One of the best references for pipe organs is the well-written
"The Art of Organ Building" by Audsley (if my memory serves me).
It is in two volumes, and many libraries have it.  It explains pipe
scales, intonation, materials and building techniques.

It was written about 1912 or so, but much of it is still valid today.
If you overlook the author's opinion as to what proper organ tone is,
you will find a lot of interesting (somewhat historical) information.
Pipe scales don't change with time.  It was originally published in
England, but I have seen newer copies.

Bill Chapman

 [ The Art of Organ-Building, by George Ashdown Audsley, Publ. by
 [ Dodd, Mead, and Company, New York, 1905.  The Dover edition, first
 [ published in 1965, is an unabridged republication of the book with
 [ corrected and improved illustrations.  Dover proudly trumpets:
 [
 [ "Not a word of the first edition has been omitted, giving you all
 [  of Audsley's famous 1,300-page text -- unquestionably the greatest
 [  repository of material on organ building and history ever compiled
 [  in the English language."
 [
 [ I have Volume 1, ISBN 0-486-21314-5, price $17.95, available from
 [ Dover Publications, Inc. 31 East 2nd Street, Mineola, N.Y. 11501.
 [ This volume has been most useful.  Volume 2 is specifications of
 [ organs.
 [
 [ -- Robbie