(Jon of the Clue Crew points to an astronomical diagram on the monitor.)  In the 200s B.C. Eratosthenes calculated Earth's girth using the difference in the angle of the Sun's rays between Aswan & this Egyptian city
When the Naval Research (laboratory astronomers 
measured the radio... [DOC] [TLE] Full text of "The Atlantic; a history of an ocean" - Internet Archive [PAR] Today the word "Atlantic" will bring to mind a different image for each different 
reader.