You could also use a vertically-hanging weight and then measure the angle of the sun in relation to that vertical line to determine latitude. While the sun-shadow compass realised on a standardised length of the stick to make accurate calculations, this method relies on accurate and equal divisions of a circle, so they both have some drawbacks. Actually, thinking about it, does the sun-shadow compass need to be a standardised length? If you measure the length of the shadow, then the ratio of that length and the length of the stick would end up equal for any length stick at the same latitude. As Podcreature points out, however, the only problem is making sure it's exactly vertical to the ground, but several methods could be used to fix that issue.
As for determining longitude, I think your best best would probably be to use a magnetic compass. While magnetic north might not line up with axial north, the position of magnetic north is relatively stable over the space of centuries.
If you take the measurement of the suns position in the sky in relation to magnetic north, then you should be able to determine longitude (if the sun is directly behind you as you point the compass toward north, then you're north, while the sun being directly ahead of you would put you in the south while the sun being directly above would put you at the magnetic equator. If you're on the equator, but then as you move east the sun should the sun should be directly to your left while it should be directly to your right as you move west. Positions in the north west would then have the sun be behind you and to the right and so on and so on. You should, then be able to work out your exact position from there using either the sun-show compass or the weight-angle compass. I think
Yes. Determining the compass bearing so it lines up correctly was bugging me. I had the same thought about the magnetic pole but I like your idea of the hanging weight on a line as a more accurate vertical tool.
Originally Posted by sangi39
I've really enjoyed all the brainstorming about navigation. It'll also be very helpful later, I'll have to credit you guys somehow if I use your sun-dial tool ideas, lol.
So, jumping into my update... I did a little more research on the "lobster" shape and it -does- make sense... when we see a world without day or night we automatically think it doesn't turn, but as I figured out and mentioned earlier in reference to poles and such, that it does. That rotation, however slow, does create a current. Apparently we could find tide-locked worlds that are either eyeball shaped or lobster shaped, so I guess it works that mine is a bit of an oval... either way, I figure that where it's at in the goldilock's zone, means that where it's dark, it's basically snowy. But where the warm air drags across the planet it's a habitably snowy cold until you get further around the planet.
In light of this understanding I have reworked my map, and I've taken time to think about the ecology and oxygen producing bacteria that don't photosynthesize and came up with some new and unique colors for the seas and shores in the twilight zones.
There's still stuff to fix, like inconsistent borders, the wrong plant growth in certain elevations and zones, and I will need to painsteakingly hand-draw the rivers since I didn't figure out how to generate a river mask thing in Wilbur before diving into this... eeehhh...
Edit: I welcome suggestions for styles and themes that go along with functionality as a map for a story or RPG. ..As in I'm trying to decide what do with it at this point.
Last edited by Podcreature; 05-04-2014 at 08:02 AM.
Reason: updated image, fixed typo
I know this is just a TV show, but in Vikings they do this by letting the sun-compass float in a bucket of water so that its always level to the plane of gravity. (I think)
Originally Posted by sangi39
Last edited by AlexSchacher; 05-03-2014 at 11:12 PM.
That's exactly what I was saying like, five or something posts back, lol... not about Vikings, but a sun dial on a plate that's sitting on water. I wonder if there's a way it could be made to fit on a person's wrist if the craftsmanship was advanced enough. Like in a glass bauble or disk. It would need to be oil in that case so it wouldn't evaporate and fog the glass.
Originally Posted by AlexSchacher
Hmmm. How about using mercury? Far more stable than water. Maybe the plate could be magnetic and point to North to mark your bearings, then read the shadow length.
Originally Posted by Podcreature
I think a wrist version would be too small for serious navigation. You would need a much larger plate to get an accurate distance reading.
For that I would think loose gimbals on a tripod would keep the plate level while a floating compass on mercury will give you a bearing to adjust the plate to read the shadow. The plate would be engraved as accurately as the technology of the people will allow.
It would be large, maybe 1 foot across to be accurate. This would be used by explorers, merchants and the military. Casual travelers usually would stay on known paths and not go very far from home so the use of a personal compass would be more of a rich man's toy or jewelry.
Edit: Wait a min! I keep forgetting about spirit levels! You don't need to float it. Just place a bubble in a fluid in the center of the compass and you can adjust it till it becomes level.
Last edited by Nexis; 05-04-2014 at 01:51 PM.
I'm in agreement with all of that! I'm sure natives figured out how to mine mercury as early as humans ever did. I totally agree with the need for larger tools for precise navigating, was already thinking that to myself too... Some trips might not need as much so varying levels of size and quality would likely be seen. For any version that did use a glass bauble and an air bubble, would water scatter light and dim or affect the shadow? I guess that could be calculated for... Though convenient versions might still use a bed of oil or mercury, just because trying to hold it level yourself could be a little annoying, since it could be a big deal if you're off even a little bit.
Originally Posted by Nexis
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