Hip and valley design details, formulae and graphics, roofs, hoppers and pipe lines This book, "Hip and valley design details, formulae and graphics, roofs, hoppers and pipe lines", by H.L. McKibben, is a replication of a book originally published before 1912. It has been restored by human beings, page by page, so that you may enjoy it in a form as close to the original as possible. This book was created using print-on-demand technology. Thank you for supporting classic literature.