Seth Thomas “Sussex” Adamantine Mantel Clock

I’ve always liked the appearance ¬†of these green and black Seth Thomas Adamantine mantel clocks, and this one is interesting in having the model name “Sussex” stenciled on the back. This clock has the 8-day movement with escapement in back, so it was made in 1901 or earlier. The case is 11 3/4 inches tall and 11 3/4 inches wide at the feet. The minute hand is 2 3/16 inches long.

Sold 3-3-02 E is written on the back of the clock, meaning that it was sold March 3, 1902.

See more photos.

Repair job 5855. New time click rivet, polished the pivots, installed 9 bushings, true the escape wheel teeth. The back escapement movement uses a strip recoil escapement requiring a small pendulum arc. The pendulum arc when running is much larger than the minimum arc (escape arc), so these clocks are very reliable even when slightly off-level. These movements have fairly thick mainsprings (around 0.018 inch) that are 11/16 inch wide rather than the standard 3/4 inch wide. If a mainspring does need replacing (it is best to keep the original springs) it is important to not use a spring that is too strong.

This example’s original mainsprings are the following sizes:

Time: 11/16 by 0.0175 inch

Strike: 11/16 by 0.018 inch.

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  1. I’ve seen this a few times, where the model name is stamped on the bottom of the clock near the date. I can’t explain why they wrote the model name on only a few clocks in this way.


  2. So I bought this clock at antique shop in California twenty years ago. It is a Seth Thomas 1909 Sussex, Green and black, paper dial, Width in accordance, Height slightly different. !0 and 3/4
    Two and 3/16 minute hand but what I find interesting is that Sussex is written on the bottom of clock upside down from the 1909. What is really strange is I am wondering, Did Seth Thomas ever hand sign a clock? Like on the label on the bottom back? There’s a signature there and it looks suspiciously like a Seth Thomas signature. Everything is definetly Seth Thomas. Stamped everywhere its suppose to be. No, it’s not a fake. But I sure am curious? Do you think it’s possible?
    Thanks, Judith Scott

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