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+*** START OF THE PROJECT GUTENBERG EBOOK 43232 ***
+
+Transcriber's Note
+
+Italicized text is displayed as _Text_ and bold text as =Text=. Whole
+and fractional parts of numbers are displayed as 4-5/8. Some UTF-8
+characters were converted to plain ASCII. To view them, see the HTML
+or UTF-8 version.
+
+
+
+
+DEPARTMENT OF THE INTERIOR.
+
+John Barton Payne, Secretary
+
+
+
+United States Geological Survey
+
+George Otis Smith, Director
+
+
+
+THE
+
+PREPARATION OF ILLUSTRATIONS
+
+FOR REPORTS OF THE
+
+United STATES GEOLOGICAL SURVEY
+
+WITH BRIEF DESCRIPTIONS OF PROCESSES
+
+OF REPRODUCTION
+
+
+
+BY
+
+
+
+JOHN L. RIDGWAY
+
+
+
+
+WASHINGTON
+
+GOVERNMENT PRINTING OFFICE
+
+1920
+
+
++==================================+
+| |
+| THE PREPARATION OF ILLUSTRATIONS |
+| |
+| FOR REPORTS OF THE |
+| |
+| UNITED STATES GEOLOGICAL SURVEY |
+| |
+| |
+| BY |
+| |
+| |
+| JOHN L. RIDGWAY |
+| |
++==================================+
+
+
+CONTENTS.
+
+
+Part I. Preparation by Authors.
+
+ Page.
+
+ Introduction 7
+ Purpose and value of illustrations 8
+ Selection and approval of illustrations 8
+ Submittal of illustrations 10
+ Kinds of illustrations 10
+ Sizes of illustrations 11
+ Subdivisions of plates and figures 12
+ Preparation of copy by authors 12
+ Character of original material 12
+ Preliminary preparation of maps 13
+ Material available for base maps 14
+ Basic features of maps 17
+ Standard scales 18
+ Orientation of maps 18
+ Projection 18
+ Explanation 19
+ Titles of maps and other illustrations 19
+ Symbols used on maps 20
+ General features 20
+ Letter symbols 20
+ Oil and gas symbols 21
+ Symbols for use on maps showing features of ground water 21
+ Black-line conventions 23
+ Materials used in preparing maps 23
+ Paper 23
+ Bristol board 24
+ Tracing linen 24
+ Inks 25
+ Drawing pens 25
+ Pencils 25
+ Rubber erasers and cleaners 25
+ Colored pencils and crayons 26
+ Water colors 26
+ Japanese transparent water colors 26
+ Coloring geologic maps 27
+ Diagrams 28
+ Essential features 28
+ Plans of mine workings 29
+ Sections 29
+ Lithologic symbols 32
+ Use of photographs as illustrations 32
+ Essential features 32
+ Copyrighted photographs 33
+
+ Sources of photographs 34
+ Lending original photographs and drawings 34
+ Unpublished photographs 34
+ Specimens 34
+ General requirements 34
+ Borrowed and fragile specimens 35
+ Transmittal of paleontologic specimens 35
+ Making up plates 36
+ Reuse of illustrations 37
+ Approval of finished illustrations 38
+ Revision of illustrations 38
+ Submittal of proofs 38
+ Proof-reading illustrations 39
+ General considerations 39
+
+
+ Part II. Preparation by Draftsmen.
+
+ General directions 41
+ Instruments 42
+ Classification of material 42
+ Preparation of maps 43
+ Projection 43
+ Details of base maps 45
+ Transferring or copying 46
+ Tracing 46
+ Celluloid transferring 47
+ Sketching by reticulation 47
+ The "shadowless drafting table" 47
+ Topographic features 48
+ Relief 48
+ Hydrography 51
+ Cultural features 52
+ Lettering 53
+ General directions 53
+ Lettering by type 54
+ Abbreviations 55
+ Names of railroads 57
+ Make-up of maps 57
+ Forms for certain features 57
+ Border 57
+ Title 58
+ Explanation 58
+ Graphic scales for maps 59
+ Symbols 61
+ Areal patterns for black and white maps 61
+ Standard colors for geologic maps 63
+ Reduction or enlargement of maps 63
+ Diagrams 64
+ Sections 64
+ Plans and cross sections of mines 65
+
+ Drawings of specimens of rocks and fossils 66
+ Methods used 66
+ Brush and pencil drawings 66
+ Pen drawings 67
+ Retouching photographs of specimens 68
+ Landscape drawings from poor photographs 68
+ Pen drawings made over photographs 68
+ Brush drawings from poor photographs 69
+ Outdoor sketches 69
+ Drawings of crystals 70
+ Retouching photographs 70
+
+
+ Part III. Processes of Reproducing Illustrations.
+
+ Methods employed 72
+ Photoengraving 72
+ General features 72
+ Zinc etching 73
+ Copper etching in relief 75
+ Half-tone engraving 75
+ Three-color half-tone process 78
+ Wax engraving (the cerotype process) 80
+ Wood engraving 81
+ Photogelatin processes 82
+ Lithography 83
+ Original process 83
+ Photolithography 86
+ Offset printing 87
+ Chromolithography 87
+ Engraving on stone and on copper 89
+
+
+ Appendix.
+
+ Length of degrees of latitude and longitude 91
+ Metric system and equivalents 92
+ Geologic eras, periods, systems, epochs, and series 92
+ Chemical elements and symbols 93
+ Greek alphabet 93
+ Roman numerals 93
+ Mathematical signs 94
+ Names of rocks 94
+
+
+ILLUSTRATIONS.
+
+ Page.
+
+Plate I. Methods of inserting plates and figures 10
+
+ II. Symbols used on geologic maps, economic maps,
+ and mine plans 20
+
+ III. Lithologic symbols used in structure and columnar
+ sections to represent different kinds of rock 32
+
+ IV. Symbols used on base maps 52
+
+ V. Reduction sheet used in lettering illustrations 54
+
+ VI. Half-tone prints showing effects produced by the
+ use of six standard screens 56
+
+ VII. Details of the make-up of a geologic map 58
+
+ VIII. Patterns used to show distinctions between areas
+ on black and white maps 60
+
+ IX. Diagrams and curves 64
+
+Figure 1. Diagrams showing principal, guide, and auxiliary
+ meridians, standard and special parallels and
+ correction lines, and system of numbering
+ townships, ranges, and sections 16
+
+ 2. Conventional lines used in preparing plans and
+ diagrams of mine workings to distinguish
+ different levels 29
+
+ 3. Section and perspective view showing relations
+ of surface features to the different kinds of
+ rocks and the structure of the beds 30
+
+ 4. Sections of coal beds 31
+
+ 5. Diagram illustrating method of projecting a map 44
+
+ 6. Methods of expressing relief by contour lines,
+ by hachures, by shading on stipple board, and
+ by a brush drawing 49
+
+ 7. Designs for bar scales 60
+
+ 8. Method of making a bar scale for a map of
+ unknown scale 60
+
+ 9. Map bearing six areal line patterns 62
+
+ 10. Diagram showing method of marking maps for
+ reduction or enlargement (for record) 64
+
+ 11. Structure section showing method of determining
+ the succession of folds 65
+
+
+THE PREPARATION OF ILLUSTRATIONS FOR REPORTS OF THE United STATES
+GEOLOGICAL SURVEY.
+
+
+By John L. Ridgway.
+
+
+
+
+PART I. PREPARATION BY AUTHORS.
+
+
+
+
+INTRODUCTION.
+
+
+There has been an obvious need in the Geological Survey of a paper
+devoted wholly to illustrations. No complete paper on the character,
+use, and mode of preparation of illustrations has been published by
+the Survey, though brief suggestions concerning certain features of
+their use have been printed in connection with other suggestions
+pertaining to publications. The present paper includes matter which it
+is hoped will be of service to authors in their work of making up
+original drafts of illustrations and to draftsmen who are using these
+originals in preparing more finished drawings, but it is not a
+technical treatise on drafting.
+
+The effectiveness of illustrations does not depend entirely on good
+drawings nor on good reproduction; it may be due in large part to the
+inherent character of the rough material submitted. If this material
+is effective or striking the finished illustrations, if well made,
+will be equally effective and striking. Each step in the making of an
+illustration--first the preparation of the author's original or rough
+draft, next the final drawing, and last the reproduction--is closely
+related to the others, and each is dependent on the others for good
+results. If the material has been well handled at all three steps the
+resulting illustration should be above criticism; if it has been
+poorly handled at any one of the three the effectiveness of the
+illustration is either impaired or ruined.
+
+A consideration of processes of reproduction is essential in the
+preparation of all illustrations, and the influence or effect of the
+process to be selected on the methods of preparing a drawing has
+seemed to warrant the presentation of brief descriptions of the
+processes usually employed by the Geological Survey. These
+descriptions include statements as to the kind of copy that is
+suitable for each process, the result produced by each, and the
+relative cost of the processes.
+
+
+PURPOSE AND VALUE OF ILLUSTRATIONS.
+
+
+An illustration in a report of the Geological Survey is not merely a
+picture having a remote bearing on the subject matter of the report;
+it must represent or explain something discussed or mentioned in order
+to become an illustration in the true sense of the term. The
+illustrations used in the Survey's reports are not employed for
+embellishment; the more pictorial kinds may be in some measure
+decorative, but decoration is distinctly not their primary purpose.
+The illustrations used in popular literature are designed to meet a
+public demand for ornament or attractiveness. Those used in scientific
+publications should be made plain and direct, without attempt to
+ornament or beautify. In the literature of science illustrations made
+by the reproduction of photographs or of explanatory diagrams or maps
+are intended simply to furnish greater illumination, and if the
+illustrations display photographic reality most statements or
+conclusions thus illuminated seem less open to dispute. A photograph
+may thus serve the double purpose of explanation and corroboration.
+The graphic expression of data and of details in a Survey report is
+intended to aid the reader in comprehending the report, and this is
+the prime advantage of its use, but it also enables the writer to omit
+from his text numerous descriptive details. It would generally be
+difficult without illustrations to present a clear picture of the
+geology of a region in its exact relations, and especially to describe
+adequately the form and the details of the structure of many fossils.
+The tasks of both the writer and the reader of reports on geology and
+kindred subjects are thus greatly facilitated by geologic maps,
+sections, paleontologic drawings, and illustrations of other kinds.
+
+The responsibility for good and effective illustrations rests largely
+upon the author, who should select and plan his illustrations with a
+view to their utility in aiding the reader to understand his report.
+
+
+
+
+SELECTION AND APPROVAL OF ILLUSTRATIONS.
+
+
+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.
+
+A photograph is not necessarily good for reproduction simply because
+it shows some particular feature to be illustrated; the quality of the
+print it will afford when reproduced from an engraved plate should
+also be considered. Some loss of detail by reproduction must be
+expected, and therefore only the clearest and most effective prints
+obtainable should be submitted.
+
+If an author has difficulty in making his preliminary or "original"
+drawings he may request that a draftsman be detailed to aid him. The
+request should be made to the Director through the chief of branch and
+properly approved. The work will then be done in the section of
+illustrations as advance preparation, but finished drawings should not
+be thus prepared unless the conditions are unusual. The administrative
+geologist reviews all illustrations submitted and represents the
+Director in matters relating to illustrations.
+
+
+SUBMITTAL OF ILLUSTRATIONS.
+
+
+All material intended for illustrations, except paleontologic
+specimens, should be submitted with the manuscript of the paper to be
+illustrated but in a separate package marked "Illustrations to
+accompany a paper on ---- by ----." The package should contain a
+carbon copy of the list of illustrations that accompanies the
+manuscript or, if the titles to be printed on or with the
+illustrations include fuller descriptions than are given in that list,
+a carbon copy of the list giving complete titles and descriptions, the
+original of which should also accompany the manuscript. In the list
+each plate and figure should be separately numbered consecutively in
+the order in which it should appear in the report, and a figure
+opposite each title should show the number of the manuscript page on
+which the illustration is first mentioned or most fully discussed.
+Roman numerals should be used for the plates and arabic numerals for
+the figures. Each drawing or photograph should bear, in addition to
+the number and title, any suggestions concerning preparation,
+reduction, and method of reproduction which the author may consider
+especially desirable. The list should be headed "Illustrations."
+
+Specimens other than fossils that are to be illustrated must be
+submitted directly to the section of illustrations, but the author may
+first obtain photographic prints of them in order to make up his
+plates. The specimens should be carefully packed and any that are
+fragile should be so marked.
+
+
+
+
+KINDS OF ILLUSTRATIONS.
+
+
+The illustrations in reports of the Geological Survey may be
+classified into five more or less distinct groups--(1) maps, (2)
+diagrams (including graphs, sections, plans, figures of apparatus, and
+stereograms), (3) outdoor photographs, (4) photographs and drawings of
+specimens, and (5) sketches. These may be further divided into two
+large groups, which may be called permanent and ephemeral. The
+permanent group includes illustrations that do not lose value through
+lapse of time or by natural alteration, such as detailed geologic
+maps, well-prepared structure sections, views of specimens, and good
+photographs or drawings of natural phenomena; the ephemeral group
+includes maps showing progress, key maps, diagrams showing yearly
+production, and many others that should be prepared in such a way as
+to minimize cost of preparation and reproduction.
+
+[Illustration: U. S. GEOLOGICAL SURVEY PREPARATION OF ILLUSTRATIONS
+PLATE I
+
+
+METHODS OF INSERTING PLATES AND FIGURES.
+
+1, 2, 3, 5, 6, 7, plates; 4, 8, 9, 10, figures; 11, pocket.]
+
+The illustrations will be finally divided into plates and figures when
+they are fully prepared, but if an author desires to determine the
+classification in advance of transmittal he should submit his material
+to the section of illustrations, where methods, processes, and
+reductions will be decided for each. In determining which shall be
+plates and which shall be figures, size and method of reproduction are
+the only factors to be considered; there are no other real
+differences. Illustrations that require separate or special printing,
+such as those reproduced by Lithography and by the photogravure,
+photogelatin, and three-color processes, must be printed separately
+from the text as plates and inserted in the report at the proper
+places; those that are reproduced by relief processes, such as zinc
+and copper etching and wax engraving, if not too large, can be printed
+with the text as figures. If an illustration to be reproduced by a
+relief process is marked for reduction to a size not exceeding that of
+the page of the text, it can be called a figure and be printed with
+the text. Half tones, though etched in relief, are rarely made text
+figures in Survey reports, because to give satisfactory impressions
+they must be printed on the best quality of coated paper, which is not
+used for the text. By using the coarser screens shown in Plate VI (p.
+56), however, a half-tone cut may be made that can be used in the text
+if it is smaller than the page.
+
+
+
+
+SIZES OF ILLUSTRATIONS.
+
+
+The regular book publications of the Geological Survey are issued in
+three sizes--(1) octavo (annual reports of the Director, statistical
+reports on mineral resources, bulletins, and water-supply papers); (2)
+quarto (professional papers and monographs); (3) folio (geologic
+folios). The following table gives the measure of the text of each
+size and the measure of the trimmed page, in inches:
+
+ Size of text. Size of page.
+
+Octavo 4-3/8 by 7-15/16 5-7/8 by 9-1/8
+Quarto 6-1/16 by 9-1/8 9-1/4 by 11-5/8
+Folio 13-13/16 by 17-7/8 18-1/2 by 21-3/4
+
+Most professional papers are printed in two columns of type, each 3
+inches wide, and folios are printed in three columns, each 4-3/8
+inches wide. A text figure in one of these publications can be made to
+fit one or more columns, and it may run the full length of the text
+page.
+
+The limits of the dimensions of plates and figures, in inches, are
+given in the following table. If for any reason a plate can not be
+reduced to the dimensions of a page it can be folded once or more; and
+if it is large and unwieldy it may be placed in a pocket on the inside
+of the back cover. (See Pl. I.)
+
+ Single-page Plate with
+ plate. one side fold. Text figure.
+
+ Octavo 4-3/8 by 7-1/2 7-1/2 by 8-1/2 4-3/8 by 7-1/2
+ Quarto 6 by 9 9-1/2 by 14-3/4 3 or 6 by 8-1/2
+ Folio 15 by 17-1/2 ............ 4-3/8 or 13-13/16 by 17-7/8
+
+For an octavo report a single-page plate with side title should be 4
+inches or less in width, and a plate with bottom title should be 7
+inches or less in depth. In other words, the actual depth and width
+of a single-page plate in a page of any size must depend on the number
+of lines in its title, the inclusion of which should not extend the
+matter much, if any, beyond the dimensions given in the table. A
+difference of 1 inch or less in the width of a folding plate may
+determine whether it must be folded once or twice, so that by
+consulting this table an author may save expense in binding and
+promote the reader's convenience in handling the plate.
+
+A text figure (including the title) can not extend beyond the text
+measure but may be of any size or shape within that measure, as shown
+on Plate I, figures 4, 8, 9, 10.
+
+
+SUBDIVISIONS OF PLATES AND FIGURES.
+
+If a plate consists of two or more parts or photographs each part
+should be marked with an italic capital letter--=A=, =B=, etc.--which
+should be placed directly under each. If it is made up of many parts,
+in the form of plates that accompany reports on paleontology, each
+part should be similarly marked with an arable numeral--1, 2, 3, etc.
+If a text figure is subdivided into two or more parts, each part
+should be marked with a roman capital--A, B, C, etc.; and if details
+of a part are to be described each detail should be marked by an
+italic lower-case letter--a, 6, c, etc.
+
+
+
+
+PREPARATION OF COPY BY AUTHORS.
+
+
+CHARACTER OF ORIGINAL MATERIAL.
+
+In the Geological Survey, as elsewhere, the "originals"--that is, the
+original material submitted by authors for the illustration of their
+reports--differ greatly in character and in degree of clearness. Some
+are carefully prepared; others are rough, obscure in part, and
+defective in detail. Drawings made from poor originals progress
+slowly, because the draftsman spends much time in interpreting
+uncertain features or in conference with the author concerning
+details. An original should be perfectly clear in detail and meaning,
+so that the draftsman can follow it without doubt. It should not
+consist of parts that must be brought together to make a new drawing,
+because the result of the combination of the parts will be uncertain
+at the outset and may not prove satisfactory. Each original
+illustration should be prepared with the idea that the draftsman who
+will make the finished drawing will be unfamiliar with the subject and
+will need definite instructions; all data should be plotted and each
+figure or plate should be completely made up before it is submitted.
+More or less roughly prepared originals are expected, but they should
+show no uncertainty in details. Obscure features may be cleared up by
+inclosing the features in penciled loops connected by a line with
+notes written on the margin, such as "omit this line," "turn at an
+angle of 30° from true north," "add," "cut out."
+
+
+PRELIMINARY PREPARATION OF MAPS.
+
+The base map that generally accompanies a report may be an original
+field sheet or it may have been compiled from various sources by an
+author and made to incorporate the results of his field work. It
+should not be a collection of maps of different scales and standards
+to be worked into a new map.
+
+The source of the data shown on every original base map should be
+indicated on the map, whether it is to be used as an illustration or
+as a record of field work. This information is required as a permanent
+record for showing the reliability of the map, for use in comparing
+data, and for giving full credit to those who are responsible for the
+data. An author should see that this requirement is observed in order
+that proper credit may be given and should especially see that all
+cooperative agreements and organizations are properly mentioned.
+
+An original map should preferably be complete in itself. It should not
+consist of several parts or sheets unless the data to be represented
+are unusually complex. All elaborate or technical finish of border
+lines, lettering, or like features should be left to the draftsman or
+the engraver.
+
+Base maps that involve the compilation of new data should be prepared
+by either the topographic branch or the division of Alaskan mineral
+resources. If a base map already published is to be reused it should
+be submitted to the chief topographic engineer or to the chief of the
+division of Alaskan mineral resources for approval. This procedure
+will insure a single standard of geographic accuracy in maps appearing
+in Survey publications.
+
+A geologist who requires a base map that includes new topographic data
+should address a request for its preparation to the chief geologist,
+who, through the Director, will refer the request to the topographic
+branch. The request must be accompanied by a full statement regarding
+the proposed report and the time when it is likely to be submitted.
+The preparation of such base maps by draftsmen in the division of
+geology, the land-classification board, the water-resources branch, or
+the section of illustrations has been discontinued except for the
+minor adaptations provided for above.
+
+If a report requires the preparation of a base map that includes no
+new topographic data such a map must be compiled from other authentic
+maps by the division or branch in which the report originates. If,
+however, no draftsmen are available in that division or branch, an
+arrangement can be made with any other branch--as the topographic or
+publication branch--that may have draftsmen available, with the
+understanding that the cost of the work shall be reimbursed to the
+branch doing the work by the branch ordering it. For indicating
+geologic and other data, however, an author may make use of an
+authentic base map already published, and after it is reduced or
+enlarged to appropriate scale by photography such a map may suffice
+for transmittal with a manuscript.
+
+
+MATERIAL AVAILABLE FOR BASE MAPS.
+
+The maps already published by the Geological Survey[2] and other
+Government bureaus should always be consulted when a new base is to be
+compiled. The following list includes most of the maps available:
+
+1. The Survey's regular topographic atlas sheets, published on three
+scales--15-minute sheets, scale, 1:62,500; 30-minute sheets, scale,
+1:125,000; 60-minute sheets, scale, 1:250,000--approximately 1 mile, 2
+miles, and 4 miles to 1 inch, respectively--and its "special" maps,[2]
+some of which are published on other scales. All these maps can be
+used as bases for detailed geologic maps, for compiling maps on
+smaller scales, and for revising other maps.
+
+2. The United States part of the international map of the world, now
+being published on the scale of 1:1,000,000 (approximately 16 miles to
+1 inch). Each sheet of this map represents an area measuring 6° of
+longitude and 4° of latitude. The published sheets of this map may be
+used as bases for general maps. The sheets are drawn on the scale of
+1:500,000, and photolithographs on this scale are available for use as
+bases for geologic or other maps.
+
+The adaptability of the 1:1,000,000 scale map to use as a base for
+general geologic maps is shown in the geologic maps of the southern
+peninsula of Michigan and of Indiana in Monograph 53 (Pls. IV and
+VII), the map of Florida in Bulletin 60 (Pl. I), and the map of
+Vermont in Water-Supply Paper 424 (Pl. I).
+
+3. The Survey's two-sheet wall map of the United States, 49 by 76
+inches, scale 1:2,500,000 (approximately 40 miles to 1 inch). Parts of
+this map can be used as bases for general geologic or other maps and
+as copy for index and other small diagrammatic maps. This map is
+published both with and without contours.
+
+4. Land Office maps and township plats. These maps are now being
+published on a scale of 12 miles to 1 inch; they are also
+photo-lithographed on one-half that scale, or 24 miles to 1 inch. The
+township plats are printed on a scale of one-half mile to 1 inch. The
+maps are especially useful in compiling maps in which land lines
+(townships and sections) are essential, and the township plats afford
+valuable detail and are useful in field work and in revising other
+maps. Township and section lines should appear on all
+land-classification maps published by the Survey. On maps on a scale
+less than 1:250,000 only the townships should be shown; on maps on
+scales greater than 1:250,000 the sections should be shown; on maps on
+a scale of 1:250,000 the sections should be shown, unless their
+representation will materially impair the legibility of the map, in
+which case only the townships should be shown. (See fig. 1.)
+
+5. Post-route maps, covering single States or groups of adjacent
+States, published on sheets of different sizes and on scales
+determined mainly by the size of the State. The map of Texas is
+published on a scale of 12 miles to 1 inch, that of Virginia on a
+scale of 7 miles to 1 inch, and that of West Virginia on a scale of 6
+miles to 1 inch. Both the Land Office and the post-route maps are
+useful for reference in compiling maps on smaller scales. Post-route
+maps are especially useful for comparing and verifying the location of
+cities, towns, and railroads.
+
+6. Coast and Geodetic Survey charts, published on scales that are
+governed by the area represented and the amount of detail to be shown.
+These maps should always be used in compiling and correcting coast
+lines.
+
+7. Maps and charts published by the Corps of Engineers of the Army,
+the Mississippi River Commission, the surveys of the Great Lakes, and
+the boundary surveys. These maps are especially useful if the scale of
+the map to be compiled requires considerable detail.
+
+8. The Survey's three small base maps of the United States--(_a_) a
+map 18 by 28 inches, scale 110 miles to 1 inch, which is published
+both with and without contours, or with relief or hypsometric shading;
+(_b_) a map 11 by 16 inches, scale 190 miles to 1 inch; (_c_) a map
+7-1/2 by 12 inches, scale 260 miles to 1 inch, designed for use as a
+two-page illustration in a bulletin or a water-supply paper.
+
+9. The Century, Rand McNally & Co.'s, Cram's, Stieler's, The Times,
+Johnston's Royal, and county atlases.
+
+10. State and county maps.
+
+11. Railroad surveys, which are useful in furnishing data for
+elevations as well as for locations of towns and stations.
+
+12. The latest national-forest maps and proclamations. It is, however,
+not necessary that national forests, bird reservations, and national
+monuments be shown on a map in a report unless their addition is
+specially requested by the author or by the chief of the branch
+submitting the report, and they should not be shown if they will
+obscure other more important data.
+
+[Footnote 2: See "Topographic maps and folios and geologic folios
+published by the United States Geological Survey" (latest edition).]
+
+[Illustration: Figure 1.--Diagrams showing principal, guide, and
+auxiliary meridians, standard and special parallels and correction
+lines, and system of numbering townships, ranges, and sections.]
+
+The Survey has published numerous maps of parts of Alaska, as well as
+other maps, which are available for use or reuse in its reports.
+Copies of all base maps for which copper plates have been engraved by
+the Survey can be obtained on requisition, and their use in a new
+report will save time as well as the cost of engraving. Other maps
+will be found in the Survey library, where the latest editions only
+should be consulted.
+
+
+BASIC FEATURES OF MAPS.
+
+It must be remembered that "every map, whatever its scale, is a
+reduction from nature and consequently must be more or less
+generalized."[3] The degree of generalization in the geologic and
+other detail to be shown on a map usually involves a corresponding
+degree of generalization in its base. Absolutely true generalization
+means the same degree of omission of detail for each kind of feature.
+If a base map on a scale of 1 mile to 1 inch, prepared with the usual
+detail, were placed before a camera and reduced to a scale of 16 miles
+to 1 inch, the lines representing the smaller tributaries of streams
+and the smaller water bodies, as well as many other features, would
+probably be so greatly reduced in length as to be illegible. If from
+this reduced photograph a new map were prepared, from which all
+features not plainly discernible were omitted, the new map should
+represent what might be called true generalization. This degree of
+generalization is, however, not practicable, but unessential detail
+should be systematically omitted. The amount of detail which a base
+map should show is limited by its scale, by the character of the
+country it represents, and by the kind of data to be shown. Coordinate
+features of a topographic map should be shown with equal detail.
+Detail in culture may call for detail in drainage, though relief may
+be greatly generalized or entirely omitted; detail in relief may
+like-wise call for detail in drainage, though culture may be more
+generalized.
+
+[Footnote 3: Gannett, Henry, A manual of topographic methods: U. S.
+Geol. Survey Mon. 22, p. 107, 1893.]
