I found the mag from 2002.... The article quotes(paraphrases) the original Ye Sylvan Archery article from 1936. It says heat tempering was used to rapidly season, temper a new stave to improve cast or reduce/eliminate string follow in a used bow with bad string follow.
The author of the PA article speculates that this was a forgotten secret not known to many modern bowyers. He says that space constraints made it impossible to cover the particulars of the process in his own article.
It would be neat if someone actually had the original article from 193 to see how similar it is to what we do now.