#15748

What you have taken to be lathe marks (from machining after casting) are actually sweep marks from when the mold for this bell was made. None of the American bellfoundries were tuning their bells at such an early date, and most of them never did.

For cast bronze bells, the year (when present) is always the year of casting. That’s partly because the mold is single-use; it has to be broken to get the bell out of it after it’s cooled.

For cast steel bells, the year (when present) is typically on the cast iron yoke, not on the bell itself. In that case, it’s most likely a design or patent date, because molds for cast iron are re-usable.