+
+If the three fundamental features of a topographic map--the culture,
+the drainage, and the relief--are to be engraved or photo-lithographed
+separately and printed in colors, the best results can be obtained by
+drawing each feature in a separate color on one sheet unless the work
+is coarse and great precision in register is not needed. The culture
+should be drawn in black waterproof ink, the drainage in Prussian
+blue, and the relief in burnt sienna; but care should be taken that
+the colors used will photograph well. To insure a good photograph it
+is usually necessary to add a little black to the blue and brown. (See
+"Inks," p. 25.) The photographer will then make three negatives and
+will opaque or paint out all but one of the three features on each
+negative. The cost is somewhat greater than that of reproducing three
+separate drawings, but the result gives more accurate register than if
+the drawings were made on separate sheets, which are likely to change
+in size before they are reproduced.
+
+
+STANDARD SCALES.
+
+The standard scales of the maps used in the publications of the
+Geological Survey are fractions or multiples of 1:1,000,000 (see p.
+14), except for a map that is reduced expressly to fit one or two
+pages of a report or that is reduced horizontally or vertically to fit
+the text as a small diagrammatic or index map. It should be remembered
+that a map which may be serviceable for use in compiling a new map,
+except as to scale, can be reduced or enlarged to the scale of the new
+drawing by photography, by a pantograph, or by other means. (See p.
+47.)
+
+Maps compiled by an author should be prepared on a scale of at least
+1-1/2 times and preferably twice the size of the scale used on the
+published map. Maps traced on linen should be no less than twice the
+size of publication. Not only is the quality of the reproduction
+improved by considerable reduction, but the larger scale of the
+drawing facilitates the plotting of details. It should be remembered,
+however, that a linear reduction of one-half produces a map only
+one-fourth the area of the original, and reduction so great may
+prevent the addition of data, such as an extended note in small
+letters applying to a small area on the face of a map, which would not
+be legible when reduced.
+
+
+ORIENTATION OF MAPS.
+
+A map that bears no arrow indicating north is supposed to be oriented
+north and south, and its title should read from west to east. If,
+however, the area mapped has a general trend in one direction, as
+northwest to southeast, and its squaring up by a north-south line
+would leave too much blank paper, this general rule is not followed.
+The border lines on such a map should conform to the general trend of
+the area mapped, an arrow should show north, and the title and scale
+should be placed horizontally, but the projection numbers and town
+names should follow the direction of the parallels of latitude. (See
+Pis. X and XII, Bull. 628; and Pis. VI, XV, and XVI, Mon. 52.)
+
+
+PROJECTION.[4]
+
+[Footnote 4: See also pp. 43-45, where the method of projecting a map
+is more fully explained.]
+
+The polyconic projection has been adopted by the Geological Survey for
+its topographic atlas sheets and must be consistently used for its
+other maps. If a new map is to be compiled an accurate projection
+should first be constructed, and no plotting should be done on it
+until the projection has been checked and found to be correct. A
+projection should be checked or proved by some one other than the
+person who prepared it. Next the drainage and the water areas should
+be outlined; then the cultural features should be added; and finally
+the relief, whether expressed by contour lines, hachures, or
+shading.[5]
+
+[Footnote 5: See pp. 49-48 for methods of tracing and transferring.]
+
+
+EXPLANATION.
+
+Under the heading "Explanation" should be placed all matter needed to
+describe fully the details of an illustration, whether map, diagram,
+or section, so that if the illustration became detached it would be a
+complete self-explanatory unit.
+
+The explanation of a map may be placed inside the border lines if
+there is ample room for it, or it may be placed outside. The standard
+arrangement for an outside explanation for geologic maps is shown, in
+the geologic folios, which should be followed in general form. If
+there is space within the border lines the explanation may be
+appropriately arranged therein, either in a vertical column or
+horizontally, according to the size and shape of the space available.
+If the sequence of formation is shown by horizontal arrangement the
+younger formations are placed at the left and the older at the right.
+If it is shown by a vertical arrangement the youngest formation is
+placed at the top.
+
+Each original map submitted by an author should have at least 4-1/2
+inches of blank margin on the right and at the bottom in which to
+place the explanation, scale, title, and other matter, but the author
+should make no attempt to elaborate these features nor should he
+employ a draftsman to letter them carefully. Plainly written ordinary
+script is quits sufficient for original maps; the final lettering,
+which may consist entirely of impressions from type, will be added
+after submittal of a report.
+
+
+TITLES OF MAPS AND OTHER ILLUSTRATIONS.
+
+The titles of maps should be supplied by authors but are subject to
+revision in order to make them agree with established forms. They
+should be written in ordinary script, not carefully lettered. They
+should state concisely the kind of map, the area shown, the special
+features represented, and the county, State, or Territory in which the
+area is located. (See p. 58.) Titles are reproduced directly only on
+lithographs, three-color prints, photogelatin plates, and other
+illustrations that are printed by contractors, not by the Government
+Printing Office. The titles of illustrations that are reproduced by
+relief processes, such as zinc etching, half tone, and wax engraving,
+are printed at the Government Printing Office from type, and proofs
+are submitted to the authors for examination.
+
+
+SYMBOLS USED ON MAPS.
+
+GENERAL FEATURES.
+
+More than 200 symbols have been used on maps to express 25 different
+kinds of data, a fact indicating at once a notable lack of uniformity
+and a need of standardization. It is of course impossible to provide a
+characteristic symbol that can be used uniformly for each kind of
+feature, and therefore the same symbol may be used on different maps
+to express different things. The symbols shown in Plate II are those
+most used on geologic maps. The symbols for dip and strike, fault
+lines, mine shafts, prospects, and several others are generally well
+known, but on some maps it may be necessary to modify a standard
+symbol to express additional distinctions. The symbols shown, however,
+will cover all the ordinary requirements of miscellaneous mapping.
+Though the plate shows more than one symbol for some features the
+symbol most commonly used is given first and should be preferred. The
+center of each symbol should mark the location of the feature
+symbolized. Symbols are not always platted with sufficient care. On
+small-scale maps they are difficult to locate and unless great care is
+taken in platting them they are likely to be several miles out of
+place. All symbols should be located precisely where they belong.
+
+The symbol showing dip and strike should be accurately platted by
+means of a protractor, so that the strike will be shown graphically,
+without a number and a degree mark, and not need replatting by a
+draftsman or engraver. The dip, however, should be indicated by a
+number and a degree mark.
+
+LETTER SYMBOLS.
+
+The letter symbols used on most geologic maps to indicate the ages
+and names of the formations represented consist of two or more
+letters--an initial capital letter for the name of the system and
+one or more lower-case letters for the name of the formation or of
+the material, as Qt (Quaternary--lower terrace deposits); Cpv
+(Carboniferous--Pottsville formation); COk (Cambrian-Ordovician--Knox
+dolomite), etc. The standard usage for this feature is shown in the
+geologic folios but is subject to modification in other publications.
+
+In preparing an original geologic map a letter symbol, such as has
+been just described, or a number should be put in the proper place in
+the explanation, and the same symbol or number should be repeated at
+one or more places on the map within the areas to which it refers.
+Each area that is indicated by a color should be marked with the
+proper symbol in order to make its identification sure, for light
+colors especially are likely to fade and mixed colors can not be
+discriminated with certainty.
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE II
+
+
+SYMBOLS USED ON GEOLOGIC MAPS, ECONOMIC MAPS AND MINE PLANS]
+
+OIL AND GAS SYMBOLS.
+
+A complete set of symbols for maps showing oil and gas is given on
+Plate II. Referring to these symbols the chief geologist, in a
+memorandum to the Director, writes:
+
+ The symbols used by the Survey in its oil and gas maps have
+ not been in accord with those used by the oil companies, nor
+ have they been wholly logical. It appears that though they
+ were submitted for recommendation they never have been
+ formally approved.
+
+ Herewith I submit a code prepared by the geologists of the
+ oil and gas section. They conform largely to commercial use
+ and embrace its best features as well as the best and most
+ logical features of our previous usage, the departures from
+ which are, after all, of minor consequence.
+
+ The symbols here submitted [see PI. II] with recommendation
+ for approval are founded on a building-up system, so that the
+ history and the results of drilling at any location can be
+ recorded by slight additions to symbol and without erasure.
+ Thus maps may be revised without scratching.
+
+ In drawing these symbols the draftsman should make the rays
+ of the gas well distinct and in adding the vertical bar or
+ line showing that a hole is dry or abandoned should make it
+ long enough to be distinct. It would be preferable to draw
+ this bar obliquely, but an oblique position would coincide
+ with some of the patterns on certain maps, and it should
+ therefore be placed vertically. The vertical line indicates
+ the failure or abandonment of the well, the symbol for which
+ Is thus scratched off or canceled by the line drawn through
+ it. The symbols agree so far with commercial usage that oil
+ men will have little need to consult the explanation.
+
+SYMBOLS FOR USE ON MAPS SHOWING FEATURES OF GROUND WATER.
+
+The symbols used on maps relating to ground water represent the
+features named below, each of which has been shown in publications
+already issued.
+
+ Area of absorption or outcrop. Area that discharges ground water.
+ Depth to water table. Quality of ground water.
+ Contours of water table. Area irrigated with ground water.
+ Fluctuation of water table. Nonflowing well.
+ Depth to water-bearing formation. Flowing well.
+ Structure contours of water-bearing Unsuccessful or dry well,
+ formation. Well with pumping plant.
+ Area of artesian flow. Spring.
+ Head of artesian water.
+
+The lack of uniformity in the symbols commonly employed to represent
+these features is due to differences in the number of color on the
+maps and differences in the scale. Standard colors for the larger
+features, such as those for areas of artesian flow, areas of
+absorption, and curves showing depths to water table or to
+water-bearing formations, can not be fixed, because of considerations
+of economy in printing. For example, if light green is the standard
+color to be used for delineating areas irrigated by ground water and
+no green is used on other parts of the map its use would represent an
+additional or special printing, whereas a tint of blue, brown, or
+purple, if any of these colors is used for other features on the map,
+might be used also for this feature without additional printing.
+Therefore the general use of any particular color for a water feature
+seems to be impracticable; but this fact should not preclude the
+adoption of color standards for use subject to the requirements of
+economy in publication.
+
+The ordinary symbols for wells are the open circle and the solid
+circle, or dot. Only in the secondary or specific well symbols does
+there appear to be lack of uniformity, the choice of secondary symbols
+being governed either by personal preference or by the requirements
+for specific distinction.
+
+All symbols should, if possible, suggest the things they represent.
+Wells are circular and hence the open circle is most used and most
+appropriate for nonflowing wells. To indicate a flowing well the
+circle is made solid, denoting that the well is full of water. For an
+unsuccessful well the most suggestive symbol would be an open circle
+with a line drawn through it to denote cancellation. It has been
+suggested that if water features, including wells, are to be printed
+in blue, unsuccessful wells, or dry holes, be printed in black. A
+large circle drawn around the symbol for a flowing or nonflowing well
+will appropriately denote a pumping plant at the well.
+
+The accepted symbol for a spring is a dot with a waved tail
+representing the direction of flow, if known. This symbol can not be
+modified without destroying its prime characteristics, but it may be
+accompanied by a letter indicating the kind of spring. An open circle
+with a tail might be used on large-scale maps, but it would be out of
+scale on other maps, whereas the black or blue dot and tail will fit
+maps of any scale.
+
+The following colors and symbols can most appropriately be used to
+represent ground-water features. The well and spring symbols can be
+varied by adding letters if they are necessary to express other data
+than those indicated in the list below.
+
+_General ground-water features._
+
+ Area of absorption or outcrop: Flat color used on the map to
+ show the geologic system in which the absorbing formation
+ occurs.
+
+ Areas showing depths to water table: Shades of purple and gray;
+ if possible the shades showing the areas of least depth
+ should be darkest and the shades should grade from those to
+ lighter tints.
+
+ Contours of water table, or contours on water-bearing
+ formations: Gray or purple curves or lines.
+
+ Areas of artesian flow: Blue flat tint, or fine ruling in blue.
+ Depth to water-bearing formations: Gradation of a single
+ color or of two related colors from dark for shallow depths
+ to light for greater depths.
+
+ Nonflowing artesian areas (pumped wells): Green flat tint, or
+ fine ruling in green. Depth to water-bearing formations shown
+ by gradation of tint if possible from dark for shallow depths
+ to light for greater depths.
+
+ Head of artesian water: Blue curves or lines.
+
+ Areas that discharge ground water: Blue flat tint, or fine
+ ruling in blue.
+
+ Areas irrigated with ground water: Green flat tint, or fine
+ ruling in green.
+
+ [Illustration] Well, character not indicated. [Illustration]
+ Well, nonflowing. [Illustration] Well, flowing.
+ [Illustration] Well, unsuccessful or dry. [Illustration]
+ Well, nonflowing, with pumping plant [Illustration] Well,
+ flowing, with pumping plant. [Illustration] Springs.
+ [Illustration] Spring, thermal. [Illustration] Spring,
+ mineral.
+
+The standard color scheme should be used if no conditions preclude its
+use, but if other colors can be used with greater economy without
+sacrificing clearness the use of the standard colors should be waived.
+
+
+BLACK-LINE CONVENTIONS.
+
+A complete set of the black-line patterns used to distinguish areas on
+a map is given in Plate VIII (p. 60), and their application to a
+finished drawing is shown in figure 9 (p. 62). These patterns,
+however, should preferably not be used by the author in his
+preliminary work on an illustration. For this purpose water colors or
+colored crayons are preferable, and the distinctions between areas may
+be emphasized by letter symbols.
+
+
+MATERIALS USED IN PREPARING MAPS.
+
+PAPER.
+
+For large and important maps which may at some time be extended to
+cover a greater area or which may be made to fit maps already prepared
+or published the paper used should be mounted on muslin to reduce to a
+minimum the shrinking or stretching caused by atmospheric changes.
+Pure white paper produces a better negative than a cream or yellowish
+paper and will retain its color longer, but all papers become more
+yellow with age and exposure to light.
+
+The following brands of paper are used in the Survey in the
+preparation of maps:
+
+"Normal" K. & E., unmounted. Has an excellent surface and comes in
+flat sheets, 19 by 24, 22 by 30, and 27 by 40 inches.
+
+"Paragon" K. & E., mounted on muslin. In 10-yard rolls 72 inches wide.
+Used in the Survey for large office drawings and maps of large scale.
+
+"Anvil" K. & E., mounted on muslin. In 10-yard rolls 42, 62, and 72
+inches wide. Used in the Survey for large drawings.
+
+"Whatman's hot pressed," unmounted or mounted on muslin. In sheets
+ranging in size from 13 by 17 to 31 by 53 inches. An excellent paper
+for maps. The muslin-backed paper is recommended for use in preparing
+large detailed maps and base maps that are to be retained as permanent
+records. The muslin provides a durable and flexible backing that
+permits the map to be rolled, and paper thus mounted is particularly
+serviceable for a map which may be subjected to considerable revision
+and to which must be added finally a title, explanation, and other
+marginal matter.
+
+"Ross's relief hand-stipple drawing paper." A stiff enameled or
+chalk-coated paper whose surface has been compressed into minute
+points that stand in slight relief so that a shade made on it with
+pencil or crayon is broken up into dots and can be reproduced by
+photo-engraving. For use in making shaded drawings, drawings showing
+relief by light and shade, etc. Similar paper is prepared for
+parallel-line and other pattern effects. In sheets ranging in size
+from 11 by 14 to 22 by 28 inches. (See p. 51 for method of using.)
+
+Profile and cross-section paper. In sheets of convenient sizes or in
+rolls. Bears lines printed in blue, green, red, or orange, in many
+kinds of rulings, which may be selected by reference to catalogues.
+Profile and cross-section paper printed in orange is recommended for
+preliminary drawings; blue is recommended for drawings that are made
+in pencil and submitted for inking in.
+
+BRISTOL BOARD.
+
+For the smaller maps, such as key maps and maps less than 18 by 24
+inches, and for small drawings made for direct reproduction,
+Reynolds's bristol board is recommended on account of its pure-white
+color and its hardness, which permits erasures to be made without
+affecting redrawing over the corrected area. It is obtained in 2-ply,
+3-ply, and 4-ply sheets. The 2-ply and 3-ply are especially useful in
+making delicate brush and pencil drawings and pen and ink drawings.
+The sizes used in the Survey are 16-1/2 by 20-3/4, 18-1/4 by 22-3/8,
+and 21-1/2 by 28-3/4 inches.
+
+TRACING LINEN.
+
+Tracing cloth or linen is especially useful for large work that will
+require considerable reduction. (See p. 18.) Its advantages are that a
+tracing that has been carefully made on it over any kind of copy for
+direct reproduction by a photo-engraving process can be used for
+making a paper negative for contact printing or blue printing. On the
+other hand, it is susceptible to atmospheric changes that affect
+scale, and the lines traced on it are not reproduced as sharply as
+those made on paper. It can be obtained in rolls 30 to 54 inches wide.
+
+Erasures should be made on tracing linen with a hard rubber eraser,
+not with a sand rubber or a steel eraser.
+
+INKS.
+
+The best drawing inks are in liquid form, ready for use. They should
+be waterproof and equal to the grade known as Higgins's waterproof
+ink. When a suitable waterproof blue ink can not be obtained, a good
+blue for features of drainage can be made by dissolving a half pan of
+Winsor & Newton's prussian blue in water. No good waterproof burnt
+sienna ink seems to be obtainable, but a good substitute can be made
+by dissolving Winsor & Newton's water color of that name.
+
+Ink lines should be drawn in full strength of color--lines that should
+be black must not appear grayish, for example--and pens should be kept
+clean. The same pen should not be used for applying two inks, as the
+mixture thus produced is likely to thicken or coagulate on the pen. A
+little black should be added to colored inks that are used in making
+drawings to be reproduced in colors in order to strengthen the lines
+for photographic reproduction.
+
+DRAWING PENS.
+
+The pens made by Keuffel & Esser, especially their No. 3202, and
+Gillott's Nos. 291, 290, 170, and 303 give complete satisfaction. The
+Gillott numbers are given in the order of fineness of the points. No.
+291 being the finest. The best cleaner for a drawing pen is a piece of
+chamois skin.
+
+PENCILS.
+
+Pencils used for drawing should have leads of a quality equal to those
+of the Koh-i-noor brand, in which the grades of hardness are indicated
+by 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, and 9H; the
+softest grade is 3B and the hardest 9H. The grades most generally used
+are B, HB, F, 4H, and 6H.
+
+RUBBER ERASERS AND CLEANERS.
+
+Two kinds of rubber erasers are usually employed in making erasures on
+drawings--a hard, dense rubber like the "Ruby," and a soft, pliable
+rubber like the "Venus" or "H" (Hardtmuth). The soft rubber is also
+useful for cleaning large surfaces. Art gum is also recommended for
+this purpose and has the advantage of not disturbing the surface of
+the paper.
+
+COLORED PENCILS AND CRAYONS.
+
+Colored pencils and crayons are useful only for coloring preliminary
+maps. They are not recommended for use on maps that are to be kept for
+reference or to be submitted for reproduction, because the colors rub
+off, but they can be used on photographic prints of base maps or on
+transparent oversheets, for which the unglazed side of tracing cloth
+is well suited. When they are so used register marks should be added
+at numerous points on the map and the oversheet, including the four
+comers, the color boundaries should be drawn or traced, and finally
+the colors should be added. Two or more colors should not be used on
+any one area to modify a tone, but each area should be colored with a
+separate crayon. Patterns or designs should not be used except to
+strengthen contrasts, and for that purpose a pattern may be drawn with
+a black pencil over a color.
+
+WATER COLORS.
+
+By dilution to half strength some of the standard water colors will
+yield a tint or hue that will contrast with other tints or hues
+produced in the same way quits as well as undiluted or full colors
+will contrast with one another. The colors named below, except
+chrome-yellow and emerald-green, are among those that when diluted
+will afford satisfactory contrasts among themselves and with their
+full colors and are recommended for use in coloring original maps.
+
+Mauve. Hooker's green No. 2.
+Crimson lake. Emerald-green.
+Orange-vermilion. Payne's gray.
+Burnt sienna. Lampblack.
+Cadmium-yellow. Sepia.
+Chrome-yellow. Cerulean blue.
+Olive-green.
+
+Other pigments spread better than cerulean blue and emerald-green, but
+the exceptional purity of color of these two seems to warrant their
+use.
+
+JAPANESE TRANSPARENT WATER COLORS.
+
+Japanese transparent water colors, so called, are used by some
+geologists. They spread evenly and are convenient for field use, but
+they can not be washed out like other water colors, so that when they
+are once applied to an area and a change of color becomes necessary
+they must be bleached out. A good bleach is sodium hypochlorite, which
+should be applied with a brush until the color disappears, and the
+area dried with a blotter before recoloring. Light tints of these
+colors are believed to be somewhat fugitive if exposed to strong
+light.
+
+COLORING GEOLOGIC MAPS.
+
+The colors used on most original maps are not pleasing, a fact that is
+of no particular importance, but--and this is of importance--they
+often fail to give clear distinctions; the separate areas can not
+always be identified or distinguished with certainty. Again, some
+colors are fugitive, and when laid on in light tints they disappear
+entirely or become uncertain. Much of the difficulty in identifying
+and discriminating colors on an author's original maps is due to the
+promiscuous mixing of colors. Many persons can not match or
+discriminate mixed or broken colors. Hence if the supply of a color
+produced by mixing becomes exhausted and the attempt is made to
+duplicate it by a second mixture the two will probably fail to match.
+It is therefore suggested that colors in full strength and colors
+diluted to half strength be used instead of mixtures of two or more
+pigments, so that one color in two strengths or tones can be employed
+to indicate areas that are to be distinguished. The colors listed on
+page 26 will give 24 satisfactory distinctions and will thus supply
+all demands for map coloring.
+
+To insure satisfactory contrasts between colored areas on a map,
+unlike colors should be placed next to each other--that is, colors
+should be placed together that are widely separated in the spectrum,
+such as yellow and mauve, red and green, blue and orange, burnt sienna
+and olive-green; not such as red and orange, blue and purple, orange
+and yellow, sepia and burnt sienna.
+
+A sufficient quantity of water and color pigment to be used for one
+formation area on a map should be stirred in a saucer until the
+desired tint is produced before it is applied. To maintain the same
+tone properly the color should be well stirred every time the brush is
+filled; if it is not stirred the brush will on the next dipping take
+up a lighter tint, because most pigments, especially those derived
+from minerals, tend to precipitate. When the colors are applied the
+map should preferably be placed in a slightly inclined position, and
+the coloring should be started at the upper boundaries of an area to
+be colored, the well-filled brush being pulled toward the painter and
+Worked rapidly back and forth horizontally, the edges of the fresh
+color being kept wet. If the edges are allowed to dry, a hard line and
+a smeared or uneven effect will be produced.
+
+A strong color should generally be used for small areas unless the map
+shows also large areas that must have the same color; lighter hues
+should be used for large areas. Bright colors are best suited for
+areas of igneous rocks, dikes, and veins, and these may be reduced in
+strength for the larger areas.
+
+The Survey's color scheme (see p. 63) need not be applied at this
+stage of preparation, except in the most general way. Appropriate
+final colors can be best selected when the new map is made ready for
+engraving. In the author's original maps adequate color distinctions
+between areas are more important than the use of standard geologic
+colors. Patterns should not be ruled in one color on an original map
+to indicate distinctions between different formations of the same age
+or period, because such patterns are difficult to produce by hand with
+proper uniformity except by engraving.
+
+It is of vital importance that an original base map should be free
+from colors and from technical symbols in order that it may be kept
+clean for photographing and preserved for possible future use. Such a
+map should preferably be photographed in order to obtain prints on
+which to add the colors and symbols; the use of an oversheet for this
+purpose is not nearly so satisfactory. When photographed a base map
+should be reduced to publication scale in order to save the additional
+cost of a larger negative, and this reduced map may be made up for
+publication by the addition of colors and symbols, title, explanation,
+etc.; but the lithographer will also need the original base map from
+which to make his reproduction.
+
+
+DIAGRAMS.
+
+ESSENTIAL FEATURES.
+
+The term "diagrams," as used here, includes such illustrations as mine
+plans, profiles, sections, stereograms, and maps that are more
+diagrammatic than cartographic. The first essential in the original
+drawings for simple diagrams is clearness of copy. Simplicity of
+subject does not warrant hasty preparation, for an original sketch
+that has been carelessly drawn and is inaccurate or inconsistent in
+detail may lead to serious errors. Ruled paper printed especially for
+platting profiles and cross sections should be used. Curves or graphs
+made by an author with pencil on blue-lined section paper may be inked
+by more skillful draftsmen. An author's pencil sketches are usually
+satisfactory if they indicate plainly the facts to be represented, but
+they should be prepared with some care as to detail. Tables and like
+matter are not generally satisfactory material from which to prepare
+drawings. In drawings for diagrams that are to be printed in the text
+as figures the use of large, solid black bars or of conspicuous areas
+of solid black is objectionable, because the black is likely to print
+gray and to appear uneven in tone. Ruled tints or cross lining give
+better effects. Stereograms should be prepared by an author with
+especial care, for they represent facts only as the author sees them,
+and the author's view must be imparted to the draftsman graphically.
+The "third dimension"--the relief--in such drawings is not easily
+expressed and should be brought out clearly in the author's rough
+sketches.
+
+For illustrations of apparatus photographs are preferred, but if rough
+sketches are submitted they should show not only correct relations but
+all dimensions.
+
+PLANS OF MINE WORKINGS.
+
+Blue prints obtained from mining companies are acceptable for plans of
+mines or underground workings, but all unnecessary or irrelevant
+details on such plans must be canceled and all essential features
+retained, and every essential feature, especially any added data, must
+be clearly interpretable. Many such blue prints are so large and
+unwieldy that they must be greatly reduced by photography before they
+can be redrawn. If the lines are too weak to photograph, a tracing of
+the essential parts can be made and reduced to about twice publication
+size. The shadowless drafting table, described on pages 47-48, is well
+adapted to the work of making such tracings. Blue prints can also be
+pantographed to any convenient size if the details are not too minute
+or complex.
+
+[Illustration: Figure 2.--Conventional lines used in preparing plans
+and diagrams of mine workings to distinguish different levels.]
+
+The levels in plans of underground workings can be differentiated in
+finished drawings by a system of conventional outlines in black, as
+shown in figure 2, by conventional patterns or symbols within plain
+outlines, or by colors. Such plans should not be printed in colors
+unless the maze of workings is so complex that lines showing the
+different levels would become confused or obscure if printed in black.
+
+SECTIONS.
+
+The standard forms of geologic sections are shown in the geologic
+folios. Structure sections should be prepared with great care as to
+detail but without attempt at refinement of lines and lettering. The
+author's drawing of a section along a line or zone that is not
+definitely indicated by a line on an accompanying map should be so
+prepared that it may be copied exactly. On the other hand, the
+draftsman, in reproducing a section that represents the structure
+along a given line or zone, may be able to make the outcrops coincide
+with the topography and the formation boundaries shown on the map, but
+the structure, or the interpretation of it to be given, should be
+carefully worked out by the author. All essential facts relating to
+bedding, folding, faulting, crosscutting dikes and veins, or other
+significant details should be indicated with precision. No attempt
+need be made to draw firm, steady lines so long as the essential facts
+are clearly expressed.
