ABC Marginalia

[Sam G]

I'm not an expert on this, but to me it actually looks like 1r has been written with a different utensil than the others. I see more clearly the quill strokes in it, while the others look almost modern.

I've seen these referred to as being in "pencil", so you may be right, though it's not obvious to me what kind of writing implement was used.  Also, I should mention that I upped the contrast on these to make the shapes of the letters more visible, so it's probably better to look at the original scans if you want to try to determine that kind of thing.