Location, Location, Location: Physical Geography of Eliera

General
1

Hello. Newbie here. Please pardon if I’m ignorantly posting in the wrong place.

In “Location, Location, Location”, the Taliar and Dalthiar shafts are said to reside at “the hub” on Upperside and Underside, respectively. The only other use of “hub” I know (in the context of flat world geography) is Discworld, so I am presuming that these lie at the centers of the respective sides.

My confusion began when referring to the tunnels of the Icemarch settlements which led away “to the south”.

At which point, my mental coordinate model for Elieran navigation destabilized.

On Discworld, “north” means radially inward - a synonym for “hubward”. Likewise, “south” is identical with “rimward”. The coordinate system for topology is smoothly convertible from the usual planetary arrangement by a simple scale transformation on the N-S axis; “squish” a Roundworld in the dimension of its spin axis and you have a Discworld. The spin axis does not change in this action; Discworld rotates in its plane, like a wheel, and does so to create seasons, not the day/night cycle. (Because Discworld’s thaumaturgical gravity field differs from Eliera’s, there is no habitable area on its Underside, and hence no Antarctic.)

The trouble arises because Eliera’s rotation axis is, per its ephemeris, tangential to its orbit, making it spin like a flipped coin rather than a wheel.

So what the heck do eldrae use for their cardinal directions??

The model I had been using up to this point assumed that “north” and “south” were the directions towards the axis, that “east” and “west” would be the directions in the surface quasi-plane perpendicular to the axis of rotation: the direction of the apparent motion of Lumenna and the “fixed” stars. But this would clash with the use of “south” in the Icemarch, which implies a rimward direction.

But Discworld’s polar coordinate system makes no sense either. Why would pre-Imperial eldrae naturally come up with such a system? The world is carefully engineered to look flat. Astronomy would be the first means of direction-finding even more than on Earth, and it would provide coordinates as I first described.

The coordinate of altitude, as defined by the Mystery Matter™‘s gravity field, is too obvious and imposed to be ignored. But what of the other two spatial referents needed? We have the polar system of hubward/rimward and deosil/widdershin, and the perpendicular (Euclidean or Cartesian, on Earth) system of rotation axis (along/against the orbital velocity vector) and equatorial (right- and left-handed).

So… how does a soph on Eliera orient themself?

2

North is most probably defined by spin. The sun rises in the east, and therefore north is to the left of sunrise and south to the right.
Either that or magnetically, in which case… I dunno, probably hubward/rimward? Which is, as discussed above, not sensible in this case.

3

This is, as in so many cases when things are complex, complicated by there being two different widespread coordinate systems in use.

“Global” or “geographer’s” coordinates are a polar coordinate system; this is the highly official one devised and used by the Imperial Society of Geography, Cartography, and Terrestrial Navigation to locate things on a worldwide scale. The pole is the surprisingly-not-the-spin-axis (i.e., the center of the Talíär shaft) and the meridian is obtained by drawing a line from there through the peak of the Imperial Mountain. In this paradigm, the directions are “hubward”, “rimward”, “runward” and “beatward”. The latter two refer to the prevailing direction of the trade winds (which spiral from hub to rim and back) rather than spin around that axis, of which there isn’t any. Meanwhile, although not all that often used, absolute altitudes are measured from the midpoint of the world and are negative on the Underside. Don’t ask about the edges.

Meanwhile, “local”, or “cartographer’s” coordinates, the traditional system, are a Cartesian coordinate system (because that maps so well and conveniently onto a flat plane). The axes are defined mostly astronomically - the primary axis is aligned “riseward”-“fallward”, and the other is defined by perpendicularity to it (“trackward”, and “courseward”, from orbital direction, once the astronomers weighed in), for which we can substitute “east”, “west”, “south”, and “north” in translation. On the occasion when someone wants to put actual coordinates on those axes and are making a global map, the traditional zero-zero point is the Zero Milestone in the capital.

(Note, of course, that on Underside riseward/east and fallward/west are reversed from what they are on Upperside, but the other two directions are not. This is one of the more minor reasons that it isn’t considered the global system.)

So those tunnels in the Icemarch do run southward (and a smidge westerly) from the Talíär towards the Frozen Gates and Ajcleft, but they also run rimward (and a touch beatward). It’s all in your point of view.

(Side note: Eliéra does have a magnetic field, but its shape makes it a lot less useful for navigation with a standard magnetic compass; something like Dune’s paracompass for navigating by local magnetic anomalies would be much better. In practice, early land navigation involved a lot more sun-sights and star-sights than one might expect.)

