Via the always brilliant
Maps Mania, we are treated to a thorough-going survey of the interventions and fillers that cartographers of the past used to cover gaps in their geographical knowledge (see also
here,
here and
here) informed of course by their contemporary understanding of the world and what possibilities it supported. Another technique applied to atlas obscura were the bordering clouds of
Edward Quin’s 1830 historical gazetteer with receding overcast skies paralleling humanity’s growing world-view.
