He had them copied out into new manuscripts, and used his best guesswork to fill in the gaps where the originals were unreadable.
hiː hˌædðɛm kˈɑːpɪd ˈaʊt ˌɪntʊ nˈuː mˈænjuːskɹˌɪpts, ænd jˈuːzd hɪz bˈɛst ɡˈɛswɜːk tə fˈɪl ɪnðə ɡˈæps wˌɛɹ ðɪ ɚɹˈɪdʒɪnəlz wɜːɹ ʌnɹˈiːdəbəl.