My long and happy relationship with Scientific American, back in the days when Gerard Piel was publisher and Dennis Flanagan was
the editor, began in 1952 when I sold the magazine an article on the his-
tory of logic machines. These were curious devices, invented in pre-
computer centuries, for solving problems in formal logic. The article
included a heavy paper insert from which one could cut a set of win-
dow cards I had devised for solving syllogisms. I later expanded the ar-
ticle to Logic Machines and Diagrams, a book published in 1959.
My second sale to Scientific American was an article on hexa-
flexagons, reprinted here as Chapter 29. As I explain in that chapter's
addendum, it prompted Piel to suggest a regular department devoted to
recreational mathematics. Titled "Mathematical Games" (that M. G. are
also my initials was a coincidence), the column ran for a quarter of a
century. As these years went by I learned more and more math. There
is no better way to teach oneself a topic than to write about it.