Color theory primary colors work at all is that the imperfect pigments being used have sloped absorption curves, and thus change color with concentration. A pigment that is pure red at high concentrations can behave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible. Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be used to mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is even possible to mix very low concentrations of the blue mentioned and
Moving walkway the book, the fast lane stops while the second lane keeps running at ). In the Wells and Asimov works there are more steps in the speed scale and the speeds are less extreme. In Arthur C. Clarke's novel, "Against the Fall of Night" (later rewritten as "The City and the Stars") the Megacity of Diaspar is interwoven with "moving ways" which, unlike Heinlein's conveyor belts, are solid floors that can mysteriously move as a fluid. In the novel, Clarke writes, In his non-fiction book "Profiles of the Future", Arthur C. Clarke mentions moving sidewalks but made of some sort