+
+All sections should be drawn to scale, and both the vertical and the
+horizontal scale should be given on the drawing. These scales should
+be uniform if possible, or at least the vertical exaggeration should
+be minimized. Too great vertical exaggeration creates distortion and
+is grossly misleading. Sections should be drawn to scale on ruled
+paper prepared for the use of authors. Such paper may be obtained on
+requisition.
+
+[Illustration: Figure 3.--Section and perspective view showing
+relations of surface features to the different kinds of rock and the
+structure of the beds.]
+
+A kind of cross section which is not often used but which gives a
+more pictorial and clearer conception of underground relations than
+other kinds is made by adding a sketch of the topography above the
+section. This sketch should be a perspective view, in which the
+prominent features shown hypothetically in the section below it will
+be reflected in the topography. Such a sketch might show, for example,
+not only monoclinal slopes, "hogbacks" due to steeply upturned beds,
+terraces, escarpments, and like features, but volcanic necks or other
+extruded masses in their true relations to the underground geology of
+the country. (See fig, 3.) In submitting the draft of such an
+illustration the author should, if possible, submit also a sketch or
+photographs of the adjacent country and indicate on the section the
+point of view by notes such as "Sketch A made at this point," "See
+photograph B." The sketch will be more useful if it is prepared on a
+scale consistent with the details of the section. It may be made with
+a pencil and should show as well as possible the relations of the
+features in the landscape to those in the section. Some good examples
+of illustrations of this type can be found in Powell's "Exploration of
+the Colorado River," pages 182-193. One simpler figure of the same
+kind is given on the cover of the geologic folios.
+
+In preparing original drawings representing columnar sections, or
+sections in wells or ravines, the author should indicate all
+well-defined or important local features of structure, such as
+cross-bedding, ore bodies, or lenses. If there are no unusual features
+or details, the subdivisions need be identified only by names of
+materials, such as "thin-bedded limestone," or "slates with some
+coal," the coal beds being shown. The sections should, however, be so
+plotted and subdivided by the author that each section or group of
+sections will be complete in its crude form. The compilation of
+various parts into one unit and the construction of columnar sections
+by reference to tables alone is an essential part of the author's
+original preparation.
+
+[Illustration: Figure 4.--Sections of coal beds. The Figure shows the
+publications size and the arrangement at the sections. Each section
+should be drawn three-tenths or four-tenths of an inch wide and
+reduced one-half. Thicknesses can be indicated by numbers, as shown on
+sections 1 and 10, or by bar scale.]
+
+Sections designed to show the relative thickness of beds of coal,
+arranged in groups for publication either as plates or figures, should
+be drawn in columns three or four tenths of an inch wide and reduced
+one-half, as shown in figure 4. These sections, whether correlated or
+not, should be drawn to some definite vertical scale and should show
+the thickness of the coal beds, preferably by numbers indicating feet
+and inches, the other material being symbolized and the symbols
+explained graphically, as shown in figure 4. The vertical scale should
+always be stated for the use of the draftsman. A bar scale may be
+used instead of figures showing the dimensions of the individual beds.
+
+LITHOLOGIC SYMBOLS.
+
+The symbols used to indicate the various kinds of rocks illustrated in
+sections and diagrams are shown in Plate III. The units or elements of
+these symbols may be spaced more openly in generalized diagrammatic
+sections than in sections that show great detail.
+
+Symbols should be used consistently throughout a report, and in order
+to make them consistent a set showing the symbol to be used for each
+kind of rock to be indicated should be prepared before the original
+drawings are made. Some inconsistencies may be unavoidable on account
+of the small size of some areas shown and the contrast needed between
+others; but the deviations from the set of symbols adopted should be
+minimized.
+
+
+USE OF PHOTOGRAPHS AS ILLUSTRATIONS.
+
+ESSENTIAL FEATURES.
+
+The foundation of a good photographic print is a good negative, and
+the best prints for reproduction as illustrations are those made from
+negatives in which the illumination is evenly distributed and the
+details are sharp--such negatives as are obtainable only by the use of
+small stops and correct focusing. A good print should not present too
+sharp contrasts between its dark and its light parts; if it does, the
+printed reproduction will show a loss of detail in both. Sufficiency
+of detail depends largely on focus, stopping down, and timing;
+brilliancy is the direct result of ample illumination by sun or
+artificial light, without which a photograph will be dull or "flat"
+and generally unsatisfactory for reproduction. Bad weather may prevent
+good field exposures, yet even in bad weather acceptable negatives may
+be obtained by judicious focusing, stopping down, and timing. If a
+negative is overexposed it may be full of detail, but flat and too
+thin to print well. If underexposed it will show no details in its
+lighter parts and the shadows will be black; and a black shadow is
+nothing less than a blemish. Some detail should appear in all shadows
+and in the middle tones, and some should appear in the high lights;
+and a print in which these are evenly developed and in which the
+illumination is distributed uniformly is technically perfect.
+
+Unfortunately not all field photographs are good, so an author must
+select from his collection those which will make the best half tones.
+In making this selection he should of course consider, first, the
+scientific value of the photograph, and next, its pictorial or
+artistic quality, which, though of secondary importance, should
+nevertheless be kept in mind. A feature worthy of illustration
+deserves good pictorial expression; if it is of superior scientific
+interest it should not be represented by an inferior photograph.
+Fortunately, a good, accurate drawing may be made from a poor
+photograph, and a photographic view that has only minor defects can be
+successfully retouched. Photographs that need much retouching should
+generally be larger than publication size, for the effects of
+retouching--brush marks, etc.--will be softened by reduction.
+Photographs that need only slight retouching need not be larger than
+publication size. A photograph can rarely be satisfactorily enlarged
+in reproduction unless it is sharp in detail and requires no
+retouching.
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS. PLATE III.
+
+LITHOLOGIC SYMBOLS USED IN STRUCTURE AND COLUMNAR SECTIONS TO
+REPRESENT DIFFERENT KINDS OF ROCK]
+
+Unmounted prints are always preferable for use in making
+illustrations. A group that is to form a single plate should be placed
+in an envelope bearing the number of the plate and its title, and each
+print of the group should bear a corresponding number, written in
+pencil on its back. The envelope will protect the prints and keep them
+together, and the numbers will identify them. Red ink should not be
+used to mark photographs, as it is likely to penetrate the coating or
+even the fiber of the paper, so that it can not be erased.
+
+If a print is of doubtful quality two copies of it should be
+submitted--one glazed, the other having a dead finish or "mat"
+surface, which is generally preferable if the print must be
+considerably retouched. The best prints for use as illustrations are
+those made on "regular" or "special" semimat velox and glossy haloid
+papers. The author should indicate prints that may be grouped together
+according to their relation geographically or by subject. Generally
+two half tones will be combined on a page, and the list of
+illustrations should be prepared accordingly.
+
+With slight trimming and reduction, three photographs measuring 3-1/4
+by 5-1/2 inches may be made up one above the other to form a full-page
+octavo plate. Four photographs in which the longer dimensions
+represent vertical distances may sometimes be used if they are placed
+sidewise on the page, with side titles.
+
+Some photographs may be reduced to the width of a page by trimming
+instead of by photographic reduction, which may involve loss of
+detail. The author should clearly indicate the extent of such trimming
+as they may bear without loss of essential details. The trimming is
+best done during the final preparation. A line should not be drawn
+across a photograph to mark such trimming, but the position of the
+line or lines should be indicated either on temporary mounts, on the
+backs of the prints, or by a statement, such as "One inch may be cut
+off on right, one-fourth inch on left, and one-half inch at bottom."
+
+COPYRIGHTED PHOTOGRAPHS.
+
+Section 4965 (ch. 3, title 60) of the Revised Statutes, amended by act
+of March 2, 1895 (Stat. L., vol. 28, p. 965), provides that no
+copyrighted photograph may be used without the consent of the
+proprietor of the copyright in writing signed in the presence of two
+witnesses. A penalty of $1 is imposed for every sheet on which such a
+photograph is reproduced without consents, "either printing, printed,
+copied, published, imported, or exposed for sale." An author should
+therefore obtain the written consent of the owner of a copyrighted
+photograph to use it, and the letter giving this consent should be
+submitted with the illustration.
+
+SOURCES OF PHOTOGRAPHS.
+
+Every photograph submitted with a manuscript should bear a memorandum
+giving the name of the photographer or the owner of the negative. If
+the negative is in the Survey's collection that fact should be stated,
+as "Neg. Keith 318." The Survey receives many requests for copies of
+photographs that have been reproduced as illustrations in its
+publications, and replies to these requests will be facilitated if the
+Survey's number or the source of each photograph presented for use as
+an illustration is stated as above on the photograph.
+
+
+LENDING ORIGINAL PHOTOGRAPHS AND DRAWINGS.
+
+A photograph that has been used in making a half-tone cut for a Survey
+report can not be lent, but if the negative is on file a print can be
+furnished at cost; and a Survey drawing that is well preserved can be
+photographed and a print furnished, also at cost. Requests for such
+prints should be addressed to the Director.
+
+UNPUBLISHED PHOTOGRAPHS.
+
+The Survey can not issue a copy of an unpublished photograph except
+upon the written approval or requisition of the person under whose
+name the negative is filed. This requirement does not apply to a print
+needed for official use, nor to a print made from an old negative
+reserved under the name of any present member of the Survey or from a
+negative that has been released by the person under whose name it is
+filed.
+
+Authors using Survey photographs in unofficial publications are
+requested to acknowledge the source of the photograph by adding to the
+printed title such a statement as "Photograph by U. S. Geological
+Survey (David Whits)."
+
+
+SPECIMENS.
+
+GENERAL REQUIREMENTS.
+
+Specimens other than fossils that are to be illustrated in a report
+should be photographed before they are submitted, but the requisition
+for the photographs should be initialed by the chief illustrator, who
+will indicate the kinds of prints needed. Duplicate photographs of the
+specimens should be made up into temporary plates by the author and
+submitted with his other illustrations, the specimens being retained
+subject to call, if needed, when the illustrations are finally
+prepared. Should a colored illustration of a specimen be needed,
+however, the specimen must be submitted with the report, and a
+different kind of print, preferably one made on platinum or other
+special paper, will be obtained by the section of illustrations.
+
+BORROWED AND FRAGILE SPECIMENS.
+
+In submitting specimens to be illustrated an author should call
+attention to those that have been borrowed and to those that are
+fragile. Borrowed specimens will receive first attention, so that they
+may be returned promptly.
+
+TRANSMITTAL OF PALEONTOLOGIC SPECIMENS.
+
+All requests for paleontologic illustrations should be addressed to
+the Director. The letter of transmittal should state the title of the
+paper, the form of publication desired (bulletin, professional paper,
+or monograph), and the status of the manuscript, whether completed or
+in preparation. If the paper is unfinished an estimate of the number
+of illustrations required should be given, and the special reasons for
+prompt preparation should be fully stated. A letter transmitting a
+second or third lot of fossils should refer to the preceding lot or
+lots if all the fossils are to be used in illustrating the same paper.
+
+Fossils that are to be drawn should be sent directly to the section
+of illustrations, but those that are to be photographed and require
+unusual posing or that are extremely delicate and valuable may be sent
+directly to the photographic laboratory to avoid repeated handling.
+Each specimen or, if it is very small, each box or bottle containing a
+specimen should be numbered, and each lot should be accompanied by a
+list giving their names and numbers. Full instructions as to size of
+reproduction, together with sketches showing the point of view
+preferred and any special features to be displayed should also be
+submitted. All specimens that show strong colors and all groups of
+specimens that are not uniform in color will be coated by holding them
+in the vapor of ammonium chloride unless directions to the contrary
+are given by the author of the paper. As it may not be desirable to
+apply this process to soft or fragile specimens or to specimens that
+have been borrowed an author should indicate any specimens that may
+not be so treated. Specimens whose color aids in revealing detail are
+not so coated. If any features of a specimen are unusual that fact
+should be stated so that the photographer and the retoucher may
+perform their work according to the requirements.
+
+MAKING UP PLATES.
+
+Two or more illustrations may be combined to form one plate in order
+to permit easy and close comparison as well as for economy, for if a
+particular illustration is too small to make a full plate and is not
+suitable for enlargement other illustrations that are closely related
+to it may be put on the same plate. The size of the printed page as
+given in the table on page 11 will determine the size of the plate.
+
+In making up plates composed of a number of figures the author should
+endeavor to group related figures together and at the same time to
+observe proper regard for artistic effect, but as figures vary in size
+and shape a grouping according to relations may not be possible in
+some plates. If related figures can not be kept together the larger
+and darker figures should be placed in the lower part of the plate and
+the smaller and lighter above. If a plate consists of one large figure
+and several smaller ones the large figure should be placed below and
+the smaller figures above.
+
+A number designating a figure should be placed immediately below the
+figure, and a series of such numbers should preferably begin with 1 in
+the upper left corner and continue consecutively across and down
+through the plate. This arrangement is not always possible, however,
+on account of variations in the size of figures.
+
+As drawings of fossils or other specimens are prepared separately and
+grouped into plates, and as most paleontologists make up their own
+plates, each in his own way, there is naturally great dissimilarity in
+methods and in results. Ordinary white or light-gray cardboard should
+be used, and the figures that are to make up a plate should be
+arranged as stated above but not securely pasted until the grouping is
+satisfactory. In trimming each drawing or photograph the author should
+be careful to leave room at its lower edge for the number. Small
+drawings or photographs, such as paleontologists use, when pasted on
+bristol board or other board faced with tough paper are difficult or
+impossible to remove without injury if they have to be remounted;
+figures pasted on ordinary white or gray cardboard can be removed
+without difficulty. Each plate should be made up in a size to fit the
+volume or in its correct proportion to a page in the volume in which
+it is to be used (see table on p. 11), and each figure should be
+properly oriented--that is, all vertical lines, or the vertical axis
+of each specimen, should be parallel with the sides of the plate. When
+the figures are being mounted care should be taken that the mucilage
+or paste does not exude under pressure and cover any part of the
+drawing or photograph. The same attention should be given to pasting
+on numbers. Inattention to these details may produce results that
+will affect the reproduction of the plates.
+
+Ordinary mucilage may be used for mounting drawings and photographs,
+but photo paste gives good results and is perhaps cleaner to handle.
+Dry-mounting tissue is well adapted to mounting single illustrations
+but not groups of figures. Liquid rubber is sometimes used, but it is
+not suitable for mounting small figures, such as drawings and
+photographs of fossils. It can be used satisfactorily for mounting
+temporary plates and for mounting photographs in albums and on large
+cards for study or exhibition; but it has not proved to be a permanent
+adhesive. Its special merit is that it does not cause either the
+photograph or the mounting sheet to warp. It is applied by spreading
+it evenly over the back of the photograph with the fingers. The
+superfluous rubber can easily be removed from the hands and from the
+cards or sheets when it is dry. Anything mounted with liquid rubber
+can be easily removed.
+
+If a plate is to be made up of a small number of figures that require
+different reductions, the author, instead of mounting or pasting the
+separate figures on one card in the manner already indicated, may draw
+a rectangle of the size of the printed plate and sketch within it the
+several figures in their respective sizes and positions. These "dummy"
+plates or layouts should be numbered as plates, and they may bear
+captions and titles. The photographs or drawings represented by the
+sketches should then be numbered to identify them with the sketches on
+the dummy plate, and those that pertain to each plate should be
+inclosed in an envelope attached to the dummy plate. A plate made up
+in this manner will meet every requirement of the photo-engraver or
+lithographer.
+
+If a paleontologist so desires, his plates can be permanently made up
+after he has transmitted his material, but he should always submit a
+tentative arrangement.
+
+
+
+
+REUSE OF ILLUSTRATIONS.
+
+
+If an author desires to use in modified form an illustration already
+published, whether by the Geological Survey or by an outside
+publisher, he should furnish a print or tracing of the illustration
+showing the changes desired. If the illustration is not to be modified
+he need only give the title of the volume in which it was used, with
+the number of the page, figure, or plate, and he need not make a
+sketch of the illustration or furnish a dummy; but its title should be
+quoted and proper reference should be given in the list of
+illustrations. Due credit should be given to the author or publisher.
+
+The original cuts of illustrations will be kept for one year after the
+report for which they were made has been published, and authors of
+later reports may and should reuse, whenever practicable, any such
+cut that will serve as an illustration. In the author's list of
+illustrations such a cut should be referred to by its number as plate
+or figure and the volume in which it was first used.
+
+An electrotype of any cut on hand will be furnished for use in
+publications other than those of the Geological Survey at the cost of
+making, which is 3-1/2 to 5-1/2 cents a square inch of printing
+surface. The minimum charge for a single electrotype ranges from 46 to
+60 cents.
+
+
+
+
+APPROVAL OF FINISHED ILLUSTRATIONS.
+
+
+After the drawings for a report have been prepared they will be
+submitted to the author or to the chief of his branch or division for
+examination. The finished drawings will be accompanied by the
+"originals," with which the author should carefully and thoroughly
+compare them. After making a thorough comparison he should mark
+lightly with a pencil, on the finished drawings, all necessary
+corrections, or indicate his approval subject to such corrections and
+additions as may be required. He should verify all type matter and
+other lettering and assure himself that no mistakes have been made in
+grouping the photographs into plates, especially such as have been
+regrouped since they left his hands. The author's list of
+illustrations will be submitted with the new drawings for this
+purpose.
+
+
+
+
+REVISION OF ILLUSTRATIONS.
+
+
+All illustrations receive editorial revision before they are sent to
+the engravers. After they are drawn they are examined with reference
+to their scientific features and their accuracy, and then in turn with
+reference to the correctness of geologic names and geographic names
+and to errors in statement and in spelling. Each illustration thus,
+before it is completed, receives critical examination by persons
+qualified in particular kinds of work to detect errors or omissions.
+
+
+
+
+SUBMITTAL OF PROOFS.
+
+
+The first proofs of all illustrations are submitted to an author when
+he is within reach, but if he is in the field and the transmittal of
+the proofs to him is likely to cause too much delay they are submitted
+to the chief of the branch or division in which the report was
+prepared. Second proofs of the more complicated illustrations,
+particularly geologic maps, may be submitted. An author's examination
+should be confined principally to the revision of the scientific
+features of his illustrations, but suggestions as to general
+effectiveness are always acceptable.
+
+The process to be used in engraving each illustration is stamped in
+its lower left corner. In examining proofs an author should note the
+following facts:
+
+1. Changes can not be made in zinc etchings except by eliminating
+parts, cutting away defects, and connecting lines. If additions are
+required reengraving is generally necessary, and reengraving should
+preferably be avoided.
+
+2. Changes can be made in half-tone plates only by re-etching certain
+parts to make them lighter and by burnishing certain parts to make
+them darker. If the proof shows a general loss of detail the fault may
+lie either in the proving of the cut or in the reproduction. If it is
+in the reproduction it can not be remedied without reengraving. A
+slight loss of detail may be expected in all half tones, especially in
+those that are smaller than the copy submitted.
+
+3. Minor changes can be made in photolithographs and
+chromolithographs, but changes can not be made twice in one place
+without danger of affecting the printing. It is customary to approve
+all lithographic proofs subject to the corrections indicated, the
+printed edition being examined and compared, but if the changes are
+numerous and radical second proofs may be required. Second combined
+proofs of chromolithographs are very expensive. (See p. 89.)
+
+
+
+
+PROOF READING ILLUSTRATIONS.
+
+
+An author should examine the proofs of his illustrations closely and
+should compare them carefully with the original drawings. A mere
+cursory examination may fail to detect errors that have not been
+caught by the regular proof reader. Every correction desired should be
+clearly indicated with pen and ink in the body of the proof and
+inclosed in a loop from which a line should be carried to a marginal
+note or comment, but if the time available is short a pencil may be
+used. In correcting type matter or lettering (such as that in a
+geologic legend or explanation) the ordinary proof reader's marks
+should be used. The author or the person examining the proofs should
+initial each one at the place indicated by a rubber stamp.
+
+Proofs should be held only long enough to examine them properly and to
+compare them with the original illustrations, for a time limit is
+fixed in each contract for engraving, and if the author holds proofs
+beyond a reasonable time he causes a delay in the fulfillment of the
+contract.
+
+As the illustrations for many reports contain important data that will
+be discussed in the text, proofs of illustrations can not be supplied
+to any applicant without consent from the Director's office.
+
+
+
+
+GENERAL CONSIDERATIONS.
+
+
+The following requirements are essential to obtain good original
+illustrations:
+
+1. The material selected should be pertinent and expressive; it
+should have the qualities essential to good illustrations.
+
+2. The character of the report and the size of the illustrations
+should be kept clearly in mind. If the report is preliminary or
+ephemeral the illustrations should be simple and inexpensive. If the
+report represents the sum of knowledge on the subject treated or the
+last word on some particular area the illustrations may be more
+elaborate. The character of a report generally determines the form of
+publication, which, in turn, determines the size of the pages and the
+size of the plates and figures. Every sketch made should be larger
+than publication size--preferably twice publication size--whether it
+is a simple diagram or a base map.
+
+3. The kind of reproduction that is apparently needed should be fully
+considered, for it should have some relation to the kind of report.
+The illustrations for short-lived reports are reproduced by the
+cheaper processes. Those for hurried reports are reproduced by
+processes that can be worked quickly, but no process should be
+considered that will not give a clear reproduction of essential
+details.
+
+4. Clearness of preparation of original matter is invariably
+essential. An author should not expect the draftsmen or the editors to
+supply missing links. Each original should be complete and should be
+so made that it can be understood and followed without question.
+Changes made in the finished drawings or on proof sheets are expensive
+and delay publication.
+
+
+PART II. PREPARATION BY DRAFTSMEN.
+
+
+
+
+GENERAL DIRECTIONS.
+
+
+The work of preparing illustrations such as are used in the reports of
+the Geological Survey is essentially that of making finished drawings
+from more or less crude and imperfect material furnished by authors to
+illustrate certain features or phenomena discussed in their
+manuscripts. Each finished drawing must be so prepared that it can be
+reproduced in multiple by one of several processes of engraving. The
+author's sketches and other material are commonly called "originals";
+the finished illustrations are known by the engravers as "copy."
+Though most engraver's copy consists of more or less elaborate
+drawings that are to be reproduced in facsimile by "direct" processes
+without the interposition of handwork, some of it consists of more
+roughly prepared copy which is accurate in statement but requires
+complete manual or "indirect" reproduction. The direct processes in
+use are zinc etching, half-tone engraving, photolithography,
+three-color half tone, photogravure, and photogelatin. The manual or
+indirect processes are wax engraving, wood engraving, engraving on
+copper and on stone, plain lithography, and chromolithography. These
+processes are described on pages 72-90.
+
+Part I of this pamphlet contains some matter that is pertinent to
+final preparation and should be consulted by draftsmen.
+
+To prepare a drawing that will be in every way suitable for
+reproduction usually requires experience of a kind not acquired in
+many other kinds of drafting, such as preparing engineers' or
+architects' drawings, because the drawings themselves or blue prints
+made directly from them are the things the engineer or the architect
+desires. Drawings prepared for reproduction are generally made larger
+than publication size, and it is therefore necessary to gage each
+line, letter, or feature for a definite reduction. Engineers' and
+architects' drawings generally do not require preparation for
+reproduction by any process, but in preparing illustrations for the
+reports of the Geological Survey reproduction must be fully considered
+at every step, and each drawing must be made according to the
+requirements of a certain selected process and gaged for a certain
+reduction. The draftsman should therefore know how to plan each
+drawing step by step for an engraved cut, a lithograph, a text figure,
+or a plate, always with a definite result in view. He should be
+familiar with processes of engraving and should know the special
+requirements of each process, and he should be able to prepare
+drawings for any specified reduction in a way to insure good, legible
+reproduction.
+
+The geologic draftsman should read and study such textbooks of geology
+as those of Dana and Geikie and should familiarize himself with
+structural geology, the geologic time divisions, and geologic
+nomenclature. He should be able to prepare a simple, effective
+illustration from complicated rough originals and to supply minor
+missing essential parts or features. To perform his work successfully
+he must possess mechanical skill and some artistic taste, as well as
+good eyesight and great patience.
+
+
+
+
+INSTRUMENTS.
+
+
+The following list of draftsmen's instruments is practically complete.
+Those which are considered indispensable are marked by asterisks; the
+others may be used according to individual preference. The same kind
+of instrument may be duplicated in different sizes according to the
+variation in the demands of the work.
+
+ Air brush and connections. Pens, Payzant's, 1 set.
+ Beam compass. *Pencils, best quality, graded
+ Bow pen, drop spring. leads.
+ *Bow pen, steel spring. *Protractor.
+ Bow pencil, steel spring. Railroad curves, pearwood, 1 set.
+ *Brushes, red sable. Railroad pen.
+ China saucers. *Railroad pencil.
+ *Color box. Reading glass.
+ *Compass, pen and pencil points. *Reducing glass.
+ Crayons, assorted colors. *Ruling pen.
+ Curve rule, adjustable. Scale, boxwood, 12 inches long,
+ *Dividers, plain. with divisions of millimeters
+ *Dividers, proportional. and inches.
+ Dividers, steel spring. Scales, boxwood, triangular.
+ Drawing boards, several sizes. Section liner (parallel ruling
+ Eraser, glass. device).
+ *Eraser, rubber, hard. Straightedge, steel, 24 inches.
+ *Eraser, rubber, soft. Straightedge, steel, 36 inches,
+ *Eraser, steel. with divisions for hundredths
+ Erasing shield. of an inch and millimeters.
+ *French curves, xylonite. *Straightedge, wood, 24 inches.
+ Microscope, low power and Swivel or curve pen.
+ lenses. Thumb tacks.
+ Palette knife. Tracing point, steel.
+ Pantograph. *Triangle, 45°.
+ Pens, double-pointed. *Triangle, 60°.
+ *Pens, Gillott's, Nos. 170, *T square, pearwood, xylonite edge.
+ 290, 291. *Tweezers, dentist's.
+ Pens, K. & E., drawing. No. 3202.
+
+
+
+CLASSIFICATION OF MATERIAL.
+
+
+The draftsman handling the drawings and other original material
+submitted by the author of a report for its illustration should first
+group them, as far as possible, into kinds or classes, in order that
+he may decide how each illustration should be prepared (1) to express
+most effectively the author's purpose, (2) to insure reasonable
+economy in preparation and in reproduction, and (3) to meet the
+requirements of the processes of reproduction selected. All similar
+illustrations for one publication should be prepared in the same
+general style. In a series of geologic sections, for example, the same
+lithologic symbols should be used throughout for the same kinds of
+rocks. The titles, explanations, and captions of the maps should also
+agree with one another in general style and in details of workmanship.
+
+The draftsman should determine in advance the reduction for each
+drawing or for each group of drawings, in order that he may use the
+same size of letters or the same kinds of type for the lettering on a
+series of drawings that require the same reduction. The reduction
+should preferably be marked in fractions (as "1/2 off," "1/4 off" or
+"reduce 1/2," "reduce 1/4"), and the choice of the same reduction for
+a group of drawings will not only insure greater uniformity in the
+drafting and in the reproduction but will permit the drawings to be
+reproduced more economically, for the engraver can photograph them in
+groups instead of each one separately.
