Early Recordings of Black Preaching

[John Harvey]

I am a British academic with an interest in the musicality of black preaching and bible reading. I would like to hear examples particularly from the first part of the twentieth century. To this end,  I'm searching for 78 rpm and wax cylinder recordings of these practices. If anyone knows of sources or archives (either physical or digital) of these recordings, I'd be most grateful to know.

Many thanks,  John