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Seth Thomas Watch Specifics
Unique Designs
Seth Thomas watches, like most brands, had many components in common and a few that were unique to their designs. This page is for the nuts and bolts of the factory models, from plate finishes and balance staffs, to regulator styles and the meaning of the word Adjusted.
Don't miss the section at the bottom on identifying Swiss fakes.
Plate Layouts
Full Plate
Bridge Plate
Full Plate
The Model 5 was the factory's sole full plate design, where the only visible component was the balance wheel.
3/4 Plate
Bridge Plate
Full Plate
Every other model was a variation of the 3/4 plate, where the balance wheel was between the upper and lower plates.
Bridge Plate
Bridge Plate
Bridge Plate
The only bridge design was the 12-size Model 23, which had separate bridges for the pallet, and the escape and 4th wheels.
Plate Finishes
Gilt
Nickel
Nickel
Gilt was the earliest finish, used on the Model 1, and continued on every 18-size model. It was also used on the 6-size Model 14.
Nickel
Nickel
Nickel
The earliest known nickel finishes were used on the Model 2, and were used on every model except for the gilt Models 1 and 4.
Flashed Gilt
Flashed gilt was the rarest plate finish, reported in small runs of the Model 5, and on individual watches in Models 1 and 2.
Two-Tone
Nearly every model had at least some two-tone finishes, except for the gilt Models 1 and 4, and the nickel Centennial Series.
The Mechanicals
Balance Staffs
Single Roller
The roller table mounts the roller jewel and meshes with the guide pin mounted on the end of pallet fork via a crescent-shaped cutout milled in its edge which prevents the pallet from drifting. The overwhelming majority of Seth Thomas watches had single-roller escapements.
Double Roller
Overbanking occurs when the roller jewel becomes misaligned with the pallet cup, which was possible with the single roller design. The double roller was developed to eliminate this, using a smaller lower table with an indent to mesh with a horizontal guard pin, pictured here. The only watches to be fitted with a double roller were the final runs of Model 5s.
The Hairsprings
Flat Hairsprings
The hairspring is the balance wheel's rebound mechanism, oscillating in and out five times every second. The coils of a flat spring all lay on the same plane, anchored at either end by the collet, a brass split-ring that grips the balance staff, and the stud at the tail. The factory installed flat hairsprings on all of its early and lower grades.
Breguet Hairsprings
Prussian watchmaker Abraham Breguet is credited for inventing the overcoil hairspring, which put the final turn of the hairspring above the other coils, minimizing lateral friction to the balance staff. Seth Thomas used the Breguet hairspring on its higher and later grades, including the New Eagle Series, the Models 5, 17, and 19 to 24.
Mainsprings and Barrels
T-End Springs
Seth Thomas exclusively used a T-end mainspring in all of their models.
Going Barrel
A standard going barrel was used on all of the models, unjeweled with a snap-on lid, pictured here.
Motor Barrel
The only known instance of a motor barrel is on the 19-jewel Grade 262.
Gear Train Speeds
Slow (Coarse) Train
Roughly a sixth of the Model 1s ran on a "slow" gear train, designed for precisely 4.5 beats-per-second (BPS). Multiplying 4.5 BPS by 3,600 seconds in an hour returns 16,200 beats-per-hour, or BPH.
Quick Train
On all later models the balance rate rose to 18,000 BPH to increase accuracy. That figure translates to 432,000 beats per day, 3,024,000 per week, 12,960,000 per month, and 157,680,000 per year.
The Regulator Styles
Model 1
Models 2 and 3
Models 2 and 3
A simple whip with a variant of the Reed gooseneck on the later and higher grades.
Models 2 and 3
Models 2 and 3
Models 2 and 3
A simple whip with or without a variant of the Reed gooseneck in mirror image.
Model 4
Models 2 and 3
Model 4
A mirror image of the Model 1 whip but without the Reed gooseneck spring.
Model 5
Model 5 Railway
Model 4
An inboard or outboard whip, with or without a variant of the Reed gooseneck.
Model 5 Railway
Model 5 Railway
Model 5 Railway
A star prototype, found only on the Model 5 Railway and possibly on the 17J Model 21.
