Lucio Russo (Università di Roma “Tor Vergata”)
The systematic error on longitudes in Ptolemy’s Geographia and his reduced estimate for the dimension of the Earth are examined. The thesis is exposed that the shrinking of the dimension of the Earth is a consequence of the scale error on the longitudes, which, in turn, was originated by a misidentification of the Islands of the Blessed. The location of the Islands of the Blessed according to the source of Ptolemy should be identified in the Caribbean. Two other independent quantitative arguments lead to the same conclusion, which sheds new light on possible contact among civilizations.