What a couple of amazing machines!
That first one has a truly marvelous motion .... what would you call that, a broken beam engine or possibly split beam, hinged beam, counter beam ... or???
Whatever you call it, by any other name, it is amazing!
The second one obviously uses a pair of air-cooled cylinders as the basis, and a sort of modified form of a Ross yoke, I think, to link the two engines together. Lycoming aircraft cylinders, motorcycle cylinders, something else entirely type of cylinders .... who knows??? I sure like the slow speeds that it is capable of maintaining!!!