Did The New Yorker ever publish its stylebook? Where might a copy be
found? It need not necessarily be an up-to-date version. 

If The New Yorker did not publish such a thing, does The New York
Times stylebook (or the published stylebook for another major daily) 
contain style guidelines for its Sunday magazine?

Do you have the AP Stylebook?

http://www.amazon.com/exec/obidos/tg/detail/-/0738207403

The New York Times Manual of Style and Usage?

http://www.amazon.com/exec/obidos/tg/detail/-/0812963881

Thanks, Pinkfreud: I have access to both. I'm particularly interested
in the idiosyncracies of The New Yorker or, failing that, The New York
Times magazine, which are the most formal that I've seen. I think the
Times's manual covers only the newspaper, but can find that out for
myself if no researcher happens to know. I've been told that The New
Yorker published its stylebook once upon a time, but I've seen no
evidence of it.

McCook-ga

I cruised around for about an hour seeking evidence of a stylebook for
"The New Yorker," but I came up empty-handed.

Perhaps my lack of a stylebook explains why I have not yet been
published in "The New Yorker." ;-)

Pinkfreud-ga: Thanks for the thorough search. As I suspected, there
probably is no such thing in re. The New Yorker. I'll keep digging.

McCook-ga

mccook --

I haven't been able to nail this one down either, although I strongly
suspect that an answer may be found in one of the many books that have
been written about The New Yorker over the years.  Here is a link to a
partial list of those books:
All About The New Yorker
http://hallbook.com/nonfiction/8.shtml

The one bit of information I was able to find was in a forum hosted by
wordsmith.org. A correspondent had the following to say in a
reminiscence from the mid-50s:

"One day . . .  I wrote a one-page letter to the Editor of the
magazine, asking where I could obtain a copy of its Style Manual. . .
. The response came quickly and it was signed by E.B. White, who had
appointed himself to answer my letter. First, he said that the New
Yorker had no Style Manual or Guide or anything else in writing to
tell people how to write . . .  ."
A Word A Day: Mail Issue 41
http://www.wordsmith.org/awad/awadmail41.html

markj-ga