This is an OCR edition without illustrations or index. It may have numerous typos or missing text. However, purchasers can download a free scanned copy of the original rare book from GeneralBooksClub.com. You can also preview excerpts from the book there. Purchasers are also entitled to a free trial membership in the General Books Club where they can select from more than a million books without charge. Volume: 24-25; Original Published by: National Academies in 1967 in 448 pages; Original Identifier: NAP:15508; Subjects: Technology & Engineering / Electrical; Technology / Engineering / Electrical;