Freshman Geometry Project - Astronomical Rings

The midterm exam for our daughter’s freshman geometry class is to make a mathematical instrument. She chose this traveller’s sundial (Equinoctial Dial) originally designed by an English mathematician, William Oughtred, in the early 17th century.

And it works! Adjust the center slider to the time of year. Point the device to true north along your latitude and it will tell you the time. Or, as our daughter pointed out, if you already know the time, you can use it to find your latitude.

She used proofgrade draft board to cut all the pieces. Hinged with brads, aluminum can slider (not cut with the forge).

Thank you Glowforge!



Ah this is great.


I love these kinds of projects! She did a great job on it. :grinning:


What a great project!!! Love it!

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Oh gosh, that is SO COOL! She is going to blow away the class and teacher with it.



Really Great!

This is fantastic! Traveller’s dials are really fun…

OR poor man’s compass to point North if you have a watch and know the time.
Looks very much like a nerd compass to me lol.

Very cool, great projects teach you more than one thing.


Well done!

This hits all the marks for me! :heart_eyes:
Beautiful and useable, old school tech that still works today, STEM education!
Nice job on this, I really need to make some more stuff like this!


Awesome project

Incredible project. Wish I had access to these tools when I was young.

Since not everyone has access to a laser, want to bet some school bans their use by students because not everyone would have the same advantage as the kid with one? Just like the old calculator and then computer and tablet wars in the schools.


I’m actually fine with not allowing outside tools and material. Adding constraints forces creativity. My son’s school does this. For example, in his engineering class all work must be done in class with the materials and tools available. Sometimes they’re only allowed to use drink straws or cardboard for the challenge given. Doesn’t prevent him from coming home and redesigning and building projects he wants to take further and, it’s forces him to solve problems in a different way than he would with the maker space that is our house.


I don’t mind that because it’s a special case where the instructor is providing a very specific learning experience. It’s the blanket prohibitions that are irksome - lowest common denominator rules. What if the town doesn’t have a library? Should kids be allowed to drive to the next town to look at books? There’s no real logical sense to the restrictions when they’re enacted and tend to be more along the lines of “my Johnny doesn’t have one of those so no one should be allowed to use one” vs a true value judgement of the usefulness of the tool or method in question and the “leg up” it gives to some kids.

I’ve always waited for someone to decide that smarter kids should have less time to take tests than slower kids - even the playing field because not everyone gets all the smart genes and it’s unfair to those that didn’t to have the smart kids finishing faster while others can’t finish at all. (Our school system has actually done the alternate - some kids are allowed far more time for tests as long as they can get someone to create a PEP that says they have a disability.)

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Wonderful environment :+1:

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Yes, In my geometry class we had a guaranteed “A” if we solved one of the problems he tossed out. Most of them were famous cases nobody has ever solved, but I saw a way to create an equilateral triangle of one square unit using only Euclidian methods.

After I proved it possible, two others also managed the easy “A”, but this is really Awesome! Even just drawing what the parts looked like would be possible for anyone no matter the special access, and that would be pretty awesome as well, making it real with a Glowforge would be gravy.


If you do it at high noon you will have the time (noon) and thus provide your latitude, a very important bit of info sailing a ship in uncharted or poorly charted seas. accurate longitude was a more difficult matter.

It appears that William Oughtred also invented the Slide rule as well

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