+
+The draftsman should therefore note and consider (1) the special
+features shown in the author's originals; (2) whether or not these
+features have been plainly indicated and whether the originals are
+complete; (3) the size of the printed page of the volume in which the
+illustrations will appear and the reduction required for each drawing;
+and (4) the process by which each drawing should be reproduced. If an
+original is of doubtful or uncertain interpretation or appears to be
+incomplete the draftsman should confer with the author of the paper if
+he is within reach or should bring the matter to the attention of the
+chief of the branch; otherwise he may waste much time in making the
+drawing.
+
+
+
+
+PREPARATION OF MAPS.
+
+
+PROJECTION.
+
+The base maps furnished by authors (see pp. 13-14) are prepared in
+many different ways and in different degrees of refinement and of
+crudity, but the work of redrawing them for reproduction involves
+well-established and generally uniform principles. All maps except
+those of very extensive areas should be based on a map projection
+which will show with a minimum of distortion the effect of the
+curvature of the earth. The polyconic projection (see fig. 5) is used
+for most Government maps. In this projection the central meridian is
+a straight vertical line, and each parallel of latitude is developed
+independently of the others. The mathematical elements of map
+projection are given in tables published by the Geological Survey[6]
+and the Coast and Geodetic Survey.[7] Figure 5, however, illustrates
+the mechanical or constructional features of the polyconic projection
+and if used in connection with the published tables will probably be
+a sufficient guide for projecting a map on any desired scale.
+
+[Footnote 6: Gannett, S. S., Geographic tables and formulas, 4th ed.:
+U. S. Geol. Survey Bull. 650, 1916. See also Gannett, Henry, Manual of
+topographic methods: U. S. Geol. Survey Bull. 307, pp. 85-86, 1906.]
+
+[Footnote 7: Methods and results: Tables for the projection of maps
+and polyconic development; Appendix No. 6, Report for 1884; Tables for
+a polyconic projection of maps, based upon Clarke's reference spheroid
+of 1886; 3d ed., 1910.]
+
+[Illustration: Figure 5.--Diagram illustrating method of projecting a
+map.]
+
+In projecting a map first select a convenient measuring scale for
+setting off the dimensions given in the tables, or if no scale is at
+hand one may be constructed. Measuring scales are made, however,
+bearing divisions for miles and kilometers and finer subdivisions of 6
+to 100 parts. They include the ratios of 1:31,250, 1:31,680, 1:48,000,
+1:62,500, 1:63,360, 1:125,000, 1:250,000, 1:500,000, 1:1,000,000, and
+others. On a map drawn on the scale of 1 to 63,360, for example, 1
+inch would represent 1 mile; on a map drawn on the scale of 1 to
+1,000,000, 1 millimeter would represent 1 kilometer, and so on. It
+will be seen that the use of a scale that shows in ratios, such as
+those just given, the actual distance on the ground as compared with
+the unit representing the same distance on the map will reduce the
+possibility of error.
+
+The method of projecting a map, illustrated in the accompanying
+diagram (fig. 5), is as follows: First draw a straight vertical line
+(A) through the middle of the sheet to represent the central meridian
+of the map and a line (B) at the lower end of this line exactly at
+right angles to it to represent the bottom of the map. Then set off on
+the line showing the central meridian the distances between parallels
+given in Table 6 on page 36 of "Geographic tables and formulas" (Bull.
+650). It should be noted that the figures in these tables give the
+distance, in meters and statute miles, of 1° on a meridian measured
+30' each way from a point where the meridian is intersected by a
+parallel. The exact distances between parallels as measured on the
+ground are given in the Coast and Geodetic Survey tables, or they may
+be computed from Table 6 of "Geographic tables and formulas" by adding
+the sum of the figures given for any two latitudes 1° apart and
+dividing by 2.
+
+The distance between parallels that are 2° apart, as shown in the
+diagram, may be computed from Table 6 of "Geographic tables and
+formulas," as follows:
+
+ Meters. Meters.
+
+1° of latitude on 37th parallel = 100,975.1 / 2 = 55,487.5
+1° of latitude on 36th parallel = 110,956.2
+1° of latitude on 35th parallel = 110,937.6 / 2 = 55,468.8
+ ---------
+True distance from 35° to 37° latitude = 221,912.5
+
+The distances given in the diagram were obtained by adding the figures
+given in the Coast and Geodetic Survey tables, which yield the same
+results. Other tables in Bulletin 650 give the true distances in
+inches on maps of certain standard scales.
+
+Through the points thus obtained on the central meridian draw lines at
+right angles to the vertical line. Along these horizontal lines lay
+off the dimensions in the column headed X, Table 6 (pp. 39-47) of
+"Geographic tables and formulas" as required for each individual
+map--in the diagram every alternate degree. Draw vertical lines at
+these points and set off the distance Y in the same table in a similar
+manner, and the points so found will be the points of intersection of
+the respective meridians and parallels. Figures are given on the
+diagram for the thirty-fifth parallel only.
+
+
+DETAILS OF BASE MAPS.
+
+Anyone who attempts to draw a base map must, first of all, know how
+each feature or part of the map should be represented. Most of the
+conventional symbols for features shown on base maps are well
+established and should invariably be used; for instance, a line
+composed of alternate long and short dashes (not dashes and dots)
+represents a county boundary, and a line or two parallel lines across
+which short lines are drawn at regular intervals represents a
+railroad. If he finds that two or more symbols have been widely used
+to represent the same feature the draftsman should select the one that
+is best suited to the map in hand. The correct forms of the
+conventional symbols or features to be used in preparing miscellaneous
+maps are shown in Plate IV, but the size and weight of each line or
+symbol must depend on the size and character of the map.
+
+
+TRANSFERRING OF COPYING.
+
+TRACING.
+
+The oldest method of transferring a map or parts of a map or other
+drawing to another sheet is that of copying it by means of tracing
+paper. This method, though still used for simple work, has given way
+to quicker and more effective methods. By one of these methods a piece
+of thin, fairly smooth paper (not necessarily transparent) is coated
+with graphite by rubbing over it a soft pencil. When the graphite has
+been evenly distributed over it, this sheet is laid upon the drawing
+paper, coated side down, the map or other subject to be copied is laid
+upon the graphite-coated sheet, and the two outer sheets--the drawing
+paper and the map--are securely fastened together. By a steel tracing
+point or very hard pencil the lines and other details of the matter to
+be copied are then firmly and carefully traced and thus transferred to
+the clean drawing paper beneath.
+
+For maps that show several features in different colors sheets rubbed
+with blue, orange, brown, or green pencils may be used, one after
+another, for tracing each set of the features. Red should not be used,
+as it is not easily erased. This method insures distinctive lines for
+the separate features and prevents the confusion that might result
+from the use of one color only. Exact register of the features shown
+in the several colors used may be insured by fastening one edge of the
+drawing to be copied to the drawing paper by mucilage or thumb tacks.
+The colored sheets may then be slipped in and out without altering the
+position of the lines or symbols for one set of data with relation to
+those for the others.
+
+In the final preparation of a base map to be engraved and printed in
+colors--for example, black, blue, and brown--tracings of the three
+colors appearing on the original base should generally be transferred,
+as described above, to one sheet of paper and thus worked up into a
+three-colored map. It is usually unnecessary and undesirable to draw
+each color on a separate sheet. The preparation of separate drawings
+may facilitate reproduction, but if they are made on tracing cloth the
+usual uneven shrinking or stretching of the cloth may produce
+misregister in the printing; therefore it is safer to make a single
+drawing, so that the photolithographer can make three negatives and
+separate the colors by painting out or "opaquing" the colors not
+wanted on each negative. A map drawn on a single sheet is also less
+bulky and can therefore be more conveniently handled and compared with
+proof.
+
+If for any reason separate tracings for the different colors to be
+used on a map are considered desirable they should be made on linen
+cut from one roll and in the same direction according to the warp and
+woof.
+
+CELLULOID TRANSFERRING.
+
+In the celluloid method of transferring a map or parts of a map to
+paper upon which a complete new map is to be drawn the map or part of
+the map to be copied is photographed to the exact scale of the new
+drawing and reproduced in graphite on thin sheets of celluloid.
+
+The celluloid sheet is then laid face down in the correct position on
+the drawing paper and firmly rubbed on the back with a steel
+burnisher, which makes a perfect offset of the map on the paper. After
+the parts desired are inked over the rest of the graphite print is
+easily erased with an ordinary rubber.
+
+By using this method it is possible to get absolute scale and more
+satisfactory results than by tracing over a photographic print line
+for line or by using a pantograph.
+
+Requisitions for celluloid prints are made on the form used for
+requesting photolithographic work.
+
+SKETCHING BY RETICULATION.
+
+If the sheet bearing the design or matter to be copied may be marred
+without objection it is ruled lightly into pencil squares of equal
+size. Corresponding squares of the same size, larger, or smaller,
+according to the size of the new drawing, are then ruled on the
+drawing paper, and the work is sketched square by square. If the
+original sheet may not be marred the same result can be obtained by
+drawing the lines on a transparent oversheet. This method is
+serviceable for enlarging or reducing simple work that includes no
+great amount of detail; if great precision of detail is required the
+original should be enlarged or reduced by photography or by the
+pantograph.
+
+THE "SHADOWLESS DRAFTING TABLE."
+
+One of the most useful contrivances that has been made for tracing a
+drawing on the same scale is called by its manufacturers the
+"shadowless drafting table." The essential features of this table are
+a wooden box inclosing strong incandescent lights and bearing a
+ground-glass top. A drawing placed on the ground glass can be so
+illuminated as to make its lines conspicuous and readily traceable
+even through relatively thick paper. The table is particularly useful
+for tracing sheets upon, which the lines are indistinct and would not
+be discernible under tracing paper with reflected light. It is also
+useful in preparing drawings in which certain features must register
+perfectly over each other. In fact any drawing that does not require
+enlarging or reducing can be traced with great facility by the use of
+this drafting table, and it is particularly useful for tracing faint
+lines on old and poorly preserved prints or drawings.
+
+Such a table has been installed in the section of illustrations, where
+it can be used by authors and others.
+
+
+TOPOGRAPHIC FEATURES.
+
+RELIEF.
+
+The effect of relief is expressed on a map by three methods--by
+contours, by hachures, and by shading. (See fig. 6.) The first method
+does not give pronounced pictorial expression of relief, though it
+gives correct shape and exact elevation; the others are mow pictorial,
+but they do not give exact elevation.
+
+_Contours._--As contoured maps are originally prepared from actual
+surveys the draftsman should simply follow the copy furnished by the
+topographer or such original matter as may be given to him for
+redrawing. If the area mapped is large and the contours are close
+together the original may be transferred by celluloid tracing (see p.
+47), or it may be transferred by tracing with graphite-coated paper
+(see p. 46). After the contour lines have been transferred they should
+be traced in ink, in lines of even thickness, except those that
+represent certain fixed intervals and are to be numbered, which should
+be made slightly thicker. (See fig. 6, A.) In drawing these lines some
+draftsmen use an ordinary ruling pen, others the swivel pen; but
+considerable practice is required in the use of either before it can
+be controlled to follow precisely the penciled lines. Still other
+draftsmen use the Shepard pen or an ordinary drawing pen. The swivel
+pen, if expertly handled, produces a firm and even line.
+
+Italic numbers should be used to indicate the elevation of a contour
+and should be placed in an opening in the line, never between lines.
+Where the lines run close together great care should be taken that
+they do not touch unless the interspaces are so narrow that they must
+touch and combine. The lines should be firm and even, and if the copy
+or original map shows that they are uniformly very close together it
+should be enlarged before the tracing is made in order to give more
+freedom in drawing; but if the enlarged map is to be much reduced care
+should be taken to make the lines proportionate to the reduction. A
+photo-engraving of a map on which the contour lines are drawn very
+close together is likely to be unsatisfactory because, though the
+spaces between the lines are reduced in width, the lines themselves
+may show no corresponding reduction in thickness.
+
+[Illustration: Figure 6.--Methods of expressing relief: (A) by contour
+lines, (B) by hachures, (C) by shading on stipple board, and (D) by a
+brush drawing. The four examples given represent the same area. The
+drawings were made twice the size of the printed cuts.]
+
+Certain contour lines are commonly accentuated on a map, generally
+every fourth or fifth line--that is, for a 10-foot interval every
+50-foot line, for a 20-foot interval every 100-foot line, for a
+25-foot interval every 100-foot line, for a 50-foot interval every
+250-foot line, and for a 100-foot interval every 500-foot line.
+
+_Hachuring._--The effect of relief can be produced satisfactorily by
+hachuring but only by a draftsman who has had considerable
+well-directed practice in that kind of drawing. In a hachured map the
+light should seem to come from the west or northwest--that is, the
+darker parts should be on the east or southeast side of an elevation
+and the lighter parts on the west or northwest The highest elevation
+should be represented by the darkest shade on the right and by a
+corresponding high light on the left. The hachuring should begin at
+the crest of a peak, range, or butte and be worked downward toward the
+gentler slopes, the lines being drawn farther apart and made thinner
+until the floor of the valley is reached and the effect of shadow is
+lost by fewer and lighter lines. On a hachured map that is made from a
+contoured map somewhat definite differences of elevation may be
+indicated by the intervals between the strokes, and abrupt changes in
+slope may be indicated by shorter and heavier lines. The strokes
+should be disjointed, and they should trend at right angles to the
+upper margin of a cliff and should radiate from a peak. Figure 6, B,
+represents satisfactory hachuring.
+
+_Hill shading._--Relief is more easily expressed by shading than by
+hachuring. (See fig. 6, C, D.) The draftsman can best express it by
+this means after he has studied contoured maps or photographs of the
+region mapped, if they are available, in order that he may obtain an
+idea of the details of its topography.
+
+The special means used to produce hill shading will depend on the
+character of surface of the paper on which the drawing is to be made,
+the size of the map, the amount of detail and refinement of execution
+desired, and the amount of reduction to be made in reproducing the
+drawing. For maps on which it is desired to show some refinement of
+drawing and detail, a lithographic or wax crayon can be used on paper
+which has a grained surface. The draftsman must express relief
+according to the information he has at hand, whether detailed or
+general, and must employ methods that accord with the purpose of the
+map and the mode of reproduction selected. If a shaded relief map is
+to be prepared for direct reproduction by photolithography and the
+shading is to be printed in a separate color the base map should be
+completed first and a light photographic or blue print obtained on
+which to add the relief in black lithographic crayon, to insure
+perfect fitting of the relief and the base; or the relief can be
+prepared on an oversheet--a semitransparent white paper with
+sufficient "tooth" or grain to cut the shading up into minute dots.
+The shadowless drafting table (see p. 47) is especially useful for
+this purpose. On this oversheet register marks should be placed at the
+four comers and at several other points, particularly at the
+intersection of parallels and meridians.
+
+For relief shading on small black and white maps Ross's hand-stipple
+drawing paper may be used. (See p. 24.) By rubbing a black wax crayon
+or pencil over the surface of the paper the desired effect is produced
+in fine dots or in stipple, which may be varied in density of shade at
+the will of the draftsman. (See fig. 6, C.) High lights can be
+produced by scraping away the chalky surface of the paper. A
+lithographic or wax crayon is the best medium to use on this stipple
+paper, as on the paper referred to in the preceding paragraph, for the
+shading produced by it is not so easily smeared as that produced in
+pastel or by a graphite pencil. The object of using either the rough
+paper or Boss's stipple paper for drawings that are to be reproduced
+by photo-engraving is to produce a shading that is broken up into dots
+of varying sizes, which is essential in such reproduction.
+
+Belief shading for maps can also be made with a brush in flat washes
+of either india ink or lampblack. Such shading should be made only
+over a blue print or an impression of some kind from the map upon
+which the shading or relief is to be overprinted. If the relief is
+expressed on the author's original by contours the general shapes of
+the relief and the drainage lines can be traced and transferred
+lightly in blue lines to form a base on which to model the shading and
+at the same time to make the shading fit the streams. Such a drawing
+can be photographed through a screen and reproduced by half tone (see
+fig. 6, D) or mezzotint as a separate plate made to overprint the map
+in another color.
+
+HYDROGRAPHY.
+
+_General directions._--The drainage features of a map should be so
+drawn as to suggest the natural courses of the streams. Streams should
+not be drawn in straight, hard lines, as such lines are decidedly
+unnatural and produce a crude effect. The course of a river may be
+straight in general, but it is likely to be somewhat sinuous in
+detail. If the streams shown on a preliminary map are drawn in a
+clumsy or characterless fashion they should be redrawn with a freehand
+effect or made slightly wavy, in order that they may appear more
+natural. The gradual widening of streams from source to mouth should
+also be shown in the drawing. On small-scale maps, where the eye can
+at once see a stream through its full length, this almost
+imperceptible widening can be expressed by a line of almost uniform
+weight except for the stretch near the source, where it should grow
+thinner and taper off. On maps which are to be reproduced directly
+from drawings in black and white and which are to show both contour
+lines and drainage the lines representing the streams and other water
+bodies should generally be drawn freehand and slightly heavier than
+the contour lines, which should be sharper and more precise.
+
+The names of all streams or other bodies of water should be in italic
+letters, those of the larger streams being lettered in capitals and
+those of the smaller streams in capitals and lower-case letters. (See
+"Lettering," p. 53.)
+
+_Water lining._--The use of water lining on black and white maps
+should be limited to maps on which the water areas are not readily
+distinguishable from the land areas. In rough drawings that are to
+serve only as copy for engravers a flat color may be used for water
+areas and its conversion into water lines specified. In base maps to
+be reproduced in three colors a light-blue tint may be used in lieu of
+water lining, and it can be printed either flat or in a fine ruling
+transferred to the stone that is to print the drainage. The engraving
+of water lines is expensive, and the flat blue color should generally
+be preferred.
+
+Water lining usually consists of 30 to 45 lines on engraved or large
+maps, but on small maps and sketch maps the number may be reduced as
+desired. Care should be taken that the lines are as nearly parallel as
+they can be made freehand and of even weight or thickness. The first
+three to six lines outside the coast line should be somewhat closer
+together than those farther out and should conform closely to the
+coast line, but the spacing between the lines should increase and the
+lines should become almost imperceptibly less conformable to the coast
+line as they reach their outer limit, the last three to six being made
+with the greatest care and refinement. Water-lined maps that are to be
+reproduced by photographic processes should be drawn at least twice
+publication size. The reduction will bring the lines closer together,
+and the reproduction will show a more refined effect than could
+possibly be produced by the most skillful drawing.
+
+Good examples of water lining, such as are shown on the topographic
+atlas sheets of the Survey, should be studied by draftsmen before
+they undertake such work.
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE IV
+
+
+SYMBOLS USED ON BASE MAPS]
+
+
+CULTURAL FEATURES.
+
+The cultural features represented on a map include "the works of
+man"--not only cities, towns, buildings, bridges, railroads, and other
+roads, but State, county, and other boundary lines--in short, all that
+part of a three-color base map which is shown in black, the engraved
+plate for the black being called the culture plate. The features named
+in the list below are the cultural features referred to. (See PL IV
+for corresponding symbols.)
+
+Aqueduct mains.
+Aqueduct tunnels.
+Bench marks.
+Boundary Lines.
+Boundary monuments.
+Breakwaters.
+Bridges.
+Buildings.
+Cable Lines.
+Camps.
+Canal locks.
+Canals.
+Cemeteries.
+Churches.
+Cities.
+County lines.
+Dams.
+District lines.
+Ditches.
+Electric power lines.
+Fences.
+Ferries.
+Fords.
+Gas wells.
+Hedges.
+
+Hospitals.
+Jetties.
+Land-grant lines.
+Land-section Lines.
+Levees.
+Mains.
+Mineral monuments.
+Mine tunnels.
+Mines.
+National forests.
+National parks.
+Oil tanks.
+Oil wells.
+Open cuts.
+Park boundaries.
+Paths.
+Pits.
+Post offices.
+Precinct lines.
+Prospects.
+Province lines.
+Quarries.
+Quarter-section lines.
+Railroads, steam or electric.
+
+Ranches.
+Reservation boundaries.
+Reservoirs.
+Roads.
+Ruins.
+Schoolhouses.
+Section comers.
+Section Lines.
+Settlements.
+Shafts.
+Streets.
+Telegraph Lines.
+Towns.
+Township comers.
+Townships.
+Trails.
+Tramways.
+Triangulation stations.
+Tunnels.
+Villages.
+Water mains.
+Water wells.
+Waterworks.
+Windmills.
+
+
+LETTERING.
+
+GENERAL DIRECTIONS.
+
+The cultural features are named on maps by letters of two distinct
+styles--slanting gothic for public works and roman for habitations and
+civil divisions. The size of the letters used should indicate in a
+general way the relative importance of the feature or group to which
+they are applied, but on some maps the county seats, State capitals,
+and large cities may be distinguished by different symbols. The names
+of civil divisions are lettered in sizes depending on their relative
+grade and the size of the area or space in which the names are to
+appear.
+
+The features shown on a topographic map may be broadly separated into
+four groups and are lettered as follows:
+
+Civil divisions (countries, States, counties, townships, land grants,
+reservations, cities, towns, villages, settlements, schools, lodges,
+ranches, etc.), roman capitals or capitals and lower case.
+
+Public works (railroads, tunnels, roads, canals, ferries, bridges,
+fords, dams, mains, mines, forts, trails, etc.), slanting gothic
+capitals (light) or capitals and lower case.
+
+Hydrographic features (oceans, seas, gulfs, bays, lakes, ponds,
+rivers, creeks, brooks, springs, wells, falls, rapids, marshes,
+glaciers, etc.), italic capitals or capitals and lower case.
+
+Hypsographic features (mountains, ranges, peaks, plateaus, cliffs,
+buttes, canyons, valleys, peninsulas, islands, capes, etc.), upright
+gothic capitals (light) or capitals and lower case.
+
+The essential principles of lettering have been described in numerous
+treatises and are well understood by most draftsmen. The correct form
+of each letter may be learned from such treatises, but spacing and
+arrangement are best learned by observation and experience. Good
+lettering will not strongly attract attention, but even slight
+imperfections of form, spacing, slant, and shading will be quickly
+detected and criticized. Map letterers should note that the name of a
+place or the number of a symbol should be put to the right of the
+symbol if possible and a little above or below it--not to the left and
+directly on a line with it, as Tucson=o=, 17=o=, Dallas=o=, Carson=o=.
+Names indicating large areas, if written from west to east, should
+curve with the parallels, and all names should be so lettered that "if
+they should fall they would fall on their feet." Every name should be
+distinctly legible but not so conspicuous as to subordinate the
+feature it designates. Lines should therefore not be broken in order
+to make the lettering clear except where there is possible danger that
+the smaller spaces may be filled up in printing. The lettering on a
+map should always be so spaced that it will properly fit the area it
+is intended to designate. In names consisting of two or more words the
+letters should not be closely spaced if wide spaces are left between
+the words. In numbers, except those used to indicate elevations on
+contour Lines or elsewhere, thousands should always be set off by
+commas.
+
+Draftsmen often draw bad forms for commas, quotation marks,
+apostrophes, and question marks. The following forms are correct:
+Comma , ; quotation marks "" ; apostrophe ' ; question mark ? .
+
+LETTERING BY TYPE.
+
+Names and short notes printed from type on paper, to be cut out and
+pasted in proper positions on maps or other drawings, now furnish a
+large proportion of the lettering on the Survey's illustrations. The
+strips are likely to become detached by the repeated handling of a
+drawing, however, unless they are securely pasted on. The best results
+can be obtained by having the type printed on a special brand of
+"noncurling" gummed paper, from which the lettering is cut in squares
+or strips, which are dampened and applied to the proper places on the
+drawing. In handling such strips a pair of dentist's tweezers is
+useful. When mucilage is applied to printed strips of ordinary paper
+the moisture causes the paper to warp or curl, often so much as to
+affect the reproduction of the drawing. This printed lettering is
+generally used, however, only for headings, titles, notes, and other
+matter that stands alone; it should not be used for the geographic
+names in the body of a map unless only a few names are to appear, for
+the strips of paper bearing the names may obscure parts of the map.
+The reproduction of this lettering by photo-engraving or
+photolithography gives results superior to those obtained from hand
+lettering unless each letter is made with the utmost care, work which
+is considered a waste of time.
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE V
+
+
+REDUCTION SHEET USED IN LETTERING ILLUSTRATIONS.
+
+The largest size shows the letters unreduced; the other sizes show
+the letters reduced as indicated in the margin.]
+
+Type is used also for printing lettering directly on a drawing exactly
+in proper position, by a special type holder, somewhat like a
+self-inking stamp.
+
+Most of the styles and sizes of type now used on maps in the Survey's
+reports are shown in Plate V.
+
+If a drawing is to be reduced one-half the smallest type used should
+be about 2 millimeters in height; if it is to be reduced one-third the
+smallest type used should be about 1.5 millimeters in height; and so
+on. No letter whose vertical height after reproduction would be less
+than about 1 millimeter should be used, and the larger lettering
+should bear a proper relation to the smaller. Sheets showing the
+styles of type in use by the Survey, in full size and reduced
+one-fourth, one-third, two-fifths, one-half, three-fifths, two-thirds,
+and three-fourths, will be furnished on request. If a drawing is to be
+reduced one-half, for example, the sheet that has been reduced
+one-half will show the size of the lettering on the printed plate, so
+that the draftsman, by referring to the sheet showing the reduction he
+desires, can select type of a size that will be legible. Plate V shows
+a part of this reduction sheet.
+
+ABBREVIATIONS.
+
+The following are the correct forms for abbreviations used on maps and
+other illustrations:
+
+A. Arroyo.
+B. M. Bench mark.
+Bdy. Boundary.
+Br. Branch, bridge.
+C. Cape.
+Can. Canal, canyon.
+Cem. Cemetery.
+Co. County.
+Cr. Creek.
+E. East.
+El. Elevation.
+Est. Estuary.
+Fk. Fork.
+Ft. Fort, foot.
+Gl. Gulch, glacier.
+Hrb. Harbor.
+I. Island.
+Is. Islands.
+Jc. Junction.
+L. Lake.
+Lat. Latitude.
+Ldg. Landing.
+L. S. S. Life-saving station.
+L. H. Lighthouse.
+Long. Longitude.
+M. P. Milepost.
+M. M. Mineral monument.
+Mt. Mount.
+Mtn. Mountain.
+Mts. Mountains.
+N. North.
+Pen. Peninsula.
+Pk. Peak.
+P. O. Post office.
+Pt. Point.
+R. Range, river.
+Res. Reservation, reservoir.
+R. H. Road house.
+S. South.
+Sd. Sound.
+S. H. Schoolhouse.
+Sta. Station.
+Str. Stream.
+T. Township.
+Tel. Telegraph.
+W. West.
+
+Words like mount, river, point should not be abbreviated where they
+form a part of the name of a city or town, as Rocky Mount, Fall River,
+West Point. Neither the word nor the abbreviation for railroad or
+railway should be placed on a map; the chartered name (or initials of
+the name) and the road symbol are sufficient.
+
+Names of States and Territories should be abbreviated, where
+abbreviation is necessary, as follows:
+
+Ala. Ga. Minn. N. J. Tenn.
+Ariz. Ill. Miss. N. Mex. Tex.
+Ark. Ind. Mo. N. Y. Va.
+Calif. Kans. Mont. Okla. Vt.
+Colo. Ky. Nebr. Oreg. Wash.
+Conn. La. Nev. Pa. W. Va
+D. C. Mass. N. C. R. I. Wis.
+Del. Md. N. Dak. S. C. Wyo.
