How to make a crochet hat the right size - I have been using this same method lately. Its hard to follow a pattern exactly when you are constantly using different yarn. For an adult female, the hat should fit if you crochet a circle until it measures 5 1/4 FLAT (stop your increases at that point). For a mans hat, stop you increases when your circle measures about 6 1/4 FLAT.
A lace guide for makers and collectors with a bibliography and five-language nomenclature, profusely illus. with halftone plates and key designs by Gertrude Whiting ... Published 1920 http://openlibrary.org/works/OL6704819W/A_lace_guide_for_makers_and_collectors