Willy Ley’s 1969 Another Look at Atlantis and Fifteen Other Essays is a collection of non-fiction pieces. From 1952 to his death in 1969, Ley had a regular science column in Galaxy Magazine, For Your Information. As far as I can tell, none of these essays were drawn from that source.
This was my first exposure to Ley. If I am reading the bibliographic information correctly, it was the final Ley book published while Ley was alive.