+Fla. Mich. N. H. S. Dak.
+
+Alaska, Guam, Hawaii, Idaho, Iowa, Maine, Ohio, Samoa, and Utah should
+be written in full.
+
+The abbreviations used on the margins of maps for subdivisions of land
+should be as follows (note punctuation): T. 2 N., E. 3 W. On
+large-scale plats the marginal lettering should be as follows: N. 1/2
+NE. 1/4 sec. 1, T. 7 N., K 2 W.; fractional secs. 2 and 35, Tps. 7 and
+8 N., R. 2 W.; NW. 1/4 sec. 20, T, 7 N., R. 2 W. In spelling fractions
+use half and quarter, not one-half and one-quarter.
+
+The abbreviated forms of such names as North Fork and South Fork
+should be N. Fork and S. Fork, not North Fk. and South Fk.
+
+Additional abbreviations used on illustrations are as follows:
+
+ N. for north, NE. for northeast, NNE. for north-northeast, etc.
+ Capitalize directions affixed to street names, as NW., SE.
+ (1800 F St. NW.).
+
+ Sec. and secs. for section and sections before a number.
+ Capitalize only at the beginning of a line or sentence.
+
+ a. m. and p. m. for antemeridian and postmeridian, as 4.30 p. m.
+ Lower-case unless in line of caps.
+
+ & in names of corporations or companies. On Survey miscellaneous
+ maps "and" is spelled out in railroad names.
+
+ B. t. u. for British thermal units.
+
+ bbl., bbls. for barrel, barrels.
+
+ bu. for bushel or bushels.
+
+ c. c. for cubic centimeter.
+
+ cm. for centimeter.
+
+ cwt. for hundredweight.
+
+ dwt. or pwt. for pennyweight
+
+ oz. for ounce or ounces.
+
+ etc. (not &c.) for et cetera.
+
+ ft. for foot or feet.
+
+ H. m. s. for hours, minutes, and seconds. (Use capital H.)
+
+ in. for inch or inches.
+
+ kw. for kilowatt or kilowatts.
+
+ £ s. d. for pounds, shillings, and pence.
+
+ per cent (omitting period) for per centum. Spell out percentage.
+
+ ser. for series.
+
+ St. for Saint or street
+
+ U. S. Army for United States Army, as distinguished from United
+ States of America (U. S. A.).
+
+ yd., yds. for yard, yards.
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE VI
+
+
+ 175-LINE SCREEN 150-LINE SCREEN
+
+ 133-LINE SCREEN 120-LINE SCREEN
+
+ 100-LINE SCREEN 65-LINE SCREEN
+
+HALF-TONE CUTS SHOWING EFFECT OF SEVERAL STANDARD SCREENS IN THE
+REPRODUCTION OF THE SAME DETAIL.]
+
+The names of certain months may in some places be abbreviated; those
+of others should invariably be spelled out. The following are the
+correct forms:
+
+ Jan. Apr. July Oct.
+ Feb. May Aug. Nov.
+ Mar. June Sept Dec.
+
+The abbreviations for number and numbers before figures are No. and
+Nos. The o should never be raised, as in N^o. The abbreviation for Mac
+is Mc, not M^c.
+
+All periods should be omitted from abbreviations used in the body of a
+map unless their omission would cause misunderstanding. They are
+generally unnecessary, and if used on some maps they are likely to be
+mistaken for symbols representing certain features, such as houses or
+flowing wells, if either is shown. Periods used on drawings that are
+to be reproduced "direct" or photomechanically should always be
+slightly exaggerated.
+
+NAMES OF RAILROADS.
+
+The names of railroads may be written in full or abbreviated, in
+accordance with the kind of map and the space available. On a sketch
+map in black and white the initial letters are generally sufficient.
+On a more detailed map, if there is room enough, the names may be
+spelled out. As already stated, neither the words "railroad" and
+"railway" nor the abbreviations R. R. and Ry. should be used on a map.
+
+
+MAKE-UP OF MAPS.
+
+FORMS FOR CERTAIN FEATURES.
+
+The proper forms for certain features of maps, such as the borders,
+titles, explanations, bar scales, captions, arrows indicating true
+north and magnetic declination, source, and authorship, are shown in
+Plate VII. Note particularly the style and position of the marginal
+matter.
+
+BORDER.
+
+A finished map border is used or omitted according to the kind of map
+prepared. Diagrammatic maps and maps on which no parallels and
+meridians appear do not need finished borders. On a map that shows
+complete areal geologic or other coloring, such as a map in a Survey
+geologic folio, the border lines tend to destroy the simple effect of
+the whole map. On a map that is not completely colored and on all very
+large maps borders are really necessary. If borders are used, however,
+the space between the neat line and the outer line of the border
+should be only sufficient to provide proper space for the numbers
+showing latitude and longitude or township and range. A simple rule[8]
+for determining the width of this space is as follows: Divide the sum
+of the dimensions of the map by 2 and find the square root of the
+quotient, which will represent the width of the border in sixteenths
+of an inch. Example: Map is 20 by 30 inches; (20 + 30)/2 = 25; square
+root of 25 = 5; width of border = 5/16 inch.
+
+[Footnote 8: Worked out by Martin Solem, of the U. S. Geological
+Survey.]
+
+The numbers showing latitude and longitude should be in shaded arabic
+numerals and those showing township and range in gothic. The symbols
+for degree, minute, and second should not be crowded. On a map that
+has no added border lines the numbers should be in hair-line gothic.
+
+TITLE.
+
+The title of a map should be in roman letters and if placed at the
+lower margin should generally be arranged in two lines, unless it is
+short. If it forms two or more lines the lines should be well
+balanced. The first line should describe the position of the area; the
+second line should state the purpose of the map, as
+
+ MAP OF BUTTE AND VICINITY, MONTANA
+
+ SHOWING LOCATION OF MINES AND PROSPECTS.
+
+A title placed inside the border of a map should be arranged in a
+series of lines, generally beginning with "Map of" or "Geologic map
+of." and the line showing the dominant part of the title should be
+emphasized by larger lettering, thus:
+
+ =MAP OF=
+ THE VICINITY OF BUTTE
+ MONTANA
+ SHOWING LOCATION OF MINES AND PROSPECTS.
+
+The name of the author or compiler of a map or of the person supplying
+the geologic or other data shown on it may be placed either beneath
+the title or in the lower right corner, just below the border line,
+and the names of the topographers or the source of the base should be
+stated in the lower left corner, just below the border line. If the
+title is placed inside the border all notes giving credit for any part
+or features of the map may be placed beneath the title or scale. (See
+PI. VII.)
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE VII
+
+
+DETAILS OF THE MAKE-UP OF A GEOLOGIC MAP]
+
+EXPLANATION.
+
+The symbols, patterns, or colors used on a map should be given in a
+series of rectangles or "boxes," accompanied by explanatory terms in
+the form shown in Plate VII, headed "Explanation." If the explanation
+is small a convenient place for it on some maps may be found within
+the neat lines. If no space is available there, or if it is so large
+that there is not room to place it there without obscuring other
+details, it may be placed either vertically along the right margin, as
+shown in Plate VII, or horizontally under the title. A geologic
+explanation should preferably be arranged vertically, as in Plate VII,
+so as to show the relative age of the formations by the positions of
+the boxes. This explanation should be carefully worked out in pencil
+by the draftsman and approved by the committee on geologic names
+before it is drawn in ink, in order to save time in making
+corrections.
+
+In lettering the explanation roman letters or type should be used for
+the titles under the boxes and italic of smaller size for the
+subtitles or descriptive detail, which should be inclosed in
+parentheses. The names of geologic periods and systems should be in
+gothic capitals, the names of series or groups should be in italic
+lower case, and the limit of each period, system, or group should be
+indicated by braces. The general style and arrangement shown in the
+Survey's geologic folios should be followed, and this and the
+arrangement of other matter is shown in Plate VII. Care should be
+taken not to crowd the explanation, and if corrections are necessary
+they should be so made that each line of the matter in which they
+appear will be properly spaced.
+
+The explanation for a map that is to be engraved or to be reproduced
+by lithography need only be sketched in to show general style and
+arrangement. The engraver or the lithographer will supply such matter
+in proper form according to specifications. For direct reproduction,
+however, as by photolithography or zinc etching, the lettering must
+either be carefully drawn with pen or printed from type on slips,
+which are pasted on the drawing.
+
+GRAPHIC SCALES FOR MAPS.
+
+A bar scale for miles or feet should be given on every map, and if the
+map is of international interest the metric scale should be given just
+beneath the scale of miles or feet. The accepted designs for these
+scales are shown in figure 7. The scale should be accompanied by any
+necessary statement pertaining to the base map, such as "Contour
+interval 20 feet," "Datum is mean sea level." The fractional scale
+(1/250,000, for example) should be given on all except the more simple
+kinds of maps, and the date of publication should also appear just
+below the scale or scales. The single-line bar scale should be used
+only on small or simple maps. The length of the bar scale must depend
+on the size of the map and the space available. Those shown in figure
+7 were made over blue prints from scales used by the Survey.
+
+To make a bar scale for a map of unknown scale that shows only a
+single meridian and parallel, or for a map on which no meridians or
+parallels are shown, first ascertain the distance between two points
+shown on the map by reference to other authentic maps. If, for
+example, the distance between two such points is 16.315 miles draw a
+horizontal line (_a_ in fig. 8) representing this distance on the map,
+and at its end, at right angles to it, draw another line (_b_)
+actually measuring 16.315 units of any convenient denomination. Draw a
+straight line (c) diagonally between the ends of lines _a_ and _b_.
+Then set off on line _b_ any convenient number of the units selected,
+say 5 or 10, and project from the points set off lines exactly
+parallel with line _c_ to line _a_. The distance and the number of the
+units thus marked on line a will indicate the number of miles covered
+by that distance on the map, as shown in figure 8.
+
+[Illustration: Figure 7.--Designs for bar scales.]
+
+[Illustration: Figure 8.--Method of making a bar scale for a map of
+unknown scale.]
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE VIII
+
+
+PATTERNS USED TO SHOW DISTINCTIONS BETWEEN AREAS ON BLACK AND WHITE
+MAPS
+
+Contrasts may be increased by varying the direction and spacing of
+Lines]
+
+SYMBOLS.
+
+Symbols should be drawn with as much care as letters, though to a
+critic they may not appear so bad as poor lettering unless he finds
+them glaringly large or so small that he can discover or identify them
+only with difficulty. The size of a symbol must depend on its
+importance on the map bearing it. On a map that shows numerous mines,
+for instance, the crossed hammers or the symbols for shafts should be
+not only visible but conspicuous. The draftsman who is to make such a
+map must know beforehand how much his drawing will be reduced in
+reproduction and must make the symbols in proportion to the reduction.
+The symbols shown in Plate II (p. 20) should be used in all the
+Survey's illustrations where they are appropriate.
+
+AREAL PATTERNS FOR BLACK AND WHITE MAPS.
+
+The conventional patterns used on a map to distinguish separate areas,
+chiefly geologic, are shown in Plate VIII. The patterns shown
+represent the proper combinations of lines, dots, and other forms and
+should be spaced openly or closely according to the size of the area
+covered, the contrast needed between areas, and the general clearness
+and effect desired. If a map is to show both small and large areas
+dense or closely spaced patterns should generally be used for the
+smaller areas, even if they may be required for some fairly large
+areas representing the same formation or condition. On the other hand,
+open patterns should be used for large areas. Again, it may be
+necessary to make certain areas more conspicuous than others, and this
+effect can be best produced by drawing the lines closer together
+rather than by making them heavier, unless the area covered is small
+or unless a closely spaced similar pattern has been or will be used
+elsewhere on the map. Heavy-line patterns or bars are not desirable.
+The lines forming a pattern should generally be drawn at an angle of
+45° to the sides of the map; they should be drawn vertically or
+horizontally only in small areas or in areas not crossed by meridians
+or parallels or by other lines running in the same direction. The
+lines should preferably run across the long axis of an area, not
+parallel to it, and the predominating trend or general direction of
+the areas of one geologic formation on a map should decide the
+direction of the lines for all areas of that formation on the same
+map, even if the rule must be violated on some of the minor areas.
+
+An effort should always be made to produce a pattern that is
+subordinate in strength to the main lines of the base map on which it
+is drawn. In black and white maps, as in colored maps, unlike patterns
+should be placed next to each other. If they are so placed it may not
+be necessary to rule the lines on two adjacent areas in opposite
+directions to produce needed distinctions. A section liner or other
+ruling device should be used in drawing line patterns in order to
+produce uniformly even spacing. The application of six of these
+conventional patterns to a base map is shown in figure 9.
+
+[Illustration: Figure 9.--Map bearing six areal line patterns.]
+
+STANDARD COLORS FOR GEOLOGIC MAPS.
+
+The standard series of colors for systems of sedimentary rocks is
+shown on the maps in the Survey's geologic folios but is subject to
+modifications for use on maps in other Survey reports. Each system is
+represented by a different color, and if there are two or more
+formations in one system they are generally distinguished by using
+different patterns composed of straight parallel lines in the same
+color. The patterns for subaerial deposits (chiefly Quaternary) are
+composed of dots or circles, or combinations of both, and may be
+printed in any color, but the color most often used is yellow or
+ochraceous orange. No specific colors are prescribed for igneous
+rocks, but if only a few areas are shown red or pink is preferred. The
+colors used for igneous rocks are generally more brilliant and purer
+than those used for sedimentary rocks. For small areas they are used
+"solid"; for large areas they are reduced in tone by the use of a
+suitable cross-line pattern or "reticle." Metamorphic rocks are
+represented by short dashes irregularly placed. These dashes may be in
+black or in color over a ground tint or over an uncolored area, or
+they may be in white on a ground tint or pattern. The standard colors
+used for the sedimentary series covering the 12 systems recognized by
+the Geological Survey are: Quaternary (Q), ochraceous orange; Tertiary
+(T), _yellow ocher_ and _isabella color_; Cretaceous (K),
+_olive-green_ or _rainette-green_; Jurassic (J), _blue-green_ or
+_niagara-green_; Triassic (TR), _light peacock-blue_ or _bluish
+gray-green_; Carboniferous (C), _blue_ or _columibia-blue_; Devonian
+(D), _gray-purple_ or _heliotrope-gray_; Silurian (S), _purple_ or
+_argyle-purple_; Ordovician (0), _red-purple_ or _rocellin-purple_;
+Cambrian (-C), _brick-red_ or _etruscan red_; Algonkian (A), _terra
+cotta_ or _onion-skin pink_; Archean (AR), _gray-brown_ or _drab_.[9]
+
+[Footnote 9: Names printed in italic are from "Color standards and
+nomenclature," by Robert Ridgway.]
+
+REDUCTION OF ENLARGEMENT OF MAPS.
+
+The following is the simplest and most accurate method of marking the
+reduction or enlargement of a map to a selected scale: Measure the
+distance between the extreme meridians along one of the parallels.
+(See fig. 10.) Convert this distance into miles by multiplying the
+number of degrees it covers (say 3) by the number of miles in a
+degree. A degree on the forty-third parallel, for example, is 50.669
+miles,[10] which multiplied by 3 equals 152.007 miles. Then draw a
+line on the margin of the map, outside the border, the exact length of
+the 3 degrees, and just below this line draw another line representing
+the same number of miles (152.007) on the scale to which the map is to
+be reduced or enlarged. Then mark to reduce or enlarge the upper line
+to the lower line, as shown in figure 10. A long line will reduce
+error and give greater accuracy than a short one, and therefore as
+great a distance should be set off as possible. The number of miles
+represented by both lines and the fractional scale to which it is to
+be reduced should be stated on the drawing, for permanent record.
+
+[Footnote 10: See U. S. Geol. Survey Bull. 650, p. 37. 1916.]
+
+Maps that will bear reduction without affecting the clearness of the
+details they show may be reduced to fit the book in which they are to
+appear, regardless of definite scale. The reduction for such maps is
+best marked in fractions, as "1/2 off," "1/3 off," "2/3 off." If the
+size needed is not exactly represented by these fractions it should be
+indicated in inches, as "Reduce this line to 7-1/2 inches," or "Reduce
+to 4-3/8 inches in width."
+
+[Illustration: Figure 10.--Diagram showing method of marking maps for
+reduction or enlargement (for record).]
+
+
+DIAGRAMS.
+
+In preparing a diagram a draftsman should endeavor to make its parts
+and relations perfectly clear to the reader. He should study the
+drawing or material furnished by the author until he fully understands
+it and should endeavor to reproduce it simply and legibly. Any
+lettering that may be needed should generally be in plain upright or
+slanting gothic type (see Pl. IX), or it may be in roman.
+
+A diagram should generally be drawn on bristol board or on blue-lined
+section paper and should be marked for reduction to the minimum size.
+It should bear no title, as the title will be set up in type by the
+printer.
+
+
+SECTIONS.
+
+The sections used in geologic reports are of two widely different
+kinds. One shows only the broader relations of parts; the other shows
+details of structure as well as relations. One is diagrammatic; the
+other is more realistic and graphic. The draftsman should prepare all
+sections strictly according to the copy supplied by the author but
+should use proper symbols and make a more finished drawing. The
+various kinds of sections, most of them geologic, are described on
+pages 29-30, and the conventions used to express lithologic character
+are shown in Plate III.
+
+[Illustration: U. S. GEOLOGICAL SURVEY
+
+PREPARATION OF ILLUSTRATIONS PLATE VIII
+
+
+DIAGRAMS AND CURVES.]
+
+Detailed drawings of this kind, though entirely conventional, can be
+so prepared as to give a satisfactory expression of nature. The
+draftsman should study well-prepared sections in Geological Survey
+reports and should learn the details of folding and faulting from
+textbooks. He should first ascertain whether or not the vertical scale
+in the original section has been unduly exaggerated, and if so he
+should confer with the author with a view to reducing the exaggeration
+as much as possible. He should submit to the author all questions as
+to doubtful points, as well as all suggestions for improvement in
+expression, before he makes any changes, and he should make
+corrections only on the author's approval. A seeming inaccuracy in an
+author's drawing may be a faithful representation of natural
+conditions. For example, a formation that seems to be omitted by
+inadvertence in drawing may really "pinch out" at a point represented
+in the section. (See a on fig. 11.)
+
+[Illustration: Figure 11.--Structure section showing method of
+determining the secession of folds.]
+
+Penciled lines corresponding to those shown by dots in figure 11
+should be carefully added in redrawing a roughly sketched section that
+shows complex folding. An original indefinite sketch that shows
+complicated structure affords opportunities for error in preparing the
+new drawing, and omissions may be detected by following the formations
+as they would be continued above and below the section, as shown by
+the dotted lines in the figure.
+
+
+PLANS AND CROSS SECTIONS OF MINES.
+
+Plans of mines, like diagrams, should not be elaborate, and their
+lettering should be plain and legible, yet it should not be so
+conspicuous as to obscure other details. Gothic letters should
+generally be used, but some plans require different styles of
+lettering, especially for geographic or other names that should be
+coordinate with those on maps or other illustrations in the book.
+Unless there are good reasons, however, for varying the styles of
+lettering, plain gothic capitals, or capitals and lower-case letters,
+either upright or slanting, should be used. Abbreviations for the
+numbers of levels should generally be given thus: 3d level, 6th level,
+200-foot level, etc., or the shorter terms may be spelled out, as
+third level, sixth level. The same general scheme of lettering should
+be used on all plans and cross sections that are to appear in one
+publication or in one series of similar papers.
+
+The reduction of such drawings to the minimum scale consistent with
+clearness is always advisable.
+
+
+
+
+DRAWINGS OF SPECIMENS OF ROCKS AND FOSSILS.
+
+
+METHODS USED.
+
+Drawings of specimens or other objects were once made with brush and
+pencil or with pen and ink, by means of measurements taken with
+dividers or by viewing the specimen through a camera lucida. Each of
+these methods is still used, but by using the camera lucida in
+sketching: the outlines and details more accurate proportions and
+relations can be produced, whether the object is to be enlarged or
+reduced, than by any other means except photography.
+
+
+BRUSH AND PENCIL DRAWINGS.
+
+In all drawings or photographs of specimens, except photomicrographs
+of thin sections, the light should appear to come from the upper left
+quarter. A disregard of the well-established rule that the direction
+of illumination should be uniform throughout a series of drawings
+would cause confusion or uncertainty in the interpretation of the
+relief shown in them.
+
+Reynolds's three-ply and four-ply bristol board affords a satisfactory
+surface for brush and pencil drawings. Its surface is smooth and hard
+and, being free from coating of any kind, permits satisfactory
+erasures without great injury; its color is pure whits; and it is
+durable.
+
+Boss's relief hand-stipple paper is also well adapted to many kinds of
+brush drawings as well as to its primary use for producing stippled
+effects. Very delicate gradations of color or light and shade can be
+produced on its surface with brush and lampblack or with india ink,
+and high lights can be made by scraping off the chalky surface.
+
+The draftsman who is preparing brush and pencil drawings should have
+first of all a knowledge of the principles of light and shade, of
+reflected light, and (for drawing specimens) of shadow perspective. He
+should also have delicacy of touch and ability to see and interpret
+form and to reproduce the soft blending of light and shade shown in a
+good photograph. He should be provided with pencils equal in quality
+to the Koh-i-noor B, F, 4H, and 6H; the best quality of red sable
+brushes of the sizes of Winsor & Newton's Nos. 3, 4, and 6; the best
+quality of stick india ink; a cake or pan of lampblack; and a
+porcelain saucer or slab.
+
+In drawings of fossils and of some other specimens a combination of
+pencil and brush work produces satisfactory results and tends to
+increase speed. The gloss produced by penciling, however, is
+objectionable and should be obviated by a preponderance of brush work.
+Stick India ink is the best pigment to use in delicate wash drawings,
+and lampblack is preferable for large work on which the softer tones
+of the shading are not so important and for drawings that are to be
+considerably reduced when engraved. Gouache (an opaque mixture of
+Chinese white and lampblack) may also be used, but it is best suited
+for large work.
+
+In making corrections on brush drawings the parts to be corrected
+should be carefully washed out with a small short-cropped brush and
+water and still further cleaned by using a rubber eraser over an
+erasing shield or an opening cut in a piece of celluloid. Erasures
+should not be made on delicate work with a knife or a sand rubber, as
+either will injure the surface and affect reproduction. In measuring a
+specimen with dividers the draftsman should be careful not to injure
+the specimen or to puncture the paper on which he is preparing the
+drawing.
+
+
+PEN DRAWINGS.
+
+A draftsman who is preparing drawings of specimens with pen and ink
+should have a good assortment of pens equal to Gillott's Nos. 291,
+290, and 170, liquid waterproof ink equal to that manufactured by
+Higgins, good pencils, hard and soft rubber erasures, plain dividers,
+and Reynolds's bristol board. A glass eraser is also useful.
+
+Good pen drawings of specimens are much more difficult to make than
+brush drawings. They can be prepared only by a draftsman who has had
+some artistic training and experience in pen work. Few draftsmen can
+prepare pen drawings that faithfully represent both the detail and the
+texture of specimens; the shading on many such drawings confuses and
+destroys both detail and texture.
+
+The pencil sketch over which a pen drawing of a specimen should be
+made must be prepared in much the same manner as the sketch for a
+brush drawing, though the outlines need not be so delicate. This
+sketch is generally made on bristol board. The pen work should begin
+with the outlines and should then be carried to the details, and
+finally to the shading, whether in lines or stipple. The texture of a
+specimen is the best key to the proper shading. If the specimen is
+decidedly granular, stippling is appropriate; if it is smooth or
+polished, finely drawn parallel lines, varied in spacing and
+character according to depth of shade and texture, are preferable.
+Erasures can be made with a hard-rubber eraser, other parts being
+protected by a shield, or with a very sharp knife or a glass eraser,
+and the parts erased can be resurfaced with an agate burnisher.
+
+
+
+
+RETOUCHING PHOTOGRAPHS OF SPECIMENS.
+
+
+Photographs of specimens, particularly fossils that have been coated
+to destroy local color, should be printed on velox paper, in a tone
+somewhat lighter than that of ordinary photographs. The details and
+relief should, however, be strong enough to enable the draftsman to
+see them clearly, so that by retouching them and strengthening the
+shadows and high lights he can make them sufficiently strong for
+reproduction. This he can do by a combination of pencil and brush
+work, the pencil being used sparingly because the gloss produced by
+the graphite is likely to affect reproduction. A No. 3 Winsor &
+Newton's red sable brush and lampblack are preferable for the greater
+part of this work, and a 4H and a 6H pencil for the fine details and
+as a possible aid in producing the finer gradations of shading. The
+details should be retouched or strengthened under a reading glass to
+insure accuracy; the broader effects can be best produced without the
+aid of a magnifier.
+
+Erasures on photographs of specimens should be made very carefully
+with a hard rubber that is free from sand, and the parts not to be
+disturbed should be protected with a shield. High lights may be added
+by carefully scraping or rubbing the surface of the paper.
+
+
+
+
+LANDSCAPE DRAWINGS FROM POOR PHOTOGRAPHS.
+
+
+A poor photograph or one that has become injured and can not be
+retouched for direct reproduction can be utilized by making from it,
+as described below, a pen drawing or a brush or crayon drawing, which
+will be almost photographically correct.
+
+
+PEN DRAWINGS MADE OVER PHOTOGRAPHS.
+
+A pen and ink drawing may be made over a blue print or a bromide print
+(preferably a blue print) and the photographic image then bleached
+out. The blue print should be larger than publication size and should
+not be so dark that the draftsman can not see his lines. If the
+negative is available a bromide enlargement can be obtained; otherwise
+the picture should be rephotographed in larger size, preferably twice
+publication size. The enlargement will give the draftsman greater
+freedom in drawing details and will make his work appear finer and
+better in the reduced illustration. If the photographic print is of a
+subject requiring the use of instruments it should be securely
+fastened to a drawing board, square with the board, so that any
+horizontal and vertical lines in it may be ruled by the use of a =T=
+square and triangle. For specimen or landscape work it need not be
+fastened.
+
+For bleaching blue prints a saturated solution of oxalate of potassium
+(K2C2O4 + H2O) has been used with good results. For bleaching bromide
+prints cyanide of potassium (KCN) to which a few drops or flakes of
+iodine have been added should be used. Neither kind of print should be
+bleached until the drawing has been completely finished in every
+detail, because bleaching loosens the fibers of the paper, so that the
+ink of any added lines is likely to spread. The print should be placed
+in a hard-rubber pan, the bleaching solution poured on it, and the pan
+rocked until the image disappears. The print should then be carefully
+removed, thoroughly washed in running water, placed between clean
+white blotters to dry, and finally mounted on cardboard. For
+temporary, hurried work on drawings that are not to be retained for
+future use the blue print may be mounted first and bleached by pouring
+the bleaching fluid over the mounted print.
+
+
+BRUSH DRAWINGS FROM POOR PHOTOGRAPHS.
+
+Brush drawings may be made directly from photographs by working over
+an enlarged print with gouache, or by making a pencil tracing and
+sketch of the photograph and working it up with lampblack or india
+ink. The photograph should be larger than publication size to permit
+greater freedom and breadth in drawing details. The larger size will
+also afford a more refined and better engraving when reduced. If
+lampblack or india ink is used and the subject is small, bristol board
+is recommended, but if the photograph is larger than, say, 8 by 10
+inches, Whatman's hot-pressed double elephant or similar paper, laid
+down with thumb tacks, will prove satisfactory.
