This first image is a snap-back Rebberg Rolex watch from 1914. Essentially it is a pocket watch on a leather strap.
If you look closely at the image above, you notice the watch has a hinge on the left side of the case. If you flip the watch around onto its face (as seen below) you notice if you open the rear door it exposes the movement. (Note: the snap-back door on the photo below is not in sharp focus, but it is on the left edge of the photo sitting upright, perpendicular to the case). The challenge is, there is no seal or gasket to stop dust, perspiration, water or humidity from entering the case.