The English bibliographer Robert Proctor transformed the study of incunabula by placing it on a scientific footing. His major achievement was the classification of all of the types used by fifteenth-century printers into a system that showed the spread of printing by countries, towns, and individual presses. In no more than four years of intensive work he digested the materials and published An Index to the Early Printed Books in the British Museum from the Invention of Printing to the Year MD, with Notes of Those in the Bodleian Library (1898-1903), which was recognized at once as a milestone in incunabular studies. In the words of his successor, Victor Scholderer, "The immediate result of the publication of the Index was somewhat comparable to that of the launching of H.M.S. 'Dreadnought' in 1906. It gave instant pause to the experts, who after a time made its conclusions their...