Writing in the Chronicle of Higher Education, Stanford history prof Paula Findlen discusses the renaissance of 19th century scholarship occasioned by the mass-digitization of 19th century literature. This was only possible, of course, because the copyright on these works had expired. Findlen, who doesn't study the 19th century per se, nevertheless found the wide and deep catalog of available 19th century materials meant that an overall awareness of the literature and culture of the era has permeated historians and other scholars.
By the standards of the 21st century — or even the mid-20th — the 19th century record is sparse to the point of nonexistence. But the lack of restrictions on duplication and — especially — indexing means that this world is particularly vivid for people who are paying attention.
As I've noted, I love 19th century Punch almanacs, love their physicality, but the mass-digitization and cross-referencing of them makes the physical ones a thousand times better.
This rediscovery of the 19th century as an open-source reading experience is accompanied by a subtle appreciation of the era's intellectual merits. Consider the quantity of material—obscure novels, local histories, antique catalogs, minor journals, a sea of biographies, and those vast and terrifyingly erudite bibliographies that were a specialty of that age of scholarship…
…We now have access to one of the most valuable tools of archival and bibliographic research: the 19th-century catalog. It often contains precious annotations of the process by which living artifacts become a historical record—the quirky details that tend to be lost in modern information systems, which strip away the idiosyncrasies of personalized description in favor standardized data. In a way, the experience of using Google to access the 19th century has enriched our ability to work in the physical archives and libraries that many of us still consider to be the epicenter of scholarship. I am constantly moving between my Victorian online experience and the far richer evidence available at some brick-and-mortar libraries.