The citation for Harry Lindgren's 13-piece dissection of three hexagrams to one should be (1964b). The citation for his 12-piece dissection should be (1964a), which incidentally should be entitled "Dissections for Schools". The figures for that article do not appear on pages 52-54, but rather in the Supplement.
(This is corrected in the paperback edition.)
Also, the citation for Lindgren's 18-piece dissection of three enneagons to one should be (1964a).
In Ernest Freese's manuscript, Geometric Transformations (completed before his death in 1957), which I got access to in February 2003, there is a diagram (on Plate 86) of the same 12-piece dissection of three hexagrams to one that Harry Lindgren published in 1964.
In Figure 17.15, I used a certain trick to produce the side of the large octagon. You will see six identical pieces in my dissection, and construction of these pieces relies on the trick. This trick was described much earlier in Abu'l-Wafa's manuscript "On the Geometric Constructions Necessary for the Artisan". The trick, along with an accompanying figure, is discussed in the article "Mathematics and Arts: Connections between Theory and Practice in the Medieval Islamic World", by Alpay Özdural, Historia Mathematica, vol. 27 (2000), pp. 171-201. Follow this link to view the abstract.
I made a mistake in the biography of C. Dudley Langford, claiming that his Ph.D. was in mathematics. Actually, all of his degrees were in chemistry, as he states in a letter to Harry Lindgren dated August 11, 1962.
Our favorite private mathdick has uncovered a valuable clue that may lead to important discoveries: The official name of an {11} is a "hendecagon", according to John Conway, at Princeton. Now don't go out and get yourself busted.
Copyright 1997-2003, Greg N. Frederickson.
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Last updated August 10, 2003.