ABC Marginalia

[ReneZ]

The Jesuits in Rome made many pencil annotations on Kircher's correspondence, so my first tendency is to suspect that they may have been responsible for this too.

This is of course speculative.

There is equally a record of Voynich adding pencilled annotations on his manuscripts (not just the inside covers or endpapers), so Helmut's suggestion is also possible. It doesn't look like his hand, though, even though I don't have many samples of that.