As new fields are developed in the realms of science, monographs and books given over to the new developments appear with appalling regularity. Some are elementary, some are comprehensive, and some are between the two. In the new field of slit lamp microscopy of the living eye, or, as Jackson has so aptly termed it, biomicroscopy, four textbooks have appeared. That by Koeppe is monumental but requires a working knowledge of higher mathematics; the Atlas by Vogt is an art gallery that should be studied by every user of the slit lamp; Koby's handbook is elementary but extremely practical; the present book by Butler borrows from all three without adding anything substantial. As a book it is a credit to the Oxford University Press, but as a manual of slit lamp microscopy it leaves much to be desired. The principles and mathematics of the instrument are touched on but briefly.