The book may have numerous typos or missing text. It is not illustrated or indexed. However, purchasers can download a free scanned copy of the original rare book from the publisher's website. You can also preview the book there.Purchasers are also entitled to a trial membership in the publisher's book club where they can select from more than a million books for free.Original Publisher: National Academies Publication date: 1948-01-01Original Identifier: NAP:16573 Description: Vols. for include reports for the National Research Council; 1965/66- include reports for the National Academy of Engineering; 1971/72- include reports for the Institute of Medicine. Subjects: Science; Education / Teaching Methods