The second paragraph in the snippet reads "The airfoil of the wing comes from Fritz Bosch, co-winner of the 1963 Internats. It is a 20%, symmetrical section with a sharper leading edge than is now popular, providing better spinning tendencies."

The drawing seems to be a bit vague (obviously, the section is not drawn symmetrical), but it closely resembles a modified NACA 0020 (NACA 0020-33), the thickest point being at 37% chord (instead of 30%). See second airfoil picture.

Difference to the NACA 2419 mod (what modification?) is only symmetry and aft position of thickness. The latter makes for the sharper nose, not a smaller radius. Maybe Ed's 2419 mod even had a slightly more aft thickness, giving nearly the same upper curvature as the Bosch airfoil. At least that would explain why the wing saddle matches both wings. See third airfoil picture, incidence exactly -1.17 degrees.

Seems Ed simply took the upper part of the 2419 airfoil, mirrored it as lower part to get 20% thickness (or still 19%, see his drawing), and drew a correct leading edge shape (maybe getting a small kink at about 7% chord).

BTW, the airfoil in the last picture is a 2419 mod (2419-33), drawn with Martin Hepperle's Javafoil program ([link=http://www.mh-aerotools.de/airfoils/javafoil.htm]http://www.mh-aerotools.de/airfoils/javafoil.htm[/link]). There is no modification at all (done by me). Only selecting the "mod" series instead of the standard 4-digit NACA series gives a slightly more aft thickness and sharper leading edge.

The airfoil mystery unraveled?