How to Date a Seth Thomas Clock

Determine the style of clock in your possession. Seth Thomas clocks manufactured during the late 1700s through the early 1800s included wooden movement tall clocks and shelf clocks. In the mid-1800s, brass movement clocks cased in O.G. cases began to replace the wooden movement clocks.

Check the back and bottom of the clock case for a date stamp. Between 1881 and 1918, many Seth Thomas clocks were date stamped with both the year and month they were crafted.

Note that date stamps were custom crafted by labeling the year backwards and number the months by the first twelve letters of the alphabet, A-L. If your clock has the numbers 7191 G stamped on the back, then your clock was manufactured in July of 1917.

Date the clock by its purpose and origin. Seth Thomas manufactured a number of clocks for several clients, including a line of specialized military clocks during WWII. Many of these clocks were designed for use on Naval ships, so if you have a military style Seth Thomas clock in your possession, you can generally date it from the WWII period.

Visit an antique appraiser who specializes in clocks if there is no date stamp on your clock, or you're not sure about the style of clock you own. Based on the material and make of the clock, an appraiser will be able to help you narrow down the manufacture date of your Seth Thomas clock.

Check out books and images of different styles of Seth Thomas clocks manufactured throughout the years, and identify styles similar to the clock in your collection. This may help you narrow down the time period your clock was created.