnitude that they are attempting this time around! Sorry, but the photo of the two of them was blurred, so you have to live with just seeing George… a bit of a shame as Cornelia looks a lot better than George, but then again, I’m a bloke πŸ˜‰

The two are currently working on a solar time clock. This needs a bit of an explanation… The clock will show GMT on the left dial, and have a second dial on the right, that shows the day length, depending on your latitude, that can be adjusted, and the solar time, depending on your longitude, which can also be adjusted. The whole thing has to take the equation of time into consideration as well, and of course the day of the year, including the knowledge about leap years. To top all that, it will have a moon phase indication,a power reserve, and a nifty indication as to where in the world longitude and latitude of the clock are set to.

It took me quite a bit to get my head around all this, but I think I have finally managed on my drive back to my workshop πŸ˜‰

Here are some photos of what they have done so far. Please be aware that these are just mock-ups done in aluminium, and not the final parts that will end up in the clock.20140609_101645
This is a view of the shutters indicating the day length. So what you see here is a summer day pretty far up north or pretty far down south. with a very long day, and a very short night.20140609_101654

The same shutters indicating a longer night, and a shorter day, so it’s winter.

A hand will indicate the current solar time, coming through the middle of the shutters, so you can see sunrise, noon, and sunset on the dial. Of course adjusted to your longitude, latitude, and taking the equation of time into consideration!


The shutter mechanism from the back…20140609_111009

The shutter mechanism partially taken apart – go and count the balls of the ball bearing πŸ˜‰20140609_101715This is the date wheel, which turns once a year. It has 366 teeth. When it’s not a leap year, the lever enters the groove you can see, which will cause the wheel to be advanced by 2 teeth, e.g. from February 28th to March 1st. When it’s a leap year, the groove is blocked, and the wheel only advances one tooth, e.g. from February 28th to February 29th. I’ve never seen this construction before, and I find it quite genial!20140609_101721The date mechanism from a different angle.20140609_101803This is a wooden mock up of the very complex cam that drives the day length shutters. In the middle is the disc for the equator – it’s round, and day and night are the same length. Going left and right, the discs get more and more ex-centric, to cater for the short nights / long days and long night and short days close to the polar circle. The clock will work everywhere outside the two polar circles, and I don’t think that’s too much of a problem πŸ˜‰ You have to imagine that the space between the wooden discs is filled in, as this will be one smooth brass cam. George wants to have it printed with a 3D printer, and then cast it in brass.20140609_101818

Top view of the cam, with the 70 degrees north day/night length. This cam will turn once a year, and will be driven by the year wheel that we have seen earlier.

This has got to be one of the most ambitious clock projects ever, as this sort of mechanism has never been attempted before. I mean never! There are some clocks indicating day length, but they only work at one location.

The target date for finishing the clock is Summer 2015, and I can’t wait to see it. George and Cornelia intend to show it around a bit, so it might end up at an exhibition near you some day. There are also a couple of talks planned, so make sure to check on their web site in a year.

It’s been a long time that I have been that excited about something, and I can now relate to my 2 year old daughter when you mention the words “chocolate ice cream” πŸ˜‰





6 thoughts on “George & Cornelia DeFossard: The Solar Time Clock Project

  1. Ask them how much for a Antikythera mechanism clone πŸ˜‰

    It is indeed ambitious, but the end result will be a marvel!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.