There is no rule limiting the number of illustrations that may be used in a publication of the Geological Survey, but in selecting illustrations for a report an author may easily fall into the error of over-illustration. The number of diagrammatic drawings or of drawings that express the author's deductions is rarely in excess of the needs of a paper, but the number of photographs submitted is often excessive. The number of pages in a manuscript may be a factor in determining the proper number of illustrations, but as the need of illustrations varies greatly from paper to paper this factor alone is not decisive. The tendency to overillustrate led the Director to issue the following order[1] governing the approval of illustrations: [Footnote 1: From Survey Order 63, Oct. 20, 1915.] The primary responsibility for the selection of illustrative material shall rest upon the author and the chief of the branch transmitting the report: No one knows the subject matter of the report better than its author, though a sympathetic critic is usually needed to correct the personal equation that may express itself In an excessive number of illustrations or the use of photographs into which no one but the field man himself can read what he wishes to illustrate. The approval by the chief of branch of the illustrations selected by the author will be taken as vouching for those illustrations as essential and adequate, and the scientific value of the illustrations will not be subject to review in the section of illustrations. The chief of the section of illustrations shall decide the technical questions relating to the preparation of these illustrations for reproduction and may recommend the rejection of any that do not promise effective or economical reproduction. In the consideration of such questions, especially any relating to maps, the cooperation of the editor of geologic maps and chief engraver will be expected. The judgment of an author as to the illustrative value of a photograph is likely to be biased by his knowledge of the features that are actually included in the view represented, not all of which may be shown clearly in the photograph; his knowledge of all the features enables him to see more in his picture than his readers will be able to recognize without detailed description. Photographs in which special or significant features are obscured by foliage or lost in hazy distance do not make acceptable illustrations, and the use of a picture that requires much description to make it illustrate reverses, in a measure, the relations of text and illustrations.