Razor baseplate, clarified
A three-piece safety razor comprises a handle, a baseplate, and a cap. The orientation of two is obvious: the cap has a threaded stud and the handle as a tapped receptacle for the stud: the handle and cap are screwed together, with the baseplate (holding a double-edged razor blade) squeezed between.
So the baseplate is the only piece with a possibly ambiguous orientation, and a few beginners find that they’ve attempted their first shave with the baseplate upside down (which doesn’t work). In the next edition, I’m going to include this photo and explanation:
The two baseplates are both from Edwin Jagger/Mühle razors of recent manufacture: this is the new head. The baseplate at the bottom is upside down: the blade goes on the other side; the baseplate at the top is rightside up: you just put the blade atop the side with the scalloped edges and the cap goes on top of that.