# Digital sundials **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [June 23, 2008, 1:58pm UTC](https://boards.straightdope.com/t/digital-sundials/453911 "2008-06-23T13:58:26Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [June 23, 2008, 1:58pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/1 "2008-06-23T13:58:26Z")
Normal sundials are pretty neat, but I just discovered this [digital one](http://www.fransmaes.nl/genk/en/gk-zw08-e.htm). No moving parts, no electricity, but it displays the time, in digits, to within five minutes. How clever is that? You can even buy [windowsill versions](http://www.digitalsundial.com/product.html). ---
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [June 23, 2008, 2:12pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/2 "2008-06-23T14:12:53Z")
[QUOTE=Colophon] You can even buy [windowsill versions](http://www.digitalsundial.com/product.html). [/QUOTE] D’oh! I got all excited when I mesread that as “Windows version.” I’d get the windowsill version, except that 1. I don’t have true windowsills 2. I only get direct sunlight for about 2 hours per day 3. That’s when it’s not cloudy 4. 5/7 days I’m not there to enjoy it anyway ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [June 23, 2008, 2:13pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/3 "2008-06-23T14:13:12Z")
There have been various forms of digital sundials around for ages. Old ones used punched-out numbers. Newer ones use fiber optics. Several years ago I wanted to build one that used a solar cell to power (and to select) a digital display. Never got around to it. ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [June 23, 2008, 10:13pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/4 "2008-06-23T22:13:30Z")
That and this analog one are my favorites. [http://www.wsanford.com/~wsanford/exo/sundials/ca/claremont/index.html](http://www.wsanford.com/~wsanford/exo/sundials/ca/claremont/index.html) The analemmoid gnomon automatically takes into account the difference between civil time and solar time. Of course, ideally it should have a much thinner waist. ---
**Author:** ![Tripler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripler/32/21807_2.png) [@Tripler](https://boards.straightdope.com/u/Tripler)\ **Post date:** [June 23, 2008, 10:20pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/5 "2008-06-23T22:20:29Z")
Um, a question of part smartass, part honest ignorance: A ‘digital sundial’? Why not just wear a watch, or get an outdoor clock? I mean, the former is portable, and the latter works when the sun ain’t shinin’. Tripler What’s the appeal? ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [June 23, 2008, 10:29pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/6 "2008-06-23T22:29:02Z")
[QUOTE=Tripler] What’s the appeal? [/QUOTE] It’s for the gadget freak who has everything else. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [June 23, 2008, 11:15pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/7 "2008-06-23T23:15:02Z")
[QUOTE=Musicat] It’s for the gadget freak who has everything else. [/QUOTE] Yeah, and I find a certain aesthetic appeal in the amount of ingenuity that went into this thing, and the simple fact that it requires no energy source, no moving parts, just the motion of, y’know, the solar system and stuff. ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [June 24, 2008, 9:03pm UTC](https://boards.straightdope.com/t/digital-sundials/453911/8 "2008-06-24T21:03:07Z")
[QUOTE=Tripler] Um, a question of part smartass, part honest ignorance: A ‘digital sundial’? Why not just wear a watch, or get an outdoor clock? I mean, the former is portable, and the latter works when the sun ain’t shinin’. Tripler What’s the appeal? [/QUOTE] Regular sundials don’t work when the sun isn’t out, too. It’s just the appeal of not relying on electricity. And it sounds impossible or even oxymoronic. And it’s bloody ingenious. > **[Digital sundial](https://en.wikipedia.org/wiki/Digital_sundial#Towards_application)** > > A digital sundial is a clock that indicates the current time with numerals formed by the sunlight striking it. Like a classical sundial, the device contains no moving parts. It uses no electricity nor other manufactured sources of energy. The digital display changes as the sun advances in its daily course. > There are two basic types of digital sundials. One type uses optical waveguides, while the other is inspired by fractal geometry. > Sunlight enters into the device through a slit and moves as t... “The theorem was proved in 1987 by Kenneth Falconer. Four years later it was described in Scientific American by Ian Stewart. The first prototype of the device was constructed in 1994.” The Scientific American article was actually a “Mathematical Recreations” column. And the wiki article may be wrong because I believe there’s very little relation between the sundial’s method and the theoretical method. Also, the sundial is a novel application of existing simple methods.