Presumption for old documents: genuineness of handwriting and due execution follows when custody is proper. Where a document purports or is proved to be thirty years old and is produced from custody the Court considers proper, the Court may presume that signatures and parts purported to be in a person's handwriting are genuine and that executed or attested documents were duly executed and attested; the Explanation to section 80 applies, and statutory illustrations identify long possession, mortgagee custody, and deposited safekeeping as examples of proper custody.