+
+If gouache is used over a print a preliminary drawing is of course
+unnecessary, but the photograph should be an unglazed print of a size
+that will require considerable reduction, and the finished drawing
+should be protected by an oversheet. If lampblack or india ink and not
+gouache is used the photograph should be traced and a fairly complete
+pencil sketch should be made before the brush is used.
+
+Plates I, IV, _A_, V, _B_, and VII, _B_, Monograph 34, were made from
+gouache drawings. Plates III, _A_, VII, _A_, X, XI, XII, XIII, XX,
+XXVIII, and XXX, in the same publication, were made from lampblack or
+india-ink wash drawings. The originals can be examined at any time.
+
+
+
+
+OUTDOOR SKETCHES.
+
+
+The art of sketching from nature is one in which few but professional
+artists excel. Not many geologists are able to make sketches from
+nature that are suitable for direct reproduction. An artistic
+draftsman should be able to redraw the geologist's sketches, however,
+in their true perspective and relations, with the skill necessary to
+make them satisfactory illustrations.
+
+In most crude outdoor sketches the important features are usually
+shown with sufficient clearness to follow. If they are not the
+draftsman should ascertain what those features are and prepare the new
+drawing in such a way as to display them properly. The new drawing
+should be made with pen and ink, generally for reduction to a text
+figure, which is the most appropriate form for such an illustration.
+
+In all sketches of this kind the lines should be drawn in such a way
+as to produce natural effects and at the same time to make good
+printing plates. Good examples of pen and ink sketches of this class
+can be found in Monograph 34, already referred to, and in the Seventh
+Annual Report, especially Plates XXVIII and XXXVIII; Ninth Annual
+Report, Plates XLIII and XLIV; Tenth Annual Report, Plates XIV and XIX
+and figure 58; Eleventh Annual Report, Plates XV, XXVII, XXXV, LII,
+and LIV and figures 18, 30, 31, 67, 98, and 99.
+
+
+
+
+DRAWINGS OF CRYSTALS.
+
+
+A crystal should generally be drawn in outline with straight lines.
+The invisible rear side of a crystal, if shown, should be represented
+by dashed lines. The outer boundary line of a crystal should be
+slightly heavier than the inside lines, which should all be of the
+same weight. Striations should be shown by straight lines; broken or
+uneven surfaces by irregular lines. A twinning line, if an
+intersection edge, should be solid; if not an intersection edge it
+should be broken into dashes. Italic, Greek, German, and Old English
+letters are used to mark crystal faces. All faces of a given form
+should be marked by the same letter but may be differentiated, if
+necessary, by primes or numerals, thus: m, m', m'', m''', m{'v}.
+"Leaders" should be short full lines, or, if these are likely to be
+confusing, they should be dashes. Numbers may be used in place of
+letters for specific purposes. Letters indicating twin faces are
+underscored; a second twin is doubly underscored or overscored, thus:
+m_, m=, m¯. Twin units may be differentiated by the use of roman
+numerals.
+
+
+
+
+RETOUCHING PHOTOGRAPHS.
+
+
+An author, of course, selects his photographs to illustrate some
+special features; he does not always consider their fitness for
+reproduction. Photographs that are blurred or out of focus, those in
+which the shadows are too black or lack transparency, and those which
+have local defects, such as bad skies or spots, must be worked over to
+make them suitable for reproduction. In order to remedy these defects
+and produce natural results the draftsman doing work of this sort
+should be able to see and interpret nature properly and to supply
+natural effects in a manner corresponding with those produced
+photographically. He should be sufficiently expert with the brush and
+pencil and in handling an air brush to duplicate the delicate and soft
+tones in the photograph, and he should know how the pigments he uses
+will "take" when the subject is reproduced.
+
+The retoucher should have access to an air brush and should provide
+himself with a jar of photo white or blanc d'argent and a color box
+containing indian red, crimson lake, yellow ocher, lampblack, and
+ultramarine--colors with which he can duplicate those shown in any
+photograph. He should also have the best grade of red sable brushes,
+ranging in size from No. 3 to No. 8, a stack of porcelain saucers, and
+a jar of oxgall. By mixing the colors to match exactly the shades of a
+photograph and using a red sable brush he can strengthen details,
+"spot out" flaws, and remove imperfections, except those in skies or
+other large, flat areas, for which he must use an air brush.
+
+The air brush has become a necessary adjunct to a retoucher's outfit.
+Smooth, even gradations of flat tones can not be successfully applied
+to photographs without it, and it is therefore indispensable,
+especially for retouching skies and covering other large areas.
+
+Before retouching a photograph the draftsman should mix in a saucer a
+tint that will match the color of the part that is to be retouched and
+should try this tint and note its effect after it has dried and change
+it, if necessary, until it matches the color exactly. If he is to
+retouch a number of photographs that have the same local color he may
+with advantage make up enough of the tint for the entire lot,
+thoroughly mixing it and seeing that it is not too thin. In making
+this tint he should use only pigments of the best grade, and if he
+finds that the Chinese or other white he is using does not photograph
+well, or that it does not hold its color, he should discard it at once
+and use another brand. Photographs that are to be retouched should be
+large enough to permit sufficient reduction to soften the effects of
+retouching.
+
+In order to eliminate the lines of junction between two or more
+photographs that are joined together to form a panorama some
+adjustment or fitting of details by retouching is generally required
+before the group is rephotographed to obtain a new print of the whole
+on one piece of paper. As it is often desirable to increase the width
+of such an illustration the photographer should be instructed to print
+the photograph on a strip of paper that is wider than the negative, so
+that, if necessary, the retouching may be carried above or below the
+new print to add depth to the illustration.
+
+Panoramas may also be drawn from photographs with either pen or brush
+in the manner described on pages 68-69.
+
+
+
+
+PART III. PROCESSES OF REPRODUCING ILLUSTRATIONS.
+
+
+
+
+METHODS EMPLOYED.
+
+
+The preliminary work in producing illustrations includes the
+preparation, from originals submitted by authors, of drawings and
+other kinds of "copy" in such a way that the copy can be reproduced in
+multiple by printing.
+
+Several processes are used for preparing plates for printing
+illustrations, and each has its peculiar features of excellence. One
+process may render fine details with facility but may fail in
+uniformity in large editions; another may be cheap and effective on
+the whole but may not reproduce fine details; and still another may
+give fine color or tone effects but may be too expensive. Therefore a
+knowledge of the varied uses and results and of the cost of the
+several processes of reproduction and, on the other hand, of the kinds
+of originals that are best suited for reproduction by any one of the
+processes is essential to effectiveness and economy in planning,
+preparing, and reproducing an illustration.
+
+The following condensed descriptions of processes are intended mainly
+to aid in determining the kind of copy that is appropriate for each
+process and the kind and quality of reproduction to be expected, so
+that only the principal operations or stages in each process are
+described. Wood engraving, which was used in making printing plates
+for many of the illustrations in the early publications of the
+Geological Survey, is described here only to compare that laborious
+and "indirect" method of engraving cuts with the more modern kinds of
+relief engraving. In 1892 it gave way to photo-engraving.
+
+
+
+
+PHOTO-ENGRAVING.
+
+
+GENERAL FEATURES
+
+The term "photo-engraving" is applied to processes by which a black
+and white line drawing, photograph, or like original is reproduced in
+relief on a metal plate from which prints may be made on an ordinary
+printing press, in distinction from processes that print from flat or
+relatively flat surfaces, such as the lithographic and photogelatin
+processes. The photo-engraving processes that are most generally used
+are those called "zinc etching" and "half-tone engraving." These
+processes depend on the discovery that gelatin or similar organic
+material, if treated with potassium or ammonium bichromate and exposed
+to the action of light, is made insoluble in water. If a metal plate
+coated with bichromatized gelatin or albumen is exposed to light under
+a negative the parts acted upon by light become insoluble and those
+not acted upon remain unchanged and may be washed away so as to expose
+the metal, which is then etched with acid in order to give relief to
+the unexposed parts and make of them a printing surface.
+
+
+ZINC ETCHING.
+
+Zinc etching is adapted to the direct reproduction of a pen and ink
+drawing composed of lines, dots, or solid black areas. On the finished
+metal plate these lines, dots, and solid areas form the printing
+surface, and the spaces between them, which have been etched away,
+represent the white or blank parts of the picture. The process is
+cheap and is almost universally used for reproducing small drawings
+designed for text illustrations. It is also well adapted to the
+reproduction of maps and diagrams measuring in print not more than
+about 10 by 14 inches. One of the chief advantages of this and of all
+other direct (photographic) processes of engraving is that they
+reproduce a drawing in facsimile, whereas the "personal equation" must
+enter into all engravings made by an indirect method--that is, by
+hand--such as wood engraving, wax engraving, and engraving on stone or
+copper, which make it necessary to compare every detail of the proof
+with every detail of the drawing before the engraving can be approved.
+The pen drawing to be reproduced, which should preferably be
+considerably larger than the completed engraving, is first
+photographed to the proper size or scale on an ordinary negative film.
+The film is then stripped from the negative and reversed in order that
+the etched plate may print the design as in the original and that the
+film may be grouped with other films on one large glass and all
+printed at the same time. The negative (whether a single film or
+several) is then placed in a specially constructed printing frame in
+contact under pressure with a sensitized zinc plate and exposed to
+light.
+
+After the zinc plate has been removed from the printing frame (in the
+dark room) the plate is rolled with printer's transfer ink, which
+resists acid, and placed in a shallow tray containing water, in which
+it is rocked for several minutes, and then taken out and rubbed gently
+with cotton. The parts of the coating of the plate that were acted on
+by light have become insoluble and will therefore be unaffected by the
+water, but the parts of the coating not acted on by light and
+therefore not hardened will be removed by the washing, which will
+expose the metal and leave the parts acted on by light--the
+picture--in black lines, dots, etc. The plate is then dusted with
+"topping powder," a resinous substance which adheres only to the parts
+carrying the ink. The plate is then heated so that the resin and the
+ink that remain fuse together and form, when cooled, a resistant
+surface which will not be affected by the acid to be used later in
+etching the unprotected parts of the plate.
+
+The plate is now ready for a preliminary etching in a fluid consisting
+of water and a few drops of nitric acid. It is placed in a tray,
+rocked gently for a short time, and then removed, washed well in
+running water, drained, and dried with gentle heat. "Dragon's blood,"
+a resinous powder that resists the action of acid, is next applied to
+the plate, in order to protect the sides of the lines and the dots
+from the acid, and the plate is then heated just sufficiently to melt
+the powder and units it with the ink. A small quantity of nitric acid
+is now added to the etching bath, and the plate is subjected to its
+first thorough biting or etching. It is then removed from the bath,
+washed under a tap, carefully wiped with a damp rag, and dried with
+gentle heat.
+
+The plate is thus treated three or more times until it is etched deep
+enough to insure satisfactory printing, and it is then ready for
+finishing, which consists of deepening the larger open spaces between
+the lines with a routing machine and of cutting away with hand gravers
+lines that are improperly connected or that are so close together that
+they will not print separately. The routing machine is provided with a
+cutting tool mounted on a revolving spindle that projects downward
+into the engraved plate, which is securely fastened. The movement of
+the arm that holds the cutter is universal and can be controlled with
+great precision. The plate is then "proved" that is, a proof is taken
+from it on paper and if the proof is satisfactory the plate is nailed
+to a block of wood on which it will be "type high" (0.918 inch), for
+printing.
+
+Most drawings for zinc etching are made with a pen in black ink and
+consist of lines, dots, or masses of black, but drawings may also be
+prepared by using some medium that will produce a fine stipple, such
+as a black crayon on rough paper or Ross's stipple paper. (See p. 24.)
+The drawing should be one and one-half to two or three times as large
+as the printed illustration, for it is impossible to obtain a
+satisfactory reproduction of a pen and ink drawing without some
+reduction. If the drawing has not been reduced the lines appear
+heavier in the reproduction than in the drawing, and imperfections
+thus become more noticeable; if it has been properly reduced,
+imperfections are diminished and the lines and dots become thinner and
+finer than those in the drawing. In making a drawing that is to be
+reduced the draftsman can also space his lines farther apart and work
+out his details more easily.
+
+An author should carefully examine and approve the finished drawings,
+which can, of course, be greatly altered, if necessary, before they
+are engraved; but similar corrections can not be made on proof sheets
+of zinc cuts, which should not be marked for alterations except by
+eliminating parts. Minor changes can be made in such a cut by an
+expert "finisher," but if the cut is small it is generally cheaper to
+correct the drawing and have a new cut made.
+
+Zinc etchings cost about 10 to 25 cents a square inch, the cost being
+varied according to a standard scale which is based upon the
+ascertained cost of reproduction. The minimum charge for a single cut
+is $2.
+
+
+COPPER ETCHING IN RELIEF.
+
+Copper etching, which produces a line cut in relief, requires the same
+kind of copy that is most often marked for zinc etching and is used to
+obtain deeper etching and a more permanent cut. It is said to produce
+better printing plates than those etched on zinc and is used largely
+for reproducing script lettering and other fine work. As copper plates
+will hold up longer in printing than zinc, a cut etched on copper may
+not need to be electrotyped.
+
+The chemical part of the process is practically the same as that
+employed for etching half-tone plates, described under the next
+heading.
+
+The cost of etching on copper is considerably greater than the cost of
+etching on zinc. This process is not often used in reproducing
+illustrations for publications of the Geological Survey.
+
+
+HALF-TONE ENGRAVING.
+
+The half-tone process is, in name at least, familiar to almost
+everyone who has had any connection with the making of books, whether
+as author, editor, illustrator, or printer. The invention of a
+photomechanical process of reproducing a line drawing to make a metal
+plate that could be printed along with type on an ordinary printing
+press naturally led to attempts to reproduce similarly a photograph.
+It was known that the intermediate shades between white and black in a
+photograph--the half tones--can be reproduced on an ordinary printing
+press only by breaking them up into dots or lines that will form a
+good printing surface and that by their variation in size or density
+will give for each shade the effect of a uniform tone. In the
+half-tone process this effect is produced by photographing the picture
+or object through a screen.
+
+The half-tone screen consists of two plates of glass, on each of which
+lines running generally at an angle of 45° to the sides of the plate
+have been engraved, cemented together so that the lines cross at
+right angles. The lines, which are minute grooves filled with an
+opaque black pigment, thus appear as a series of black crossed lines
+on a white ground. The screen is placed in the camera in front of the
+negative. Screens are made that show from 60 lines to an inch for the
+coarser newspaper illustrations to 250 lines or more to the inch for
+fine book work. The screens used for magazine illustrations generally
+show 120 to 150 lines. Those used for Survey publications show 150 to
+175 lines, and for reproducing delicate drawings and photographs of
+fossils screens bearing 200 lines to the inch are sometimes specified;
+but these finer screens require the use of highly super-coated papers,
+some of them made of cheap fiber and not known to be permanent. For a
+half tone that is to be printed in the text a 100-line or a 120-line
+screen is specified. (See Pl. VI, p. 56.)
+
+The method of etching a half-tone plate does not differ greatly from
+that used in zinc etching, and there are several kinds of half-tone
+plates, though most of them are etched on copper, not on zinc, those
+etched on zinc being used principally for newspaper illustrations. The
+half-tone screen is used also in other processes to obtain a negative.
+
+When a half-tone negative hag been made the film is stripped from the
+glass plate and reversed, as in the zinc-etching process, though some
+half-tone engravers use a mirror box or prism by which the picture is
+so disposed on the negative that it does not need stripping and
+reversing. A perfectly flat, clean, and highly polished copper plate,
+generally large enough to accommodate several such films, is then
+coated with a sensitive film according to one of several formulas, all
+based on the fact that gelatin or some similar body, if sensitized
+with certain chromic salts, becomes hardened and insoluble in water on
+exposure to light. This plate is then placed in the printing frame in
+contact, under pressure, with the glass negative plate and is exposed
+to light in the usual manner. The copper plate is then removed from
+the frame in the dark room and made ready for etching.
+
+For etching half-tone plates on copper a saturated solution of
+perchloride of iron is used instead of the solution of nitric acid
+used for zinc etching. The time of etching ranges from about 5 to 15
+minutes, according to the strength of the solution. One etching is
+generally sufficient, but it may be necessary to give the plate
+another "biting" if it has not been etched deep enough, or to re-etch
+it in order to strengthen contrasts. If, for instance, the sky in a
+half-tone plate shows too dark or is uneven in tint it can be made
+lighter or more even by re-etching. On the other hand, if certain
+features on a plate are too light they can be darkened by
+burnishing--rubbing the surface with a highly polished steel burnisher
+under just sufficient pressure to flatten slightly the fine points
+that form the printing surface of the plate. When the plate leaves the
+hands of the etcher it is turned over to the finisher, who with a
+graver removes spots or any other imperfections that may appear on it.
+Sometimes a roulette is used to lighten parts, and other tools are
+used for special purposes.
+
+After a plate that shows two or more pictures has been etched and
+finished it is divided by sawing them apart. Each one is then put into
+a beveling machine, where its edges are trimmed and the usual border
+is made, if it is desired. The separate plates are then ready to be
+proved and mounted on blocks of wood which make them type high, ready
+for printing.
+
+The half-tone process is used almost exclusively for reproducing
+photographs and wash drawings, though it will produce a facsimile of
+any kind of copy, such as impressions from type, old manuscripts, or
+typewriting, but a shade composed of minute black dots will appear
+over the entire print and there will be no absolutely whits areas
+unless they are produced by routing the plate or cutting out the high
+lights. (See p. 74.) The reproduction of an ordinary outdoor
+photograph requires very little handwork, except for re-etching,
+burnishing, and cutting the borders. In the reproduction of copy that
+is made up of separate parts, such as groups of photographs of
+specimens that are to appear on a white ground, the half-tone
+"tint"--or more properly shade--between and around the several figures
+must be removed and numbers must be added. This operation requires two
+negatives--one half tone and one line--and produces what is called a
+"combination" plate. Therefore the difference in the cost of making a
+half-tone cut from a single photograph of a landscape and from a cut
+made from "copy" of the same size consisting of a number of small
+photographs or drawings, to which numbers or letters are added, is
+considerable (about 50 per cent greater) and depends upon the amount
+of additional work involved. Routing, when needed, must be done with
+extreme care lest the edges of a figure be marred, and this work
+requires skill that can be gained only by experience.
+
+Copy for the half-tone process should be as nearly perfect as
+possible. Only the best photographs should be selected. Prints on
+semimat velox and glossy haloid papers are regarded as the best
+photographic copy for reproduction. Every part of the photograph or
+drawing should be absolutely clean. If any part that should be pure
+white becomes soiled or stained the defects will be reproduced. If a
+photograph needs retouching it should be retouched with great care and
+just sufficiently to correct defects and to bring out or strengthen
+the important details. In many photographs the skies may be "muddy" or
+uneven in tone, and this defect can be corrected by the use of an air
+brush, the only medium that will produce an almost even tone. As
+already stated, half-tone plates can be improved by re-etching and
+tooling, but tooling tends to destroy the effects of nature and
+produces an artificial appearance in the print. One who is preparing
+wash drawings for reproduction by the half-tone process should
+remember that brush marks and other inequalities of tone will be
+reproduced with as much fidelity as other details. Such drawings
+should therefore be made two or three times larger than the engraved
+cut in order to subdue all unnatural effects and to soften the general
+tones.
+
+Line drawings are not generally suitable copy for the half-tone
+process, but it is occasionally desirable to use that process instead
+of zinc etching for reproducing a line drawing that has been
+inexpertly prepared if the cost of redrawing would more than offset
+the difference in cost between zinc etching and the more expensive
+half-tone process. In reproducing a pen drawing by half tone the lines
+become softened and represent the details and shading only; but the
+pen drawing may be further developed by brush work. Examples of this
+type of reproduction are Plates V, _A_, VI, _A_, and XV, figure 10,
+and other illustrations in Survey Monograph 34.
+
+Vignetting, which consists of a skillful grading off of the edges of a
+picture, as well as extensive tooling or hand engraving, is often
+employed for artistic effect but should be specified only for
+exceptional illustrations. The plates made for the Survey are either
+"square trimmed" or the ground tint is entirely omitted or routed
+away; they are not usually tooled or vignetted.
+
+Half-tone cuts etched on copper cost 20 to 60 cents a square inch, the
+cost being varied according to a standard scale based on the
+ascertained cost of reproduction. Those that require a screen finer
+than 150 lines cost 25 per cent additional. The minimum charge for a
+single cut is $3.
+
+Half tones etched on zinc (100-line screen or coarser) cost 25 per
+cent less than those etched on copper.
+
+
+THREE-COLOR HALF-TONE PROCESS.
+
+The three-color process is practically an adaptation of the half-tone
+process to color printing based on the theory that all colors or hues
+in nature can be reproduced by combinations of three colors of the
+spectrum--red, blue, and yellow. The process differs from the ordinary
+half-tone process particularly in the use of color filters in making
+the negatives and in the character of screens and diaphragms used.
+This process, like all others, is worked somewhat differently in
+different establishments. In what is called the indirect method, the
+one most commonly used, twelve photographic operations are necessary
+to produce one illustration, or the three plates or cuts from which
+one illustration is to be reproduced by printing. These twelve
+operations produce three chromatic negatives, each representing one
+color; three transparencies or positives, made from the chromatic
+negatives; three half-tone negatives, made from the positives; and
+finally three contact prints, made on sensitized metal plates. In what
+is called the direct method the half-tone screen is placed in front of
+the photographic plate so that it becomes also a half-tone negative
+from which a print is made on a sensitized metal plate. Thus the
+photographic operations in the direct method are reduced to six, but
+the interference to the passage of light offered by the half-tone
+screen and by the prism used to reverse the image on the negative
+lengthens the time of exposure.
+
+Unfortunately, no pigments have been found that can reproduce in
+purity the colors of the spectrum, and to this fact is due the failure
+of the process to reproduce exactly all the colors, tints, and shades
+of an original. When a drawing in black on white paper is photographed
+only the white paper affects the negative film. The transparent parts
+of the developed negative thus represent the black, and the opaque
+parts, which have been acted upon by light, represent the whits.
+Theoretically, when a chromatic negative is made for the yellow plate
+a purple-violet filter cuts out all the yellow and allows the red and
+blue rays to affect the plate; when a negative is made for the blue
+plate an orange filter similarly cuts out the blue and allows the
+yellow and red rays to affect the plate; and when a negative is made
+for the red plate a green filter cuts out the red and permits the blue
+and yellow rays to affect the plate. These color filters, which are
+usually made of transparent stained gelatin, are generally placed in
+front of the lens. When printing plates like those used in the
+half-tone process have been made from the three negatives and the
+plates have been inked with yellow, blue, and red ink, respectively, a
+combined impression from them will produce a close approximation of
+the subject photographed. The colored inks often used are light
+yellow, peacock or prussian blue, and bright, transparent crimson.
+
+The ordinary half-tone screen, which bears lines cut at an angle of
+45° to the sides of the plate, is rectangular, but the screens used
+for three-color work are made circular in order that they may be
+turned in the camera to make the lines intersect at other angles, the
+angles being varied to avoid producing an undesirable pattern or a
+moire effect. Turning the screen also prevents the exact coincidence
+or superposition of the red, blue, and yellow dots, which would
+produce black. In other respects the screens do not differ essentially
+from those used in ordinary half-tone work.
+
+As special experience is necessary in printing three-color plates the
+engraver generally delivers the printed illustrations to the purchaser
+instead of the plates, which he furnishes for other kinds of relief
+printing.
+
+The copy for this process may consist of anything in color, such as
+specimens, objects, paintings, or properly colored photographs. The
+process does not usually reproduce all the colors and tints of an
+original with equal exactness and is not used by the Survey for work
+that demands precise reproduction of color, but it is satisfactory for
+reproducing most colored drawings, colored photographs of specimens,
+or the specimens themselves if they show individual variations in
+color. As the process is entirely photomechanical it gives more
+scientific accuracy in detail than chromolithography, in which there
+is much hand work, and it is much less expensive. If the colors shown
+in proofs are not satisfactory they can be modified.
+
+The four-color process, in which four color plates are used, gives a
+closer approximation of true color values than the three-color
+process, and at a comparatively small increase of cost. The additional
+color used is generally a neutral gray or black.
+
+
+
+
+WAX ENGRAVING (THE CEROTYPE PROCESS).
+
+
+The wax or cerotype process does not require finished drawings and is
+especially suitable for making text illustrations and small maps,
+although it may be used also for large work. For this process blue
+prints, pencil sketches, old prints, or rough copy of any kind may be
+submitted--that is, it is not necessary to furnish carefully prepared
+drawings in black ink, as it would be for photo-engraving, for the wax
+engraver will reproduce in proper form any illustration in which the
+copy and the instructions show what is wanted, just as an experienced
+draftsman will make a good drawing from the rough original furnished
+by an author. Full and clear instructions should always be given,
+however, as to the size of the cut wanted and what it is to show.
+
+In this process a polished copper plate is coated with a film
+consisting of beeswax, a whitening medium, and other ingredients, and
+the coating, which varies in thickness according to the nature of the
+copy, is sensitized as in the ordinary photographic processes. The map
+or other design to be engraved is first photographed to publication
+size and a contact print is made on the wax coating from the negative.
+The lines and other parts of the photographed image are then traced or
+cut through the wax to the copper plate with steel tools and
+straightened or perfected by the engraver, but the lettering is set in
+printer's type, which is pressed into the wax until it also touches
+the metal plate. After the work of cutting through the wax has been
+completed the larger open spaces between the lines are "built up" by
+the addition of wax to give greater depth to the plate, so that the
+wax plate thus built up corresponds to an electrotype mold. The plate
+is then dusted with powdered graphite and suspended in a solution
+containing copper, where by electrolytic action a copper shell is
+formed over its surface. When this shell is sufficiently thick it is
+removed from the solution and reinforced on the back with metal, and
+proofs are taken from it. If the proofs are satisfactory the plate is
+blocked type-high.
+
+Wax-engraved plates may be used for printing colored maps or diagrams,
+in which variations of tint are produced by various kinds of machine
+rulings. The effect of some of the colors thus produced is almost a
+"flat" tint, in which a pattern can be detected only by close
+scrutiny. Some color work is printed from a wax base plate in
+combination with half-tone color plates.
+
+The price of a wax engraving depends entirely on the size of the cut,
+the amount of work involved, and the character of the original copy,
+but it should not exceed very much the cost of a carefully prepared
+pen drawing plus the cost of a zinc etching made from it. Cuts
+engraved by the wax process, like zinc and half-tone plates, are
+delivered to the purchaser. If colored work is ordered, however, the
+printed sheets, not the cuts, are delivered.
+
+
+
+WOOD ENGRAVING.
+
+
+Wood engraving was once the universal method of producing cuts for
+illustrations that were designed to be printed on an ordinary press.
+It is said to be the oldest of all methods of engraving illustrations.
+The engraving is made on a block of boxwood, a very dense, hard wood
+of a light-yellow color. The block is cut type-high across the grain,
+and the engraving surface is made perfectly smooth by nibbing it with
+pumice or other stone. When a cut is to be larger than 3 or 4 inches
+square the wood block is made up of pieces securely dovetailed or
+joined together to prevent splitting and warping. A woodcut is not
+used for printing but is electrotyped and the electrotype is used in
+the press.
