Parallel lines from opposite ends of the world, after Ptolemy
A note on parallels citing Ptolemy's Cosmography
Two line segments at the head of the folio, extended by dotted lines, illustrate a note on parallels: a line begun at one end of the world can remain parallel and equidistant from another begun at the opposite side. Leonardo grounds the claim in Ptolemy's Cosmography, which shows cities at opposite ends of the earth lying on the same parallel.
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Parallel, equidistant lines drawn from opposite ends of the world
Two segments at the head of the folio, extended by dotted lines, argue that a line begun at one end of the world can remain parallel and equidistant to one begun at the opposite side.
Ptolemy's Cosmography: cities on the same parallel
Leonardo cites Ptolemy's Cosmography, which shows cities situated at opposite ends of the earth as lying on one and the same parallel of latitude.