Case (1858-1916) was a blackface comedian I encountered while researching the history of SJI; he makes a brief appearance in the book.
Charley Case would stand alone on a stage and recount elaborate tales while twirling a bit of string between his fingers. His comedy was subtle; his audience often "got" the joke after Case had already launched into his next narrative, interrupting it with gales of laughter. Extremely popular in his time but forgotten now, he was, I think, the original American standup comic.
From a writer's perspective, the problem with Case is that very little is known about him. The most complete history is documented in twenty pages of the book Lost Sounds: Blacks and the Birth of the Recording Industry 1890-1919. This is not much to base an entire book upon.
So ... can anybody out there help? Case died tragically, unaware of his importance in the evolution of popular entertainment. Without Charley Case in the background, Richard Pryor (or Milton Berle) would have been an entirely different comedian. He was that significant.