+
+Originally the smoothed surface of the wood block was coated with
+prepared chalk or Chinese whits, and on this coating a finished
+drawing was made with a brush and pencil by an illustrator. According
+to more recent practice the surface of the wood is covered with a
+sensitized coating, on which the drawing or design to be engraved is
+photographed. The engraver then, with various kinds of gravers and
+other tools, cuts out the parts of the picture that are to be
+represented by white paper and leaves the lines, dots, and black areas
+as a printing surface, thus translating the shades and tints of the
+picture into a system of lines and dots which exactly duplicate, in
+effect, the details and tones of the original design. In order to
+produce a line effect of an area in which the tone is intermediate
+between whits and black the engraver must space his lines so that
+one-half the area will remain as printing surface and the other half
+as white spaces, and he must give character and direction to his
+lines, so that, if he is skillful, he can reproduce not only the
+delicate tones but the texture and details of the original picture.
+Many wood engravers became noted for their artistic rendering of
+magazine illustrations, of famous paintings, and of other works of
+art.
+
+The Survey began to abandon this method of engraving in 1884, when the
+Sixth Annual Report was in press, substituting for it the cheaper
+photomechanical processes, zinc etching and half-tone engraving, and
+entirely abandoned its use in 1892.
+
+Many good examples of wood engraving may be found in the early
+monographs and annual reports of the Geological Survey. Monograph 2
+contains numerous examples.
+
+
+
+PHOTOGELATIN PROCESSES.
+
+
+Bichromatized gelatin is used in several photomechanical processes of
+reproducing illustrations, but in the photogelatin processes the
+gelatin not only receives the image by exposure to light through a
+negative but becomes a printing surface on a plate from which prints
+are made somewhat as in lithography. The several photogelatin
+processes are much the same as the original collotype process and are
+best known by the names collotype, heliotype, albertype, artotype, and
+the German name lichtdruck.
+
+In working these processes a thick plate of glass, after certain
+preliminary treatment, is coated with sensitized gelatin. The plate is
+then placed in a drying room or oven having a temperature of 120° F.,
+baked until it is thoroughly dry, and allowed to cool gradually. The
+subject to be reproduced is then photographed in the usual manner, and
+unless a prism or mirror box has been used the negative is stripped
+and reversed in order to make the print reproduce the original in
+proper position. From the negative a contact print is made on the
+gelatin-coated plate, the parts or molecules of gelatin being hardened
+in proportion to the amount of light that affects them. After the
+contact print has been made the gelatin plate is thoroughly washed in
+cold water, in order to dissolve and wash out the bichromate and stop
+any further action of light on the plate, and is then thoroughly
+dried. Before prints are made from the gelatin-coated plate water is
+flowed on it and penetrates different parts of the gelatin according
+to their hardness. The darkest parts of the picture will correspond to
+the hardest and densest parts of the gelatin, which will not absorb
+water; the lighter parts will take up more water. The surface water
+is then removed with a rubber straight edge and an absorbent roller
+and the plate is ready for inking. The ink, being greasy, has no
+affinity for water, and when it is rolled over the plate it adheres
+only to the dry parts of the gelatin, and in the press is carried to
+the paper in all the lights and shades of the illustration. The plate
+is kept moist in printing.
+
+The paper used for printing from photogelatin plates must be free from
+chemicals that will affect the gelatin. A nearly pure rag paper is
+generally used.
+
+The photogelatin process is well adapted to the reproduction of
+paleontologic drawings, wash drawings, photographs, photomicrographs,
+works of art, old manuscripts--in fact, any kind of subject in which
+the reproduction of delicate lights and shades is essential. If
+properly manipulated it has distinct advantages over the half-tone
+process in that it can reproduce details and light and shade without
+showing the effect of a screen and without the use of coated paper.
+Excellent reproductions by the heliotype process are also made in
+color by first printing the design in a neutral tone and superposing
+appropriate transparent colors on this print, somewhat as in
+chromolithography, so that the colors softly blend with the shaded
+groundwork.
+
+Reproductions made by the photogelatin process are more expensive than
+those made by the half-tone process, for the prints are generally made
+on better paper and are printed with greater care. They give no screen
+effect and are perhaps unrivaled by prints obtained by any other
+process except photogravure, in which the image is printed from a
+metal plate that has been sensitized, exposed under a reversed
+negative, and etched.
+
+Changes can not be made on photogelatin plates except by making over
+the corrected parts. All retouching must be done on the originals or
+on the negatives made from then.
+
+
+
+
+LITHOGRAPHY.
+
+
+ORIGINAL PROCESS.
+
+The general term "lithography" is sometimes used to indicate not only
+the original process so named, said to have been invented by
+Senefelder, but chromolithography, photolithography, and engraving on
+stone, as well as engraving on copper as a means of supplying matter
+to be transferred to and printed from a lithographic stone.
+
+Senefelder discovered that limestone will absorb either grease or
+Water, and that neither one will penetrate a part of the surface
+previously affected by the other. He found that if a design is drawn
+on limestone with a greasy crayon and the stone afterward properly
+prepared with a solution of nitric acid and gum, greasy ink will
+adhere only to the parts that are covered with the crayon, and that
+the stone will give off an impression of the design.
+
+Lithographic stone is described as a fine, compact, homogeneous
+limestone, which may be either a pure carbonate of lime or
+dolomitic--that is, it may contain magnesium. Although limestone is
+one of the most common rocks, limestone of a quality suitable for use
+in lithography is found at only a few localities.[11] There are two
+general classes of lithographic stone, known to the trade as "blue" or
+hard stone and "yellow" or soft stone. The blue stone is adapted for
+engraving and to the better grade of fine-line printing; the yellow
+stone is rated as somewhat inferior.
+
+[Footnote 11: Kubel, S. J., Lithographic stone: U. S. Geol. Survey
+Mineral Resources, 1900, pp. 869-873, 1901.]
+
+In the original process, which may here be termed plain lithography,
+two methods are employed in putting on stone the design to be
+reproduced. In one the subject or picture to be reproduced is drawn on
+the printing stone either with a lithographic crayon or with a pen
+dipped in lithographic ink or "tusche," which is oily or fatty, like
+the crayon. In the other method the drawing is made on transfer paper
+and transferred to the stone. In drawing on stone it is necessary to
+reverse the design, so that all lettering must be drawn backward. In
+doing this the artist often uses a mirror to aid him. If the drawing
+is made on transfer paper the design and the lettering are copied as
+in the original--not reversed.
+
+Before a drawing is made on stone a stone of the quality suited to the
+particular design in hand is selected. The stone is then ground and
+polished, and if the drawing is to be made with crayon it is "grained"
+according to the special requirements of the subject. If the drawing
+is to be made with a pen and is to consist of "line work" the stone is
+polished. The first step is to obtain on the stone an outline or
+"faint" of the design. There are several ways to do this. By one
+method a tracing of the design is made, a sheet of thin paper covered
+with red chalk is laid face downward on the stone, the tracing is laid
+face downward over it, and the design is again traced in red-chalk
+lines on the stone. The method described is simple, but there are
+others that are more complicated and that are particularly applicable
+to the reproduction of photographs and other illustrations. Crayon
+work is often used in combination with pen and ink, stipple, and brush
+work. This method of drawing on stone is used also for preparing color
+stones in the process of chromolithography, in which there are many
+added details of manipulation. After the drawing has been made on the
+stone or transferred to it the stone is "gummed"--that is, it is
+covered with a solution of gum arabic and nitric acid--and dried. The
+stone is then dampened with water and carefully rolled with
+lithographic ink, which adheres to the pen or crayon work and is
+repelled elsewhere. It is then "rubbed" over with powdered rosin and
+talcum, which adheres to the ink and further protects the drawing from
+the effects of the etching fluid, which is next to be applied to the
+stone. This fluid consists of a 10 per cent solution of gum arabic to
+which 2 to 7 per cent of nitric acid has been added, the degree of
+acidity being varied according to the subject and the hardness of the
+stone. The fluid is applied with a brush or sponge and is left on the
+stone just long enough to decompose slightly the carbonate of lime on
+its surface and, after washing, to leave the design or drawing in very
+slight relief. The stone is again gummed and dried, and the design is
+"washed out" or brought out by removing the surface gum with a wet
+sponge and applying to the stone a rag sprinkled with turpentine and
+charged with printing ink. These operations wash away the tusche and
+the crayon that have been decomposed by the acid and expose the design
+faintly in white at first, but it gradually grows darker as it becomes
+charged with printing ink from the rag. The stone is next "rolled up"
+or inked. The slightly moistened surface repels the ink and the design
+takes it up, so that when the stone is run through the press the
+design is carried to the paper.
+
+Lithographic prints from stones prepared in this way are made on a
+flat-bed press. The stone is carried forward to print and on its
+return is dampened and inked, an operation slower than that of rotary
+printing.
+
+Corrections and changes are made on the stone by carefully scraping or
+polishing away the parts to be corrected and making the changes with a
+crayon or pen, but the design can not ordinarily be corrected twice in
+the same place, as the scraping or polishing removes a part of the
+surface of the stone and thus lessens the pressure at that place, and
+the impression there may be imperfect or may completely fail.
+
+This form of lithography is seldom used for Survey illustrations but
+was formerly much used and is well adapted to the reproduction of
+drawings of fossils, particularly of remains of dinosaurs and other
+types of large extinct animals. Examples may be seen in Monographs 8
+and 10 and in other early reports of the Geological Survey. The
+drawings for these illustrations were made directly on stone.
+
+A drawing made on one stone may be transferred in duplicate or in any
+desired number to another stone, or to a properly grained sheet of
+zinc and aluminum, from which impressions may be printed on a
+lithographic press. Both these metals are also used for lithographic
+printing on rotary presses, the zinc or aluminum plate being bent and
+secured around a cylinder which rotates continuously in one direction.
+As one impression is made at each revolution of the cylinder the
+printing is rapid; but the best printing from a metal plate is
+inferior to the best printing from a lithographic stone.
+
+
+PHOTOLITHOGRAPHY.
+
+Photolithography, like other lithographic processes, has been improved
+greatly during the last few years--not particularly in results but in
+methods--by the introduction of metal plates, the rubber blanket
+offset, the Ben Day films, and many mechanical and chemical devices,
+so that a brief description of it will not explain the process except
+in a most general way. As photolithography is a direct process and is
+relatively cheap it is the one most used for reproducing large maps
+and other line drawings that have been carefully prepared. Zinc and
+aluminum plates are now much used in photolithography, for a direct
+contact photographic print can be made on them, they can be printed
+flat or bent for use on a rotary press, and they can be stored for
+future use more economically than stones.
+
+There are two somewhat distinct methods of producing photolithographs.
+In both the ordinary photographic methods are used, but it is often
+necessary to "cut" or trace parts of the negative in order to open up
+lines and other features that are not sharp or well defined, so that
+the negative will print them sharp and clear. If the copy to be
+reproduced shows three colors, three negatives are made, one for each
+color, and the parts to be shown by each are preserved by "opaquing"
+or painting out all other parts. By the older method the negative thus
+perfected is placed in a printing frame in contact, under pressure,
+with sensitized transfer paper and is exposed to light. The printing
+frame is then carried to the dark room and the paper is removed from
+the frame and its surface covered with transfer ink. The paper is then
+laid face upward on water and soaked for several minutes, after which
+it is placed in the same position upon a slab of stone or metal and
+thoroughly washed with water. This washing removes the ink and the
+sensitive film from the parts that were unaffected by the action of
+light (the parts corresponding to the white paper in the design), but
+the ink still adheres to the lines of the design in the precise
+sharpness and clearness of the negative. The design is now ready to be
+transferred to the printing stone or zinc plate. The sheet is again
+slightly dampened between moist blotters and laid face downward in its
+correct position on a prepared stone or zinc plate, which is then
+pulled through a press under heavy pressure. The paper is then removed
+from the stone or plate, to which it has carried the design. From this
+point the gumming, etching, and other operations are practically the
+same as those used in ordinary lithography.
+
+The bichromate-gelatin transfer process described above has been
+replaced in the Survey by a more satisfactory one, which insures
+absolute scale and reproduces the finest line drawings perfectly
+without thickening the lines or without distortion. In this process,
+which is known as the planographic process, a photographic negative of
+the "copy" is placed in a vacuum printing frame in contact with a zinc
+or aluminum plate that has been sensitized with a bichromate-albumen
+solution and exposed in front of an arc lamp. After proper exposure
+the plate is removed from the frame, inked over, and placed under
+water. The parts not hardened by the action of light (the unexposed
+parts) are then rubbed away with cotton, and the plate is chemically
+etched, gummed over, and dried. The plate is then ready to be printed
+from in a lithographic press. If a large map is to be reproduced it is
+photographed in parts, and contact prints are made on zinc plates.
+From these plates transfers are pulled and the parts are assembled and
+laid down in proper position on a stone or an aluminum plate, which is
+then prepared for printing.
+
+A drawing that is to be reproduced by photolithography should be made
+on pure-white paper in lines, dots, or black masses with black
+waterproof ink. It should be one and one-half to two or three times
+the size of the finished print.
+
+Photolithography is particularly adapted to the reproduction of maps,
+plans, and other large drawings. Within certain limitations, lines may
+be changed and details may be added after proofs have been submitted.
+The process is ordinarily used for reproducing illustrations in one
+color (black), but it is used also for printing in more than one
+color, generally over a black outline base, each color being printed
+from a separate stone, as in chromolithography.
+
+
+OFFSET PRINTING.
+
+In the offset process the design is "offset" from a lithographic plate
+or stone to a rubber blanket on a cylinder, from which it is printed.
+By thus obtaining an impression from an elastic surface the finest
+details can be printed on rough, uncoated paper, which can not be used
+in other processes, which can be folded without danger of breaking,
+and which is more durable than coated paper. Plates II, III, IV, VII,
+and VIII in this pamphlet were printed by this process.
+
+
+CHROMOLITHOGRAPHY.
+
+The chromolithographic process, by which illustrations are printed in
+color from stone, is used in Survey publications principally for
+reproducing geologic maps, but it is sometimes used for reproducing
+colored drawings of specimens.
+
+There are several kinds of color printing from stones. One produces a
+picture by superimposing colors that combine and overlap without
+definite outlines and thus reproduce the softly blended colors of the
+original. Another reproduces the original by printing colors within
+definite outlines on a "base" which has been previously printed in
+black. The first kind is used by the Survey for reproducing colored
+drawings of specimens. The second is followed in reproducing geologic
+maps.
+
+As each color must be printed from a separate stone and properly
+fitted with respect to the others a tracing from the original is made
+of the precise outlines of each color; or, if the design is to be
+reduced, a tracing is made over a properly reduced photographic print.
+This tracing can be made on specially prepared tracing paper or on a
+sheet of transparent gelatin or celluloid, which is laid over the copy
+and on which all the outlines and overlaps of the various colors are
+scratched with a steel point. The scratches thus made on the celluloid
+are filled with red chalk or like substance, and rubbed in with
+cotton, and by reversing the sheet and rubbing it the chalk lines are
+deposited on as many stones as are needed to produce the colors of the
+original design, each stone bearing all the outlines of the design.
+Sometimes all the outlines are engraved on what is called a key stone
+and an impression from it is laid down on each of the color stones.
+The parts on each stone that are to have one color are then inked in
+or engraved, and at the same time guide marks are indicated, so that
+in the composite print from the stones each color will fit its proper
+place. This fitting is called "register" and is an important part of
+printing, for each stone must be adjusted to a nicety while on the
+press in order to make each impression fit the others exactly. The
+process was originally manipulated entirely by hand, but photography
+has now replaced much of the handwork and has given rise to several
+methods by which the same kinds of subjects are reproduced in
+radically different ways. Tints are sometimes produced by the
+half-tone and other screens and by machine ruling, and printer's type
+is used almost exclusively for titles and other matter that was
+formerly engraved or drawn on the stone.
+
+In reproducing a geologic map the base may be engraved on stone or on
+copper or it may be photo-lithographed. By either process the map may
+be transferred to the printing stone. The color stones for geologic
+maps are prepared by hand, but the geologic patterns, which are
+printed in colors, are engraved separately on plates, from which
+impressions are pulled when needed and transferred to their proper
+places on the printing stones in the shapes required according to the
+"key" design. The lighter, more transparent colors are generally
+printed first, and often twelve or more colors and many distinctive
+patterns are used to produce a geologic map. When proofs of such a map
+are pulled each stone must be taken up and carefully adjusted on the
+press, so that the work of proving maps that are printed from a
+considerable number of color stones is laborious and expensive.
+It is therefore customary to approve first combined proofs
+conditionally--that is, subject to the corrections and changes
+indicated on the proofs--and to hold the lithographer responsible for
+any failure to make the corrections.
+
+This process is the most expensive one used for reproducing
+illustrations. Changes may be indicated on proofs, but changes can not
+be made on a stone twice in the same place without danger of affecting
+the printing or making it necessary to retransfer the parts affected.
+All changes are expensive because a slight modification at one point
+may involve corresponding changes on a number of stones, each of which
+must be taken up, corrected, and proved to insure the exact
+coincidence of the parts affected. It is often less expensive to
+retransfer the entire job than to make extensive changes on the
+original stones.
+
+
+ENGRAVING ON STONE AND ON COPPER.
+
+Engraving on stone is distinctly lithographic, but engraving on copper
+is sometimes included among lithographic processes because the work
+produced by it is usually printed from stone and thus becomes
+lithographic. In other respects engraving on copper is not a
+lithographic process. Roughly prepared maps and any rough line copy
+that is accurate in statement and clear as to intent are appropriate
+for both methods of engraving, but drawings that are expertly prepared
+are more suitable for reproduction by photolithography. In engraving
+on stone the lines of a design are scratched on the blackened surface
+of a stone with a steel-pointed tool; in engraving on copper the lines
+are cut with a graver on a sheet or plate of copper, the matter to be
+engraved being first shown on the plate by what is called the
+photo-tracing process, which was devised in the Geological Survey.
+There is, however, no great or essential difference in the printed
+results of the two processes, but most lithographers employ only stone
+engravers.
+
+A stone on which a design is to be engraved is ground and polished
+according to the kind of work to be engraved, is coated with a thin
+solution of gum arable and allowed to dry, and is then washed until
+the superficial gum is removed while the surface pores remain filled.
+As the lines made by the engraver must be visible the stone is
+blackened with a pigment composed of lampblack and gum or is covered
+evenly with red chalk or Venetian red. It is then ready to receive the
+design to be engraved.
+
+If the design is a map which is to show culture, streams, and surface
+contours, and each of these sets of features is to be printed in a
+separate color, impressions of the work to be engraved must be placed
+on three stones. One method of doing this is to make a scratch tracing
+of the original drawing on a sheet of transparent gelatin or celluloid
+in the manner employed in chromolithography, except that a dry
+pigment, generally chrome-yellow, is used to fill the scratch lines
+instead of red chalk or Venetian red. From this tracing a "faint" or
+imprint of all the details of the three separate features of the map
+is made on each of the three stones, and the engraver then cuts on
+each stone only the lines and other features, including ample register
+marks, that are to be printed in one color, the imprint made from the
+tracing making it possible to engrave each set of features in its
+exact position relative to the other two. By another method the matter
+to be engraved is photographed directly on the stone.
+
+The engraving is done with a steel needle inserted in a small wooden
+cylinder, an instrument resembling an ordinary lead pencil. The size
+and shape of the needles used are varied according to the requirements
+of the matter to be engraved. With this instrument the lines and
+lettering are lightly scratched into the stone through the dark
+coating and show as light lines. The points of some of the needles are
+fine; those of others are V-shaped; and some have spoon-shaped points,
+for use in thickening lines and shading letters. All features are
+engraved in reverse.
+
+After the engraving is completed the stones are prepared for printing
+by wiping off all the superficial color and filling the engraved lines
+with a greasy ink--generally a thin printing ink--which is rubbed into
+the lines with a soft rag. Impressions are then pulled on transfer
+paper and transferred to three printing stones for use in printing the
+three colors, the register marks enabling the pressman to fit each
+color exactly in its proper place.
+
+In all lithographic processes the titles and other marginal lettering
+can be and usually are transferred from type impressions to the
+printing stones. It is therefore unnecessary to letter such matter
+carefully on an original drawing that is made for lithographic
+reproduction, for appropriate faces of type will give better printed
+results than hand lettering.
+
+Corrections can not be made on a stone or copper engraving as readily
+as on a drawing. If a stone engraver makes an error or if a change is
+required after his engraving is finished, the parts to be corrected
+must be scraped off and a new ground laid before the correction can be
+made. Sometimes he will engrave the parts corrected on another part of
+the original stone and transfer it to the printing stone. Corrections
+are made on copper plates by "hammering up" the plate from beneath,
+polishing off a new surface, and reengraving the part to be corrected.
+
+
+
+
+APPENDIX.
+
+
+The matter given in this appendix is much used in making geologic maps
+and other illustrations. The Greek alphabet and the groups of signs
+presented are given chiefly to show the correct formation of each
+letter and sign.
+
+
+
+
+MISCELLANEOUS TABLES.
+
+
+_Length of 1° of longitude measured along given parallels from the
+Equator to the poles._
+
+[From U. S. Coast and Geodetic Survey Report for 1884, Appendix 6.]
+
+ Parallel of Statute | Parallel of Statute | Parallel of Statute
+ latitude. miles. | latitude. miles. | latitude. miles.
+ ----------------------+-----------------------+----------------------
+ 0 69.172 | 31 59.365 | 61 33.623
+ 1 69.162 | 32 58.716 | 62 32.560
+ 2 69.130 | 33 58.071 | 63 31.488
+ 3 69.078 | 34 67.407 | 64 30.406
+ 4 69.005 | 35 66.725 | 65 29.315
+ 5 68.911 | 36 66.027 | 66 28.215
+ 6 68.795 | 37 65.311 | 67 27.106
+ 7 68.660 | 38 64.679 | 68 26.988
+ 8 68.504 | 39 63.829 | 69 24.862
+ 9 68.326 | 40 53.063 | 70 23.729
+ 10 68.129 | 41 62.281 | 71 22.589
+ 11 67.910 | 42 51.483 | 72 21.441
+ 12 67.670 | 43 60.669 | 73 20.287
+ 13 67.410 | 44 49.840 | 74 19.127
+ 14 67.131 | 45 48.995 | 75 17.960
+ 15 66.830 | 46 48.136 | 76 16.788
+ 16 66.510 | 47 47.261 | 77 15.611
+ 17 66.169 | 48 46.372 | 78 14.428
+ 18 65.808 | 49 45.469 | 79 13.242
+ 19 65.427 | 50 44.652 | 80 12.051
+ 20 65.026 | 51 43.621 | 81 10.857
+ 21 64.606 | 52 42.676 | 82 9.659
+ 22 64.166 | 53 41.719 | 83 8.458
+ 23 63.706 | 54 40.749 | 84 7.256
+ 24 63.228 | 55 39.766 | 85 6.049
+ 25 62.729 | 56 38.771 | 86 4.842
+ 26 62.212 | 57 37.764 | 87 3.632
+ 27 61.676 | 58 36.745 | 88 2.422
+ 28 61.122 | 59 35.716 | 89 1.211
+ 29 60.548 | 60 34.674 | 90 .000
+ 30 59.956 | |
+
+_Length of 1° of latitude measured along a meridian at given
+parallels._ [Parallel given is in center of the degree whose length is
+stated.]
+
+ Parallel of Statute
+ latitude. miles.
+ ----------------------
+ 0 68.704
+ 10 68.725
+ 20 68.786
+ 30 68.879
+ 40 68.993
+ 50 69.115
+ 60 69.230
+ 70 69.324
+ 80 69.386
+ 90 69.407
+
+
+Metric system and equivalents.
+
+[The units of linear measure most commonly used are millimeters (mm.),
+centimeters (cm.), decimeters (dm.), meters (m.), and kilometers
+(km.), 1 m. = 10 dm.; 1 dm. = 10 cm.; 1 cm. = 10 mm.; 1 km. = 1,000
+meters = 0.62137 mile; 1 m. = 39.37 inches = 3.280833 feet.]
+
+
+ Meters. | Inches. || Meters. | Feet. || Kilometers. | Miles.
+ ----------+-------------++---------+-----------++-------------+---------
+ 1 | 39.37 || 1 | 3.280633 || 1 | 0.62137
+ 2 | 78.74 || 2 | 6.561667 || 2 | 1.24274
+ 3 | 118.11 || 3 | 9.842500 || 3 | 1.86411
+ 4 | 157.48 || 4 | 13.123333 || 4 | 2.48548
+ 5 | 196.85 || 5 | 16.404166 || 5 | 3.10685
+ 6 | 236.22 || 6 | 19.685000 || 6 | 3.72822
+ 7 | 275.59 || 7 | 22.965833 || 7 | 4.34959
+ 8 | 314.96 || 8 | 26.246666 || 8 | 4.97096
+ 9 | 354.33 || 9 | 29.527500 || 9 | 5.59233
+
+ Inches. | Centimeters.|| Feet. | Meters. || Miles. | Kilometers.
+ ----------+-------------++---------+-----------++-----------+------------
+ 1 | 2.54 || 1 | 0.304801 || 1 | 1.60935
+ 2 | 5.08 || 2 | 0.609601 || 2 | 3.21869
+ 3 | 7.62 || 3 | 0.914402 || 3 | 4.82804
+ 4 | 10.16 || 4 | 1.219202 || 4 | 6.43739
+ 5 | 12.70 || 5 | 1.524003 || 5 | 8.04674
+ 6 | 15.24 || 6 | 1.828804 || 6 | 9.65606
+ 7 | 17.78 || 7 | 2.133604 || 7 | 11.26543
+ 8 | 20.32 || 8 | 2.438405 || 8 | 12.87478
+ 9 | 22.86 || 9 | 2.743205 || 9 | 14.48412
+
+The "vara," used in Texas, is equivalent to 33-1/3 inches and is
+computed as representing 2.78 feet.
+
+
+_Geologic eras, periods, systems, epochs, and series._
+
+
+ Era. Period or system. Epoch or series.
+
+ { { Recent.
+ { Quaternary. { Pleistocene (replaces "Glacial").
+ Cenozoic. {
+ { { Pliocene.
+ { Tertiary. { Miocene.
+ { { Oligocene.
+ { { Eocene.
+
+ { { Upper (Gulf may be used
+ { { provincially).
+ { Cretaceous. { Lower (Comanche and Shasta may be
+ { { used provincially).
+ {
+ { { Upper.
+ Mesozoic. { Jurassic. { Middle.
+ { { Lower.
+ {
+ { { Upper.
+ { Triassic. { Middle.
+ { { Lower.
+
+ { { Permian.
+ { { Pennsylvanian (replaces "Upper
+ { Carboniferous. { Carboniferous").
+ { { Mississippian (replaces "Lower
+ { { Carboniferous").
+ {
+ { { Upper.
+ { Devonian. { Middle.
+ { { Lower.
+ {
+ Paleozoic. { Silurian.
+ {
+ { { Upper (Cincinnatian may be used
+ { { provincially).
+ { Ordovician. { Middle (Mohawkian may be used
+ { { provincially).
+ { { Lower.