Models 6 to 9
Model 5 Railway
Model 5 Railway
A simple whip with or without a variant of the Reed gooseneck in mirror image.
Models 12 and 13
Models 12 and 13
Models 12 and 13
A whip with or without a variant of the Reed gooseneck spring in mirror image.
Model 14
Models 12 and 13
Models 12 and 13
A simple left-facing whip with no Reed gooseneck for flat or Breguet hairspring.
Models 15 to 20
Models 12 and 13
Models 21 and 22
A simple left-facing whip with no Reed gooseneck for flat or Breguet hairspring.
Models 21 and 22
Models 21 and 22
Models 21 and 22
A simple right-facing whip with no Reed gooseneck for flat or Breguet hairspring.
Model 23
Models 21 and 22
Model 23
A simple whip with or without a miniature variant of the Reed gooseneck spring.
Model 24
Models 21 and 22
Model 23
A simple right-facing whip with no Reed gooseneck for flat-only hairspring.
The Meaning of Adjusted
Most of the surviving information on Seth Thomas watches is ambiguous at best, and to date no paper of any kind has been reported to define what the factory meant by "Adjusted", though that word was stamped seemingly at random on several models.
Adjusted
Before the turn of the century an "adjusted" watch was taken to mean that it had been fine-tuned for the three most common positions of dial up, dial down, and pendant up, and for swings in temperature. Since there is no mechanical difference between an adjusted watch and an un-adjusted one, it could have been a simple marketing trick for higher prices. Both watches can certainly attain identical accuracy.
Adjusted to Temperature & Position
If the word Adjusted meant that a watch had been fine-tuned for temperature changes and the three most common positions, then there was clearly no need to spell it out, but the Grades 506 and 508 both specified these extra calibrations, though it's not clear which positions were being referred to. Since the Henry Molineux grade was simply marked Adjusted, it's possible that the Grades 506 and 508 would've superseded the Molineux in the same jewel count.
3 Positions
Again, if the word Adjusted meant that a watch had been fine-tuned for changes in temperature changes and the three most common positions, then clearly there was no need to spell it out. The 18-size Grade 282 and the 12-size Grade 28 did just that, with the 282 preceding the 28 by well over a decade. The earliest known 282 dates from roughly 1897, well before the new railroad criteria.
5 Positions
After 1907, one industry requirement was the number of positions to which a watch was adjusted had to be clearly marked on the upper plate. Five positions refer to dial up, dial down, pendant left, pendant right, and pendant up. The only Seth Thomas watch to carry these markings was the 17-jewel Grade 382, which appeared in the second and fifth (final) serial number block, and since it was lever-set it was considered railroad grade by some accounts.
5 Positions and Temperature
Since the word Adjusted was taken to mean that a given watch was compensated for changes in temperature, it seems an unnecessary step to mill that on its plates. The only watches to carry this unique marking was the final run of the 21-jewel Grade 260 and last three runs of the 21 and 25-jewel Maiden Lane.
6 Positions
Six positions could also mean nine adjustments - the six positional ones, plus isochronism, plus one each for hot and cold. It was the highest marking grade and only the 21-jewel Grade 260 and the 25-jewel Maiden Lane carried them, and both were railroad grade.
Swiss Fakes
The Cases
From the outside, Swiss reproduction cases are meant to look antique but have too little mileage on them to be a century old. They have multiple motifs vying for space, such as the apron-wearing blacksmith holding a waterwheel on this shoulder while standing next to his anvil and a leg vise. Behind him is an arched bridge, telegraph lines, and factory chimneys belching smoke.
The Dials
There are several immediate signs that the dials on Swiss fakes are not from the railroad era. They are usually marked "Swiss-Made" at the bottom of the dial, have a registered trademark (®) next to the signature, and they have a sweep center hand, something that genuine Seth Thomas pocket watches never had.
The Movements
Like the dial, the movement is also marked Swiss, and if that weren't enough of a tip-off, all the parts are stamped with sharp edges, rivets have clearly been used in places, and none of the surfaces are brushed, finished, or carry any kind of pattern.
Please do not write asking what these are worth.
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