From J. Robert Wagner
A possible explanation for that ancient archaeological puzzle, the Severan Marble Plan, could be that it was for the purposes of collecting taxes (2 October, p 36). One could easily keep track of who had paid their taxes by making notes on the surface of the map using charcoal, wax or something else easy to erase for next year’s record. Although the map was displayed high off the ground, it could be reached by ladders on rollers, like those in large libraries.
Plymouth Meeting, Pennsylvania, US