+ {
+ { { Saratogan (or Upper Cambrian).
+ { Cambrian. { Acadian (or Middle Cambrian).
+ { { Waucoban (or Lower Cambrian).
+
+ { Algonkian. }pre-Cambrian.
+ Proterozoic. { Archean. }
+
+
+_Chemical elements and symbols._
+
+ Element. Symbol. Element. Symbol. Element. Symbol.
+
+ Aluminum Al Holmium Ho Rhodium Rh
+ Antimony Sb Hydrogen H Rubidium Rb
+ Argon Al Indium In Ruthenium Ru
+ Arsenic As Iodine I Samarium Sa
+ Barium Ba Iridium Ir Scandium Sc
+ Bismuth Bi Iron Fe Selenium Se
+ Boron B Krypton Kr Silicon Si
+ Bromine Br Lanthanum La Silver Ag
+ Cadmium Cd Lead Pb Sodium Na
+ Cesium Cs Lithium Li Strontium Sr
+ Calcium Ca Lutecium Lu Sulphur S
+ Carbon C Magnesium Mg Tantalum Ta
+ Cerium Ce Manganese Mn Tellurium Te
+ Chlorine Cl Mercury Hg Terbium Tb
+ Chromium Cr Molybdenum Mo Thallium Tl
+ Cobalt Co Neodymium Nd Thorium Th
+ Columbium C Neon Ne Thulium Tm
+ Copper Cu Nickel Ni Tin Sn
+ Dysprosium Dy Niton Nt Titanium Ti
+ Erbium Er Nitrogen N Tungsten W
+ Europium Eu Osmium Os Uranium U
+ Fluorine F Oxygen O Vanadium V
+ Gadolinium Gd Palladium Pd Xenon Xe
+ Gallium Ga Phosphorus P Ytterbium
+ Germanium Ge Platinum Pt (Neoytterbium) Yb
+ Glucinum Gl Potassium K Yttrium Y
+ Gold Au Praseodymium Pr Zinc Zn
+ Helium He Radium Ra Zirconium Zr
+
+
+_Greek alphabet._
+
+ Caps. Lower-case. Greek name. English sound.
+ [Greek: A] [Greek: a] Alpha. A.
+ [Greek: B] [Greek: b] Beta. B.
+ [Greek: G] [Greek: g] Gamma. G.
+ [Greek: D] [Greek: d] Delta. D.
+ [Greek: E] [Greek: e] Epsilon. E short.
+ [Greek: Z] [Greek: z] Zeta. Z.
+ [Greek: H] [Greek: h] Eta. E long.
+ [Greek: Th] [Greek: th] Theta. Th.
+ [Greek: I] [Greek: i] Iota. I.
+ [Greek: K] [Greek: k] Kappa. K.
+ [Greek: L] [Greek: l] Lambda. L.
+ [Greek: M] [Greek: m] Mu. M.
+ [Greek: N] [Greek: n] Nu. N.
+ [Greek: X] [Greek: x] Xi. X.
+ [Greek: O] [Greek: o] Omicron. O short.
+ [Greek: P] [Greek: p] Pi. P.
+ [Greek: R] [Greek: r] Rho. R.
+ [Greek: S] [Greek: s] Sigma. S.
+ [Greek: T] [Greek: t] Tau. T.
+ [Greek: U] [Greek: u] Upsilon. U.
+ [Greek: F] [Greek: f] Phi. F.
+ [Greek: Ch] [Greek: ch] Chi. Ch.
+ [Greek: Ps] [Greek: ps] Psi. Ps.
+ [Greek: Om] [Greek: om] Omega. O long.
+
+
+_Roman numerals._
+
+ I 1 | IX 9 | LXX 70 | D 500
+ II 2 | X 10 | LXXX 80 | DC 600
+ III 3 | XIX 19 | XC 90 | DCC 700
+ IV 4 | XX 20 | C 100 | DCCC 800
+ V 5 | XXX 30 | CL 150 | CM 900
+ VI 6 | XL 40 | CC 200 | M 1000
+ VII 7 | L 50 | CCC 300 | MD 1500
+ VIII 8 | LX 60 | CD 400 | MCM 1900
+
+
+Mathematical signs.
+
+ + plus. ~ difference
+ - minus. integration.
+ × multiplied by. equivalence.
+ ÷ divided by. : ratio.
+ = equality. geometrical proportion.
+ ± plus or minus. -: difference, excess.
+ square. therefore.
+ rectangle. because.
+ triangle. infinity.
+ circle. varies as.
+ angle. radical.
+ right angle. ° degree.
+ or > greater than. ' minute.
+ or < less than. " second.
+ perpendicular.
+
+
+
+
+NAMES OF ROCKS.
+
+
+The following list was prepared in the geologic branch for the use of
+geologic draftsmen to enable them to select appropriate symbols for
+rocks that may be referred to in preliminary drawings by name only.
+For sedimentary rocks dots and circles, parallel lines, and broken or
+dotted lines are used; for metamorphic rocks short dashes arranged
+without definite patterns; and for igneous rocks patterns composed of
+short dashes, triangles, rhombs, crosses, and cross lines. All these
+patterns are shown in Plate III.
+
+
+_Sedimentary material._
+
+[Including residual, detrital, eolian, glacial, organic, and
+chemically precipitated material.]
+
+
+ Agglomerate. Ironstone (also igneous).
+ Alabaster. Itacolumite.
+ Alluvium. Kame.
+ Alum shale. Kaolin.
+ Anhydrite. Laterite.
+ Apron (alluvial). Lignite.
+ Argillite. Limestone.
+ Arkose. Limonite.
+ Asphalt. Loess.
+ Bench gravel. Marble (also metamorphic).
+ Bentonite. Marl.
+ Boulder clay. Metaxite.
+ Brea. Morainal deposit.
+ Breccia. Mudstone.
+ Brownstone. Novaculite.
+ Burrstone. Peat.
+ Calcarenite. Pelite.
+ Calc sinter. Phosphate rock.
+ Caliche. Phosphorite.
+ Catlinite. Phthanite.
+ Chalk. Psammites.
+ Chert. Psephites.
+ Clay. Puddingstone.
+ Coal. Pyroclastic material.
+ Conglomerate. Quartzite (also metamorphic).
+ Coprolite. Reddle.
+ Coquina. Rock salt.
+ Detritus. Rock stream.
+ Diatomaceous earth. Rubble.
+ Diluvium. Salt.
+ Dolomite. Sand.
+ Drift. Sandstone.
+ Fan (alluvial). Selenite.
+ Fanglomerate. Shale.
+ Flagstone. Silt.
+ Flint. Slate (also metamorphic).
+ Freestone. Soil.
+ Fuller's earth. Stalactite.
+ Geyserite. Stalagmite.
+ Gravel. Talc.
+ Graywacke. Talus.
+ Greensand. Till.
+ Grit. Travertine.
+ Gumbo. Tripoli.
+ Gypsum. Tufa (=chemically deposited lime).
+ Hardpan. Tuff (=igneous fragments).
+ Hematite. Wacke.
+ Infusorial earth. Wash.
+
+
+_Metamorphic material._
+
+ Adinole. Hornstone.
+ Amphibolite. Itabirite.
+ Andalusite schist (?). Kinzigite.
+ Apo (rhyolite), etc. Knotenschiefer.
+ Argillite. Knotty schists.
+ Augen gneiss (also igneous). Luxulianite (igneous?).
+ Biotite schist. Marble.
+ Calc schist. Meta (diabase), etc.
+ Cataclastic. Mica schist.
+ Chlorite schist Mylonite.
+ Clay slate. Ophicalcite.
+ Damourite schist. Ottrelite schist.
+ Desmosite. Phyllite.
+ Dynamometamorphic rock. Porcelanite.
+ Eclogite. Protogene.
+ Epidosite. Pyroschists.
+ Erlan. Quartz.
+ Erlanfels. Quartzite.
+ Eulysite. Quartz schist.
+ Fibrolite schist Schist.
+ Garnet rock. Sericite schist, etc.
+ Garnet schist. Serpentine.
+ Gneiss. Slate.
+ Granite gneiss. Soapstone.
+ Graywacke (?). Sodalite.
+ Green schists. Spilosite.
+ Greenstone (also igneous). Steatite.
+ Greisen. Talc schist.
+ Halleflinta. Topazfels.
+ Hornblende schist Topaz rock.
+ Hornfels. Zobtenite.
+
+
+_Igneous material._
+
+ Absarokite. Dolerite.
+ Abyssal. Dunite.
+ Adamellite. Durbachite.
+ Adendiorite. Effusive rock.
+ Ailsyte. Ekerite.
+ Åkerite. Elvan.
+ Alaskite. Enstatite.
+ Albitlte. Eruptive rock.
+ Allivalite. Essexite.
+ Allochetite. Estrellite.
+ Alnölte. Eulysite.
+ Alsbachite. Extrusive rock.
+ Ambonite. Farrisite.
+ Amherstite. Felsite.
+ Analcitite. Felsophyre.
+ Andesite. Fergusite.
+ Anorthosite. Fortunite.
+ Aphanitite. Fourchite.
+ Aplite. Foyaite.
+ Arkite. Gabbro.
+ Atatschite. Gauteite.
+ Augen gneiss (also metamorphic). Garewaite.
+ Augitite. Glumarrite.
+ Avezacite. Gladkaite.
+ Banakite. Granite.
+ Banatite. Granitite.
+ Bandaite. Granitoid.
+ Basalt. Granodiorite.
+ Basanite. Granophyre.
+ Beerbachite. Greenstone (also metamorphic).
+ Bekinkinite. Greisen (?).
+ Bombs. Grorudite.
+ Borolanite. Harrisite.
+ Bostonite. Harzburgite.
+ Camptonite. Haüynophyre.
+ Carmeloite. Hawaiite.
+ Cascadite. Hedrumite.
+ Chibinite. Heumite.
+ Ciminite. Holyokeite.
+ Comendite. Hornblendite.
+ Complementary rocks. Hypabyssal rock.
+ Coppaelite. Hyperite.
+ Cortlandite. Hypersthenite.
+ Cromaltite. Ijolite.
+ Cumberlandite. Intrusive rock.
+ Cuselite. Irruptive (=Intrusive) rock.
+ Dacite. Isenite.
+ Dellenite. Jacupirangite.
+ Diabase. Jumillite.
+ Diallagite. Kaiwekite.
+ Dike rock. Kedabekite.
+ Diorite. Kentallenite.
+ Ditroite. Kenyite.
+
+_Igneous material._--Continued.
+
+ Keratophyre. Perlite.
+ Kersantite. Phanerite.
+ Kimberlite. Phonolite.
+ Kobalaite. Pierite.
+ Krablite. Pitchstone.
+ Krageröite. Plagiaplite.
+ Kulaite. Plagioclastic.
+ Kyschytymite. Plumasite.
+ Lamprophyre. Plutonic rock.
+ Latite. Pollenite.
+ Laugenite. Porphyry.
+ Laurdalite. Pulaskite.
+ Laurvikite. Pumice.
+ Lava. Pyroxenite.
+ Lestiwarite. Rhombenporphyry.
+ Leucite basalt. Rhyolite.
+ Leucite tephrite. Rizzonite.
+ Leucitite. Rockalite.
+ Leucocratic. Santorinite.
+ Lherzolite. Sanukite.
+ Limbergite. Saxonite.
+ Lindoite. Scyelite.
+ Liparite. Shastaite.
+ Litchfieldite. Shonkinite.
+ Lithoidite. Shoshonite.
+ Luciitss. Soda granite.
+ Lujaurite. Sölvsbergite.
+ Madrupite. Sommaite.
+ Maenaite. Spessartite.
+ Magma basalt. Sussexite.
+ Malchite. Syenite.
+ Malignite. Taimyrite.
+ Mangerite. Tawite.
+ Mariupolite. Tephrite.
+ Melaphyre. Teschenite.
+ Melilite basalt. Theralite.
+ Mesanite. Tilaite.
+ Mica peridotite. Tinguaite.
+ Minette. Tjosite.
+ Missourite. Tonalite.
+ Monchiquite. Tonsbergite.
+ Mondholdeite. Tordrillite.
+ Monmouthite. Toscanite (?).
+ Monzonite. Trachy-andesite.
+ Mugearite. Trachyte.
+ Naujaite. Trap.
+ Nelsonite. Troctolite.
+ Nephelinite. Umptekite.
+ Nevadite. Unakite.
+ Nordmarkite. Ungaite.
+ Norite. Urtite.
+ Obsidian. Valbellite.
+ Odinite. Venanzite.
+ Orbite. Verite.
+ Orendite. Vitrophyre.
+ Ornöite. Vogesite.
+ Orthophyre. Volcanic rock.
+ Ortlerite. Volhynite.
+ Ouachitite. Vulsinite.
+ Paisanite. Websterite.
+ Pantellerite. Wehrlite.
+ Pegmatite. Windsorite.
+ Peridotite. Wyomingite.
+ Perknite. Yamaskite.
+
+
+
+
+INDEX.
+
+
+
+ A.
+
+ Abbreviations, forms of. 55-67
+ Adhesive materials, choice. 37
+ Alaska, maps of, reuse of. 17
+ Albertype. _See_ Photogelatin processes.
+ Apparatus, photographs of, preferred to sketches. 29
+ Approval of finished drawings, features to be covered by. 38
+ of illustrations, regulations governing. 80
+ Areas, patterns used to distinguish. 23
+ patterns used to distinguish, plate showing. 62
+ Army, Corps of Engineers of the, maps published by. 15
+ Artotype. _See_ Photogelatin processes.
+ Atlases, published, use of. 15
+
+
+ B.
+
+ Base maps. _See_ Maps, base.
+ Bleaching photographic prints, method and solutions for. 69
+ Border for maps, width and use of. 57-58
+ Bristol board, kind Mid sizes used. 24,66
+ Brash and pencil drawings, materials and methods used
+ in making. 66-67, 69
+ Brushes, kinds and sizes used. 66-67,71
+
+
+ C.
+
+ Celluloid transferring, process of. 47
+ requisitions for. 47
+ Cerotype process, description and advantages of. 80-81
+ Changes in engravings, possible kinds of. 38-39, 90
+ Changes in original material, draftsman to consult author on. 65
+ Chemical elements, names and symbols of. 98
+ Chromolithography, description of. 87-80
+ Civil divisions, lettering of. 53, 54
+ Coal beds, indication of thickness of. 31
+ Coast and Geodetic Survey charts, use of. 15
+ Collotype. _See_ Photogelatin processes.
+ Coloring materials, use of. 26
+ Colors, standard, for geologic maps. 62-63
+ use of, for ground-water features. 21-23
+ on original geologic maps. 27-28
+ Commas, form of. 54
+ use of, in numbers. 54
+ Contours, drawing of. 48-50
+ Cooperation, mention of. 13
+ Copper, engraving on. 89, 90
+ etching in relief on, process and advantages of. 75
+ Copying methods of. 46-48
+ Corrections. _See_ Changes.
+ Cost of photo-engravings. 75, 78, 80, 81
+ County maps, use of. 15
+ Crayons, wax, use of. 26, 50, 51
+ Credit for data of maps, indication of. 13
+ Crystals, drawings of, making and lettering of. 70
+ Cultural features, lettering of. 53-54
+ list of. 52-53
+ Curves, date showing. 64
+ Cuts. _See_ Engravings.
+
+
+ D.
+
+ Details of a geologic map, plate showing. 58
+ Diagrams, drawing and lettering of. 64
+ features of, plate showing. 64
+ original, general requirements for. 28-20
+ Director of the Survey, order by. 9
+ Divisions of plates and figures, serial letters and numbers for. 12
+ Drafting table, shadowless, description of. 47-48
+ shadowless, use of. 29, 48, 50
+ Draftsmen, detail of, to aid author. 9
+ detail of, to prepare base maps. 13-14
+ experience and reading required by. 41-42
+ general treatment of material by. 42-43
+ Drainage features, depiction of. 51-52
+ Drawing instruments, list of. 42
+ Drawing materials, kinds used. 23-26, 66-67, 69, 71
+ Drawings, authors', draftsmen may aid in making. 9
+ authors', editorial revision of. 38
+ finished, general requirements for. 41-42
+ requests for photographs of. 34
+ Duplicates of engravings, charges for. 38
+
+
+ E.
+
+ Effectiveness of illustrations, elements that produce. 7, 30
+ Electrotypes of engravings, charges for. 38
+ Elements, chemical, names and symbols of. 93
+ Engraving on stone, process of. 89-90
+ _See also_ Lithography.
+ Engravings, changes in. 38-39
+ original, time of keeping. 37
+ Erasers, injury to paper by. 67
+ kinds used. 25, 67-68
+ Erasures, smoothing paper after. 68
+ Explanations on maps, arrangement and lettering of. 19, 58-50
+
+
+ F.
+
+ Figures, differences from plates. 10-11
+ divisions of, serial letters for. 12
+ methods of inserting, plate showing. 12
+ Formations, geologic, use of letter symbols for. 20-21
+ Fossils. _See_ Specimens.
+ Four-color process, advantage of. 80
+
+
+ G.
+
+ Gas wells, symbols for. 21
+ Generalization, true, meaning of. 17
+ Geographic tables and formulas (Bull. 650), use of. 44, 45
+ Geologic periods of time, names of. 92
+ Gouache, use of. 67, 69
+ Great Lakes surveys, maps published by. 15
+ Greek letters, forms, names, and English sounds of. 93
+ Ground-water features, symbols representing. 21-23
+
+
+ H.
+
+ Hachuring, use of. 50
+ Half-tone engraving, preparation of copy for. 77-78
+ process and advantages of. 75-78
+ three-color process of. 78-80
+ Half tones, changes in. 39
+ prints of, showing effects produced by different screens. 56
+ requirements for printing. 11
+ Heliotype. _See_ Photogelatin processes.
+ Hill shading, use of. 60-51
+ Hydrographic features, lettering of. 54
+ representation of. 51-52
+ Hypsographic features, lettering of. 54
+
+
+ I.
+
+ Illustrations, kinds of. 10-11
+ Inks, kinds used. 25, 67
+ methods of using. 25
+ Inserting plates and figures, methods of, plate showing. 12
+ Instruments, draftsmen's, list of. 42
+
+
+ J.
+
+ Japanese transparent water colors, use of. 26
+
+
+ L.
+
+ Land Office maps, scales and detail of. 14-15
+ Latitude, length of 1° of, at intervals of 10°. 91
+ Lending of photographs and drawings, rules governing. 34
+ Letter symbols, use of, on geologic maps. 20-21
+ Lettering, directions for. 53-55
+ for lithographing. 90
+ for names of streams. 52, 54
+ on diagrams. 64
+ on drawings of crystals. 70
+ on original maps. 19
+ on plans and cross sections of mines. 65-66
+ reduction sheet used in, plate showing. 54
+ use of type for. 54-55
+ Light, direction and gradation of. 66
+ Lithographs, printing and insertion of. 11
+ Lithography, original process of. 83-85
+ _See also_ Engraving on stone.
+ Longitude, length of 1° of, at latitudes 0° to 90°. 91
+
+
+ M.
+
+ Map of the world, millionth-scale, use of, for base maps. 14
+ Maps, areal patterns for, drawing of. 61-62
+ bar scales for. 59-60
+ base, conventional symbols used on. 45-46
+ including new data, how obtained. 13-14
+ indication of sources on. 13
+ of the United States on small scales, use of. 15
+ published maps available for. 14-17
+ reuse of, to be approved. 13
+ black and whits, patterns used on, plate showing. 62
+ borders for. 57-68
+ cultural features on. 52-53
+ enlargement and reduction of. 18
+ explanations for. 19, 58-59
+ geologic, details of, plate showing. 58
+ printing of. 87-89
+ standard colors for. 62-63
+ hydrographic features on. 61-52
+ lettering on. 53-65
+ materials used for drawing. 23-28
+ orientation of. 18
+ original, margin required on. 19
+ original base, amount of detail on. 17
+ must be free from colors and symbols. 28
+ preparation of. 13-14, 17-18
+ original geologic, method of coloring. 27-28
+ projection for. 18-19, 43-45
+ reduction or enlargement of, marking for. 63-64
+ relief on. 48-51
+ standard scales for. 18
+ symbols used on. 20-23
+ drawing of. 61
+ plates showing. 20, 46
+ titles for. 58
+ topographic, scales of. 14-15
+ Mathematical signs, forms and names of. 94
+ Measures, linear, metric equivalents of. 92
+ Measuring scales for map projection, use of. 44
+ Meridians used on public-land maps, diagram showing. 16
+ Metric measures, English equivalents of. 92
+ Millionth-scale map, use of. 14
+ Mine plans, conventional lines for. 29
+ features of. 65-66
+ symbols used on, plate showing. 20
+ Minerals. _See_ Rocks.
+ Mississippi River Commission, maps published by 15
+
+
+ N.
+
+ Names of rocks. 94-97
+ National forest maps and proclamations, use of. 15
+
+
+ O.
+
+ Offset process, description of. 87
+ Oilwells, symbols for. 21
+ Opaquing, meaning of. 18, 47, 86
+ Orientation of maps, requirements for. 18
+ Original drawings, general treatment of, by draftsmen. 42-43
+ preparation of. 12-40
+ Outdoor sketches, redrawing of. 69-70
+
+
+ P.
+
+ Panoramas, construction of. 71
+ Paper, kinds used for drawings. 23-24, 60, 61, 66, 69
+ Pastes, use of. 37
+ Patterns, areal, method of drawing. 61-62
+ areal, plate showing. 62
+ Pen drawings, materials and methods used in making. 67-68, 68-69
+ Pencils, colored, use of. 26
+ drawing, quality and grades of. 25, 66
+ Pens, kinds of, used for drawing. 25, 48, 67
+ Photoengraving, cost of. 75, 78, 80, 81
+ general features of. 72-73
+ Photoengravings, printing and insertion of. 11
+ Photogelatin processes, description of. 82-83
+ Photographs, adaptation of. 83
+ bleaching of. 69
+ care needed in taking and handling. 32, 33, 39-40
+ copyrighted, consent for use of. 33-34
+ duplicate prints of, requests for. 34
+ mounting and numbering of. 33, 36-37
+ poor, mating of drawings over. 68-69
+ preparation of, for half-tone engraving. 77-78
+ record of source of. 34
+ selection of. 32-33
+ retouching of. 68, 70-71
+ suitability of. 9
+ unpublished, issue and use of. 34
+ Photolithographs, changes in. 39
+ Photolithography, description of. 86-87
+ Planographic process, description of. 87
+ Plans of mines, drawing and lettering of. 29, 65-66
+ symbols used on, plate showing. 20
+ Plates, differences from figures. 10-11
+ divisions of, serial letters and numbers for. 12
+ grouping small illustrations on. 36-37
+ methods of inserting, plate showing. 12
+ Political divisions, lettering of. 53, 54
+ Post-route maps, scales and detail of. 15
+ Projection for maps, preparation and checking of. 18-19, 43-45
+ Proofs, changes in. 76
+ correction of. 38-39
+ duplicate, supplying of. 30
+ submittal of. 38
+ Public-land maps, meridians, parallels, and township lines used on,
+ diagram showing. 16
+ Public works, lettering of. 53
+ Punctuation marks, forms of. 54
+ Purpose of illustrations in Survey reports. 8, 40
+
+
+ R.
+
+ Railroad surveys, data for maps obtainable from. 15
+ Railroads, names of, on maps. 57
+ Reduction of maps, marking drawings for. 63-64
+ means of. 18
+ Reduction sheet for lettering, plate showing. 54
+ use of. 55
+ Relief, methods of expressing. 48-51
+ Reproduction of illustrations, processes for. 72-90
+ relation of, to the drawing supplied. 7, 40
+ Reticulation, sketching by. 47
+ Retouching of photographs, materials and method used in. 68, 70-71
+ Reuse of illustrations, procedure for. 37-38
+ Rocks, igneous, names of. 95-97
+ metamorphic, names of. 95
+ sedimentary, names of. 94-95
+ symbols used to distinguish. 32
+ _See also_ Specimens.
+ Roman numerals, numbers expressed by. 93
+ Rubber, liquid, use of. 37
+
+
+ S.
+
+ Scales, bar, forms of. 50-60
+ measuring for projection of maps. 44
+ standard, of maps. 18
+ Scope of this manual. 7
+ Screens, half-tone prints showing effects produced by. 56
+ Selection of illustrations, considerations governing. 8-9
+ Sections, columnar, original drawings for. 31
+ columnar, symbols used in, plate showing. 32
+ structure, combination of, with views of topography. 30-31
+ drawing of. 64-65
+ original drawings for. 29-31
+ symbols used in, plate showing. 32
+ vertical exaggeration of. 30
+ Shading, kinds used. 67
+ Signs, mathematical, forms and names of. 04
+ Sises of illustrations. 11-12, 40
+ Specimens, borrowed and fragile, care of. 35
+ drawings of, methods of making. 60-68
+ paleontologic, transmittal of. 35
+ photographs of, how printed. 68
+ how used. 34-85
+ Springs, symbols for. 22, 23
+ State maps, use of. 15
+ Stipple, production of. 50, 51
+ Stone, engraving on. 89-90
+ Streams, drawing of. 51-52
+ lettering names of. 52
+ Submittal of illustrations. 10
+ Symbols, drawing of. 20, 61
+ for ground-water features, uniformity needed in. 21-23
+ for maps and mine plans, plates showing. 20, 46
+ uniform use of. 20, 45-46
+ for oil and gas wells, features of. 21
+ for structure and columnar sections, plate showing. 32
+ lithologic, use of. 32
+
+
+ T.
+
+ Three-color half-tones, process of making. 78-80
+ Titles of illustrations, arrangement and place of. 58
+ printing of. 19-20
+ wording and lettering of. 19
+ Tooling on half-tones, effects obtained by. 77, 78
+ Topographic atlas sheets, scales of. 14
+ Tracing, method of. 46-47
+ use of colors in. 46-47
+ Tracing linen, use of. 24-25
+ Transferring, celluloid, process of. 47
+ celluloid, requisitions for. 47
+ Type, lettering with. 54-55
+ styles and sizes of. 55
+
+
+ V.
+
+ Value of illustrations in Survey reports. 8
+ Vara, length of. 92
+ Vignetting, effect obtained by. 78
+
+
+ W.
+
+ Wall map of the United States, use of, for basemaps. 14
+ Water colors, use of. 26, 67, 71
+ Waterlining, use of. 52
+ Wax engraving, process and advantages of. 80-81
+ Wells, symbols for. 22, 23
+ Wood engraving, process of. 81-82
+
+
+ Z.
+
+ Zinc etchings, changes in. 38-39
+ drawings for. 74
+ insertion of. 11
+ making and advantages of. 73-75
+
+
+[Illustration: circle]
+
+
+ * * * * *
+
+
+Transcriber's Note
+
+Paragraphs split by illustrations were rejoined. Where Greek
+characters occurred in the original, [Greek: ] was substituted for
+them. To see these characters, view the UTF-8 or HTML version.
+
+
+
+
+
+
+End of the Project Gutenberg EBook of The Preparation of Illustrations for
+Reports of the United States Geological Survey, by John L. Ridgway
+
+*** END OF THE PROJECT GUTENBERG EBOOK 43232 ***
generated by cgit v1.2.3 (git 2.25.1) at 2025-12-23 13:12:25 +0000