“Jean-Jacques Lequeu (Rouen, September 14, 1757 – 28 March 1826) was a French draughtsman and architect. […] He spent time preparing the Architecture Civile, a book intended for publication, but which was never published. Most of his drawings can be found at the Bibliothèque nationale de France. Some of them are pornographic and are kept in the Enfer of the library.” (wikipedia)

More drawings at the Bibliothèque Nationale de France.