 A detail in one illustration suggests that it is set in or around the year 1803, and at least one character is depicted in clothing and wig reminiscent of that era; but Ratbridge is already so industrialised that certain industries have collapsed in the depletion of natural resources.Large electric generators, a product of the mid-19th century, are in operation, as are bicycles (developed in the 1880s).It presupposes the ready availability of cardboard boxes, an invention of the 1850s, and also of cardboard recycling programmes.