If you look at the rest of that 1947 timetable I think you'll find PA didn't fly to Ascension, despite the map. Don't think they ever did; maybe Panair do Brasil never did either?

Didn't find a Dakar-Idlewild nonstop DC-7C in the few 1957-59 Guides I checked; I'll check 1960 but doubt it's there either.

Edit: PA 1960 timetables do show a weekly DC-7C nonstop each way DKR-IDL.

The 1950 map shows the Johannesburg route via Ascension as 'authorized but not operated'....so maybe they never did fly it commercially
http://www.timetableimages.com/ttima...50/pa50-07.jpg