The stalled orrery · Velstraven

A major room of chapter 3. When you walk in, the room card reads: The orrery rings stand out of true, so the locking bar cannot pass through them.

Narrated walkthrough

The stalled orrery from its entrance — The stalled orrery: how to solve it

Getting there

Chapter 3, third upper floor, in the dome at the top of the winding stair past the counterweight lift. Its west door leads to the Reverse-view alcove, its east door to the Lens-cleaning room. Solving it raises the service gate east of the Lens-cleaning room, toward chapter 4.

What is wrong

"The orrery rings stand out of true, so the locking bar cannot pass through them." A brass strap couples the outer and middle rings to one drive sleeve, so they turn together. Each ring must reach a different detent: outer 1, middle 2, inner 3. The room is dim.

What you can work

Brake: The mechanism brake on the drive sleeve, on at the start. Handwheel on the left.
Crank: Hand crank on the right. Each turn advances the coupled outer and middle rings one detent.
Outer pad: A service pad touching the outer ring's rim.
Clutch: The slip clutch between the outer and middle rings.
Drive: A thermal piston behind the crank that can repeat a stroke it has been shown.
Outer ring / Middle ring / Inner ring: The three brass rings, high overhead. Each carries one curve of the figure and a slot for the bar.
Wheel 0 / Wheel 1 / Wheel 2: Service handwheels geared to the outer, middle and inner ring. Each turns its ring one detent, but only when nothing couples it.
Strap: The thin drive strap coupling the sleeve to the outer rings, with a stone shield behind it.
Bar: The manual locking bar at the front. It passes only through three slots in one line.
Basin: A dry basin on the floor. Redirect light here shows the mural; a reading aid only.
Face: The reference mural under the gallery, showing the whole figure. Soot dims it; Handle or Cleanse surface cleans it.
Reading lamp: Optional light to read the room by: Handle toggles it, Heat lights it, Supply liquid douses it, Place light roots a lasting flame blossom in its cup. It works none of the room's fittings.
Reading shutter: Optional: Handle or Orient opens a high window for daylight from a second angle. It works none of the room's fittings.

Solution

A nudge

While the brake holds, the drive sleeve cannot move and the crank does nothing.

The full solution

Handle the Brake to release it.
While the brake holds, the drive sleeve cannot move and the crank does nothing.
What you see: "The mechanism brake changes engagement." The brake reads "The brake is off; the drive sleeve can turn."
Handle the Crank once.
The strap carries the outer and middle rings together, one detent each. That puts the outer ring on its mark.
What you see: "The crank demonstrates the coupled ring motion." The room card counts "the outer ring stands true".
Aim at the Outer pad and cast Anchor (Growth, Growth, Water).
A root cuff holds the outer rim to the fixed pad, so the next stroke cannot move it.
What you see: "A root cuff holds the rim at its contacting service pad."
Handle the Clutch.
With the outer rim held and the slip clutch engaged, the drive turns the middle ring on its own.
What you see: "The differential clutch changes which ring can slip."
Cast Repeat motion (Fire, Will, Will) on the Drive, let it make one stroke, then dismiss it (middle mouse button, or pad Circle/B, with the Drive targeted).
The piston repeats the crank stroke every 2 seconds. One stroke takes the middle ring from 1 to 2. Left running, it keeps turning the ring past its mark.
What you see: "The thermal piston repeats the demonstrated crank stroke." The card adds "the middle ring stands true".
Aim at the Inner ring and cast Orient (Water, Will, Will) three times.
The inner ring is never coupled and needs three detents.
What you see: "The supported ring turns to its next service detent." three times, then "the inner ring stands true".
Handle the Bar.
All three slots now stand in one line.
What you see: "The bar passes through all three aligned slots." then "The stalled orrery settled."

Other ways that work

No Repeat motion needed: after Anchor and the Clutch, just Handle the Crank a second time. With the outer rim held, a hand stroke moves only the middle ring.
Cut the coupling: with the Brake still ON, cast Sever (Fire, Fire, Fire) on the Strap ("The thin drive strap parts; the ring bearings remain supported."). Then Handle Wheel 0 once, Wheel 1 twice and Wheel 2 three times, and Handle the Bar. This uses one spell and is the fastest route.
Handle Wheel 2 three times instead of casting Orient on the inner ring.
Reading aids, never required: Handle the Face (or cast Cleanse surface on it) to wipe the soot off the mural; Redirect light (Wind, Wind, Water) on the Basin shows the lit mural beside the rings; light the Reading lamp.

Watch for

While the strap couples them, Wheel 0 and Wheel 1 refuse: "The ring does not turn on its own while the sleeve couples it; the crank drives the coupled rings together."
Sever only works with the brake on: "The moving drive strap cannot be cut safely against its backing."
Repeat motion needs a stroke to copy, so turn the crank by hand first: "The thermal drive needs a demonstrated stroke." The Drive is behind the crank, so step round to its side to aim at it.
The rings hang about 3.4 m up, out of hand reach. Turn them with Orient from below or with the handwheels.
Each ring's line says whether it is right: "Its curve meets the figure and its bar slot stands in line."
Overshooting is not a disaster. Every ring wraps round after four detents.

If it goes wrong

There is no failed state. A refused bar just says "At least one ring slot obstructs the through-bar." Check each ring's line.
Hold R for one second ("Keep holding to restart from the room's autosave"), or use the pause door "Restart from autosave", to put the room back as it was when you walked in: "Automatic room-entry save restored." Rooms you settled earlier stay settled.

Achievements here

The Orrery Turns Again: Solve the stalled orrery.
Clockwork Hurry: Solve within 180 seconds of entering the dome (the clock starts as you step in from the stair). Bind Sever before you climb up. Leave the brake on, Sever the Strap, then Wheel 0 ×1, Wheel 1 ×2, Wheel 2 ×3 and the Bar. That is one cast and seven presses, well inside the limit. The 180-second limit is provisional and may change.
Light in the Dark: Light in the Dark: cast Place light (Fire, Growth, Growth) at the Reading lamp here ("A flame blossom roots in the reading-lamp soil cup."). Any Place light cast in this room that takes hold counts. The dark frieze in chapter 1 also counts.

Spells used

Anchor, Repeat motion, Orient, Sever, Cleanse surface, Redirect light, Place light.