Seventeen Jewels and One Hairline Fracture
Seventeen jewels. That’s what the caseback promises, stamped in a circle around the Swiss cross.
The antique market in Old Strathcona yielded this: a 1940s dress watch, gold-filled case, crystal clouded but intact. The seller called it “non-running,” which is the polite term for “I don’t know what’s wrong and I’m not curious enough to find out.” Twenty dollars. The movement rattled slightly when I shook it, which either meant loose components or a broken mainspring. Either way: disassembly material.
I’ve been thinking about this since February, since the music box cylinder disaster taught me that Victorian precision mechanisms punish impatience in ways that software never does. A bug in code waits patiently for you to find it. A bug in brass screams across your workbench and wedges itself under the refrigerator.
The caseback came off with a gentle twist—bayonet mount, not screw-down. Inside: rose gold Geneva stripes on the bridges, blued screws, and the balance wheel sitting motionless in its jeweled cradle. No ticking. The hairspring coiled correctly, no visible kinks, but nothing moved when I nudged the crown.
What “17 Jewels” Actually Means
I’d read about this but never counted. Jewel bearings reduce friction where metal pivots spin in metal plates—sapphire-on-steel friction is about one-third that of brass-on-steel, which matters when you’re asking components to turn 432,000 times per day. The seventeen-jewel configuration breaks down like this: two cap jewels and two pivot jewels for the balance wheel, plus the impulse jewel that contacts the pallet fork. Two pallet jewels (the ones that actually touch the escape wheel teeth) and two pivot jewels for the pallet fork itself. Then two pivot jewels each for the escape wheel, fourth wheel, third wheel, and centre wheel.
I counted them. Seventeen. Each one a synthetic ruby pressed into a brass setting, each one doing a job that doesn’t stop until the mainspring runs dry.
The jewels weren’t the problem. Under the loupe, every bearing looked clean and properly seated. The problem was the balance wheel, which should oscillate freely but sat frozen. I needed to disassemble the escapement to understand why.
The Mainspring Let-Down
This time I own the correct tool. A mainspring let-down key that fits the winding arbor, allowing controlled release of stored energy before disassembly. The Waltham disaster—click spring launched into dimensional exile—had been instructive.
The key engaged. I turned slowly, counterclockwise, thumb on the crown to control the release. Nothing happened. No tension. The mainspring was either already unwound or broken.
Removing the barrel bridge revealed the answer: the mainspring had set. “Set” is horological jargon for a spring that’s been wound tight for so long that it’s lost elasticity—it remembers its coiled position and won’t unfurl properly. The outer coils were welded to the barrel wall by dried lubricant. Decades of sitting, spring wound, owner deceased, movement forgotten in a drawer somewhere.
The spring itself measured about 25 centimetres uncoiled, 0.12 mm thick. Blued carbon steel, pre-war manufacture, before the white-metal alloys that resist setting. Even if I cleaned the barrel and freed the spring, it would never deliver consistent torque again. Replacement springs exist, calibrated by height, width, and length. Finding the right one requires knowing the movement caliber.
What the Caseback Didn’t Say
Swiss movements from this era often don’t have caliber numbers—just the manufacturer’s name and jewel count. Under the balance cock, I found the letters “AS” and a three-digit number: 984. A.Schild, one of the big ébauche manufacturers. The 984 was their workhorse caliber, ten ligne diameter, used in countless mid-century dress watches.
The ébauche system itself is fascinating—the Swiss watchmaking industry fragmented into specialists, with ébauche manufacturers producing raw movements and finishing houses adding the dials, hands, and branding. This watch is anonymous in a sense: the case is American, the movement is Swiss, and whoever sold it originally added their name to the dial and nothing else.
The pallet fork came out cleanly. Two jewels, as promised, their synthetic ruby faces still smooth after eighty years. The escape wheel followed, and I could finally see why the balance wheel wasn’t moving: the impulse jewel—the tiny synthetic ruby pin on the balance roller that receives the push from the pallet fork—was cracked. Hairline fracture, invisible without magnification, but enough to jam the fork’s action.
A cracked impulse jewel is fixable. It’s a standard replacement part for common calibers. The mainspring is fixable too. What’s not fixable is the expectation I had, driving home from the market, that I’d have a running watch by nightfall.
What’s Running Instead
The movement sits in a parts tray, disassembled correctly this time. No springs escaped. No components lost. The escapement is in one tray, the gear train in another, the mainspring barrel in a third. I photographed each layer before removal, which is what you’re supposed to do but what I skipped last time in the enthusiasm of “just getting it open.”
Tomorrow I’ll order the mainspring and impulse jewel. The springs come from suppliers in Germany; the jewels from a catalogue organized by caliber number. While I wait, the movement will sit, each component labeled, and I’ll study the gear ratios—how 18,000 beats per hour translates through the wheel train into one rotation of the minute hand per hour, one rotation of the hour hand per twelve.
The ticking sound that watches make? That’s the escapement working. Each tick is the pallet fork releasing one tooth of the escape wheel, one unit of energy escaping from the mainspring into motion. The word escapement isn’t metaphor—it’s what the mechanism literally does. It lets time escape, tooth by tooth, into the world.
Seventeen jewels, eighty years of stillness, one cracked ruby smaller than a sesame seed. Twenty dollars at an antique market. I’m not sure what I expected, but this is better: a mystery with components I can identify and a failure I can repair.