taking it directly to the source
from Calvinism: An Interpretation of Its Basic Ideas, H. Henry Meeter, 1939
(transcript below)
- pencil (beautiful cursive, writes v lightly)
- pencil (cannot underline with a straight line)
- pencil (underlines so hard the paper is borderline scarred, probably using harder lead than #2 given color and denting)
- dull pencil (marginal x-es not near other pencil underlining)
- navy fountain pen
- medium blue ballpoint
- navy ballpoint (ruler user)
- blue ballpoint (faint1)
- black ballpoint
based on analysis of other marks:
- faint blue ballpoint user is likely unique and/or is not one of the main three pencil users (uses marginal checkmarks, which occasionally appear in pencil)
- black ballpoint is different from medium blue ballpoint, as marginal stars have a completely different stroke pattern
- ruler user seems to have used the same writing utensil throughout
- wobbly pencil underliner uses marginal asterisks, so is likely different from black ballpoint (sometimes wobbly, always stars)

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less obtrusive than writing heavily so kudos there I guess, but still why are you doing this

