Alison,
A book on a similar theme regarding those one-use holes and the proper way
to hide your doo doo is titled "How to Shit in the Woods: An Environmentally
Sound Approach to A Lost Art." by Kathleen Meyer, and published here in the
U. S. You can find in on Amazon.com. Though it is not exactly on privies as
standing vernacular architecture, or totally tongue-in-cheek, it covers the
act for which privies are built and might be an interesting sidebar to your
thesis.
--
Michael Strutt
Staff Archeologist
Center For Historic Preservation
Middle Tennessee State University
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"Work is the curse of the drinking classes" - Oscar Wilde