The book has no 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 the publisher's website (GeneralBooksClub.com). You can also preview excerpts of 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: 2; Original Publisher: Research Division, American Optical Co.; Publication date: 1921; Subjects: Physiological optics; Medical / Neuroscience; Medical / Ophthalmology; Medical / Optometry; Science / Optics;