The publishers and compilers who produced how-to books for Chinese common readers undertook various forms of epistemic translation in creating usable, actionable, knowledge. They juxtaposed and interwove seemingly incommensurable elements—foreign methods, past techniques, and lived experience—into innovative assemblages that guided readers in managing disease, preserving foodstuffs, and applying new technologies. This lecture first conceptualizes vernacular knowledge which I define as the explanatory framework for practical know-how. It then sketches the broad corpus of how-to texts that disseminated this knowledge in early twentieth century China, and introduces one exemplary work, the repeatedly reprinted Ocean of Secret Techniques.