An alternative comment:

I've found people's handwriting deteriorate as time has gone by... cursive is rarer to come by (leaving the 'legibility' argument aside), typing has certainly contributed to this, but some people still write on boards to explore ideas and boy are those diagrams and writings unreadable.

If the author posted some samples of the grandfather's notes (withholding personal information), that would have added a very personal touch to the article indeed, and also ensured his ancestor's work gets recorded by archive.com.

edit: grammar.