You're welcome. Here's a few inexpensive books on American coin silver that contain that mark.
Stephen Ensko's "American Silversmiths and Their Marks", Kovels, and an old book "Silver & Pewter marks" by C. Jordan Thorn.
The scan of marks below came from C. Jordan Thorn's book.
Here's a tea service that John and James Cox made, it's in the Brooklyn museum:
Pat.
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