He quickly became an expert on early typography and began describing every known European type fount used before 1520.

[2] Proctor developed a Greek typeface based on type found in the Complutensian Polyglot Bible.

In December 1903 a judge granted an order presuming Proctor's death on 6 September of that year.

[7] After Proctor's death a memorial fund was established and used to collect and publish (in 1905) his Bibliographical Essays.

The fund also provided for the compilation and publication of the three remaining parts of Proctor's index of early printed books covering the years 1501 to 1520.