The value structure of Oswald Achenbach is mid-key: quiet, controlled, and cohesive. Oswald Achenbach tilts toward cool - blues and silver-greys carry the structural weight. All colours lean toward grey, building depth through value rather than colour punch. The most saturated colour, #423725, is reserved to 10.5% of the surface, where it acts as a focal punctuation. The full value range is 80 units: broad enough to build convincing three-dimensional form. High luminosity and cool temperature suggest the plein-air condition: unfiltered daylight and open sky. Palette 4 sits within the larger chromatic argument that Oswald Achenbach's complete body of work advances.