The book I mentioned was The Shuttle-Craft Book of American Hand-Weaving by Mary Meigs Atwater. The copy I looked at was from the fifth printing in 1961, but the book was first published in 1928.
"If a smooth fabric in plain tabby is to be woven the warp-yarn and weft-yarn used should be twisted in opposite directions, otherwise when finished the fabric will have a crepey effect. The right-hand or "Z" twist is usually the warp-twist and the left-hand or "S" twist the weft-twist, but this does not seem to be an invariable rule." - p. 58.
Eileen sent me another note, too:
I am starting the new Dye-Lishus® cotton fabric line. I am selling it wholesale, so the shops who will be carrying will be on the map on my new website.
- Ashford Traditional Wheel (often called a "traddy")