Jerome used a variety of stamps on his movements over time, and for periods he used no maker’s stamp. Examples of the types of stamps he used are shown below, along with a description of the movement types they’re found on, as well as approximate timeframes. The earliest of his movements (types 1.111-1.114) contained no maker’s stamp. Stamps first appeared on type 1.211 movements.
Type 1.211 movement, with serial number stamp “NO. 5158.” On 30-hr movements, I’ve seen serial numbers ranging from the low 3000s to just over 10000. 8-day movements of the same period appear to have serial numbers lower than 1000. Serial numbers appear to have been used around 1840-1841.
“C. JEROME” stamp on an early type 1.311 movement. This stamp also appears on late type 1.211 movements. This stamp probably dates to 1842-1843. I do not believe a maker’s stamp was used for a period on movements after the end of the serial number stamps and before the “C. JEROME” stamp was introduced.
The standard Bristol stamp: “MADE BY C. JEROME/BRISTOL CONN/USA.” This stamp can be found on type 1.311 and 1.32 movements from around 1843 to 1845. The earlier ones would be found in Bristol-labeled clocks, whereas the ones from 1844-1845 would be in New Haven-labeled clocks. Some type 1.311 movements from this period do not have a maker’s stamp. There could have been a short period between the “C. JEROME” and the standard Bristol stamp when a stamp was not used. It’s also possible that some of these unstamped movements represent ones that were salvaged from the April 1845 Bristol fire that destroyed most of Jerome’s factory buildings there.
This stamp, stating “MADE BY C. JEROME/USA”, was probably used immediately after the fire in Bristol and before a New Haven stamp was made. Careful inspection shows that it is the same stamp as the standard Bristol stamp, except that the “BRISTOL CONN” line was filed off of the stamp so that it did not make an impression. Very few movements with this stamp exist, and they all appear to be the unusual type 1.81 movements, which are believed to be made of a combination of parts salvaged from the fire, as well as newly manufactured parts in New Haven and perhaps even some parts bought from other makers. These stamps likely date to 1845. For more on this movement and stamp, see NAWCC Bull. 339 (Aug 2002), p. 497-499.
The standard New Haven stamp: “CHAUNCEY JEROME/NEW HAVEN CONN/USA.” This stamp is found on type 1.311, 1.312, and 1.314 movements and was the stamp used from around 1845 to 1856, when Jerome went bankrupt. There may have been a short period before this stamp was introduced when no stamp was used. Some type 1.314 movements made shortly before Jerome’s bankruptcy also have no stamp.
The stamp, “C. JEROME”, was used by Jerome after he went bankrupt and worked for Benedict & Burnham and the Waterbury Clock Co. during 1856-1857. It is found on Waterbury type 2.411 movements, usually in clocks with Chauncey Jerome labels but also labels of the Waterbury Clock Co.