The pervasiveness of American slating references here, particularly in this century, is unquestionable. American architectural books and construction guides, which were well known in Canada, often contained advice to slaters or to roof replace contractors. The Canadian Architect and Builder in answer to inquiries concerning slate drew on American pocketbook authorities such as Kidder and Hodgson. That Hodgson was, in fact, a Canadian could suggest a greater exchange of technical experience between Canada and the United States than his co-authored publications out of Chicago might imply. American dominance of the architectural press in North America was, nevertheless, paramount and was reflected in journals like The Canadian Engineer that reprinted articles on slating from American periodicals such as Stone andВ reported American research on slate.В The United States quarries and their agents also produced pamphlets for their clients, Canadians included, explaining the kinds of slate and how slates were put on the roof. The National Slate Association, organized in 1922 by American slate producers, architects and contractors published a 1926 handbook, Slate Roofs, detailing information on types of slate, roof construction and slate application techniques. Definitions for standard, textural and graduated slate roofs worked out by the Association were the basis of roofing slate standards adopted by the American Society for Testing Materials (ASTM) and influenced slate specifications adopted by the as Canadian Bureau of Standards. as The 20th-century standards for roofing slate were building material classifications that did not encompass application practice.