Bengt Frokenberg (1776-1845) - Hercules Pen and ink on paper

Artist: Bengt Frokenberg (1776-1845), or another earlier artist relating to the pen inscription of a 1761 date.
Title: Hercules
Medium: Pen and ink on paper
Size: 320 x 200 mm
Signed: no
Notes: Inscription in pen at bottom right, 1761. 0.23my. [Is 1761 a date? Don’t know what the other stuff means]. If 1761 is a signed date then it is not Bengt Frokenberg (1776-1845).
Paper sheet has a Pro Patria watermark. Pro Patria paper dates from 1716.
A version, possibly this one, was done by some artist and is included in the 1824 edition of John Tinney's book "A Compendious Treatise of Anatomy, .... ", with Plate X being this ‘Hercules’ image, and only included from 1824.
This image initially came from an album of original watercolours and drawings attributed to Bengt Frokenberg. Were they all done by him, or are some by other artists?