This Seth Thomas Adamantine mantel clock is dated June 1918 on the bottom of the case (date code 81F, where F represents the month, and 81 are the last two digits of the year reversed). I’ve seen many examples on earlier clocks where the date code has all 4 digits of the year, but this is the first time I’ve seen just 2 digits.

This later example of the Adamantine case has a simplified design with no pillars or Lion’s heads, and the dial is painted metal. See Seth Thomas Adele Adamantine Mantel Clock for an example of the earlier case design.

Case height 10 inches, width 12.5 inches, minute hand length 2 9/32 inches. The pendulum bob is lead with a brass cover on one side, weighs 5.4 ounces and is 45 mm in diameter.

The original mainsprings have the following measurements:

Time: 3/4 inch wide by 0.0175 inch thick

Strike: 3/4 inch wide by 0.0171 inch thick.

See more photos.

Job 5577. I did limited repair on the movement: cleaning, polished the worst pivots, installed 8 bushings (correcting 3 that were previously installed off-center), and tightened the strike click rivet.

Related posts:

1. Date Codes on Late 1940s Seth Thomas Electric Clocks
2. Seth Thomas Mahogany Adamantine Mantel Clock
3. Seth Thomas “Adele” Adamantine Mantel Clock
4. Seth Thomas Red & Black Adamantine Mantel Clock
5. Seth Thomas Green and Black Adamantine Mantel Clock, Rear Escapement

The model name of this Adamantine mantel clock is “Adele”. When it was new the case was deep red, but it has faded to red-orange. The clock is 11 1/2 inches tall and 12 1/2 inches wide at the feet. The minute hand is 2 1/8 inches long.

The movement is labeled “4 1/2″ on the back, but it is the same as the No. 89 movement. The name “Adele” is stamped in ink on the bottom of the case. There may be a date code as well, but it is very faint.

See more photos.

Repair job 5564. This clock has its  original mainsprings marked Seth Thomas. They are both 3/4 inches wide and 0.0175 inch thick.

Related posts:

1. Seth Thomas Red & Black Adamantine Mantel Clock
2. Seth Thomas Mahogany Adamantine Mantel Clock
3. Seth Thomas Mahogany Adamantine Mantel Clock
4. Seth Thomas Green and Black Adamantine Mantel Clock, Rear Escapement
5. Seth Thomas “Adamantine” Mantel Clock with “Ding Dong” Strike