Proportional circle maps are similar to dot distribution maps, with an added element. The sizes of the dots vary with size in proportion to the data displayed in the given boundaries. This map looks at population sizes a French provence. The size of the dots give a quick reference to the population sizes, though exact accuracy is not expressed.
Found - www.stat.columbia.edu
This blog is a map catalog in which I am displaying fifty different types of maps and a tid-bit of information that looks into the purpose of the map!