4

As usual, I tip my hat to your worldbuilding thoroughness. However, I fear questions still remain…

I’m confused again, because not long afterwards you state:

I’m pretty sure the former is a typo, but…

I presume Underside had some other tradition? Without a truly global view — meaning orbit, which was harder than usual — I’d guess surveying over the Edge would be, um, problematic.

Which is why I think one question about the Edge would be appropriate: what about the North and South (or Course and Track) Poles? They’re the only spots on Eliera that get anything even close to an even barbecue roll, and therefore would (my intuition says) be the places where the Edgestorms would be least fierce. Therefore they would be the logical places for the still world-bound eldrae to attempt to cross the Edge — unless the Precursors were thoughtful enough to design sheltered land passages in advance.

I’m guessing upperward and underward would best apply there…

5

I’m pretty sure the former is a typo

It was. I fix.

6

I presume Underside had some other tradition?

Well, originally there were lots of local traditions. The Empire did a whole lot of standardization of maps and meridians, the way that expanding Empires tend to.

The Edgestorm isn’t proximately caused by the flip (only rather indirectly via ongoing effects on trade wind patterns); rather, it’s the ongoing effect of the outermost cells of each side’s atmospheric circulation bashing into each other and whipping up perfect storm conditions, so there aren’t really any weaker spots - permanent weaker spots - in the stormwall.

Such contact as there was between Upperside and Underside before the construction of the World Shafts was notably sporadic, based on one broken land bridge and a scattering of sea captains with sturdy ships and no discernable sense of self-preservation.

7

So there was a land bridge, just one that only sophs with the self-preservation instincts of a first-in scout would venture to cross.

But the mention of the World Shafts brings up a related pair of questions:

  1. How do you dig World Shafts that you are sure won’t emerge in an ocean? Roundworld’s geography would be very unforgiving to such an endeavor even if transferred to a shape like Eliera’s.

  2. How in all the fifty eikones did they get past the Mystery Matter™ with Steam Age tech???

8

Maybe they weren’t sure, so they built it with a self-lengthening caisson just in case.

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9

As for point 2, to paraphrase Howard Tayler: “Building tunnels by destroying artifacts is a time-honored atrocity”

10

How do you dig World Shafts that you are sure won’t emerge in an ocean?

You don’t. Be vewy, vewy careful as you dig “up”…

How in all the fifty eikones did they get past the Mystery Matter™ with Steam Age tech?

Turns out they didn’t have to. To clarify that, I should say that they already had some idea where to dig - gravimetric surveys had found three spots with otherwise inexplicable “dimples” in the even gravitational field, in a suspiciously equilateral triangle centered on the hub. Potential passages through the Mystery Matter weren’t the only possibility, of course - although they were a leading one - but even if the World Shaft project didn’t work out, they’d certainly find something interesting down there…

(As for why they exist in the first place? The Precursors only know for certain, but one wit did point out that turning even a planetary core-sized object on a lathe would leave some tool marks…)

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11

Oh, I’m sure they would have found something interesting no matter what. But when you live on an incredibly complex artificial construct that requires ontotechnological manipulations merely to attain structural stability, interesting might just be something you regret finding.

Briefly.

As you said above: be vewy, vewy careful…

Normally that would merely be a chuckle, but with the Precursors’ capabilities, you can’t be entirely sure that’s not the correct answer after all…

12

Actually, now I’m curious how they dealt with the excavation tails as the gravity flipped past the mid-plane of Eliera.

13

With machinery .

(Ad-hoc invented machinery, to be specific.)

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14

Machinery that worked by doing things? Because of reasons? :face_with_monocle::crazy_face:

15

Actually in hindsight it’s pretty easy, you just let the tails fall away and they’ll zoom through the tunnel to the equivalent depth on the other side; then all you need is a catcher and the same hauling methods you used for the downward leg of the tunnel.

16

Pretty sure you want more than just that, or else it’s going to be quite rough on any equipment – or personnel – between positive and negative [CURRENT_ABSOLUTE_ELEVATION]… but yes, any solution is certainly going to make the [onto-manipulated] gravity gradients work in your favor.

The same principle would eventually be used for the eventual transport system itself, using the entire length of the World Shaft. That machinery would perforce be less ad hoc. No sense in working hard when the Precursors have literally done the heavy lifting for you…

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17

Bucket elevator, only the buckets have lids and are invertible. As the bucket crosses the midpoint, it swings around, and the other buckets you put in act as counterweight to lift it again.

18

Paternosters, except now twice as confusing!