It hardly seems possible to add anything to make the book more complete as a practical work. The reader is assumed to have already a knowledge of elementary photographic processes, and the author has not attempted to deal with the historical or theoretical features of the half-tone process. The book aims at being a guide to the current practice of working the half-tone process, and obsolete or little-used processes have been ignored, except in so far as it might be necessary to refer to them as explanatory of the advantages of the newer methods. The Chapter on three-colour half-tone has been brought up to date with substantial additions, as demanded by the considerable progress which has been made in this department since the issue of the last volume. It must be remembered, however, that to treat this subject properly would fill a volume in itself, and the author has therefore been unable to do more than indicate how black and white half-tone merges into three-colour work. A new Chapter has been added dealing with duo types and two — colour half-tones.