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+The Project Gutenberg EBook of The Preparation of Illustrations for
+Reports of the United States Geological Survey, by John L. Ridgway
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org/license
+
+
+Title: The Preparation of Illustrations for Reports of the United States Geological Survey
+       With Brief Descriptions of Processes of Reproduction
+
+Author: John L. Ridgway
+
+Release Date: July 16, 2013 [EBook #43232]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE PREPARATION OF ILLUSTRATIONS ***
+
+
+
+
+Produced by Tom Cosmas from materials scanned in and
+obtained from The Internet Archive.
+
+
+
+
+
+
+
+
+
+
+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.
+  �kerite.                           Elvan.
+  Alaskite.                          Enstatite.
+  Albitlte.                          Eruptive rock.
+  Allivalite.                        Essexite.
+  Allochetite.                       Estrellite.
+  Aln�lte.                           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.                        Ha�ynophyre.
+  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.
+  Krager�ite.                        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.                         S�lvsbergite.
+  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.
+  Orn�ite.                           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
+
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+The Project Gutenberg EBook of The Preparation of Illustrations for
+Reports of the United States Geologi, by John L. Ridgway
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org/license
+
+
+Title: The Preparation of Illustrations for Reports of the United States Geological Survey
+       With Brief Descriptions of Processes of Reproduction
+
+Author: John L. Ridgway
+
+Release Date: July 16, 2013 [EBook #43232]
+
+Language: English
+
+Character set encoding: UTF-8
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE PREPARATION OF ILLUSTRATIONS ***
+
+
+
+
+Produced by Tom Cosmas from materials scanned in and
+obtained from The Internet Archive.
+
+
+
+
+
+
+</pre>
+
+
+<div class="fig_center" style="width: 301px;">
+<img src="images/cover.jpg" width="301" height="505" alt="cover" />
+</div>
+
+<hr class="chap" />
+
+<p><span class="pagenum"><a name="Page_1" id="Page_1">[1]</a></span></p>
+
+
+<p class="caption3">DEPARTMENT OF THE INTERIOR.</p>
+
+<p class="caption4"><span class="smcap">John Barton Payne</span>, Secretary</p>
+
+<hr class="r10" />
+
+<p class="caption3 smcap">United States Geological Survey</p>
+
+<p class="caption4"><span class="smcap">George Otis Smith</span>, Director</p>
+
+<hr class="r10" />
+
+
+<p class="caption3" style="padding-top:3em">THE</p>
+
+<p class="caption1">PREPARATION OF ILLUSTRATIONS</p>
+
+<p class="caption4">FOR REPORTS OF THE</p>
+
+<p class="caption2">UNITED STATES GEOLOGICAL SURVEY</p>
+
+<p class="caption3">WITH BRIEF DESCRIPTIONS OF PROCESSES<br />
+OF REPRODUCTION</p>
+
+
+
+<p class="pmt4 p0 center">BY</p>
+
+
+
+<p class="pmb2 caption2">JOHN L. RIDGWAY</p>
+
+
+<div class="fig_center" style="width: 129px; padding-bottom:2em;">
+<img src="images/title_doi_logo.png" width="129" height="125" alt="U.S. Geol. Surv." />
+</div>
+
+
+<p class="caption3">WASHINGTON</p>
+
+<p class="pmb4 p0 center">GOVERNMENT PRINTING OFFICE<br />
+<br />
+1920</p>
+
+<p><span class="pagenum"><a name="Page_2" id="Page_2">[2]</a></span></p>
+
+
+<div class="center">
+<table summary="title box">
+<tr>
+  <td class="bdt2 bdr bdb2 bdl pad2">THE PREPARATION OF ILLUSTRATIONS<br />
+    <br />
+    FOR REPORTS OF THE<br />
+    <br />
+    UNITED STATES GEOLOGICAL SURVEY<br />
+    <br />
+    <br />
+    BY<br />
+    <br />
+    <br />
+    JOHN L. RIDGWAY</td>
+</tr>
+</table>
+</div>
+
+<p><span class="pagenum"><a name="Page_3" id="Page_3">[3]</a></span></p>
+
+
+<p class="caption2"><a name="CONTENTS" id="CONTENTS"></a>CONTENTS.</p>
+
+
+<table width="80%" summary="ToC">
+<tr>
+  <td></td>
+  <td class="tdr">Page.</td>
+</tr>
+<tr>
+  <td>Part I. Preparation by Authors.</td>
+  <td></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Introduction</span></td>
+  <td class="tdr"><a href="#INTRODUCTION">7</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Purpose</span> and value of illustrations</td>
+  <td class="tdr"><a href="#PURPOSE_AND_VALUE">8</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Selection</span> and approval of illustrations</td>
+  <td class="tdr"><a href="#SELECTION_AND_APPROVAL">8</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Submittal</span> of illustrations</td>
+  <td class="tdr"><a href="#Page_10">10</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Kinds</span> of illustrations</td>
+  <td class="tdr"><a href="#Page_10">10</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Sizes</span> of illustrations</td>
+  <td class="tdr"><a href="#Page_11">11</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Subdivisions</span> of plates and figures</td>
+  <td class="tdr"><a href="#Page_12">12</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Preparation</span> of copy by authors</td>
+  <td class="tdr"><a href="#Page_12">12</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Character</span> of original material</td>
+  <td class="tdr"><a href="#Page_12">12</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Preliminary</span> preparation of maps</td>
+  <td class="tdr"><a href="#Page_13">13</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Material</span> available for base maps</td>
+  <td class="tdr"><a href="#Page_14">14</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Basic</span> features of maps</td>
+  <td class="tdr"><a href="#Page_17">17</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Standard</span> scales</td>
+  <td class="tdr"><a href="#Page_18">18</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Orientation</span> of maps</td>
+  <td class="tdr"><a href="#Page_18">18</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Projection</span></td>
+  <td class="tdr"><a href="#Page_18">18</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Explanation</span></td>
+  <td class="tdr"><a href="#Page_19">19</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Titles</span> of maps and other illustrations</td>
+  <td class="tdr"><a href="#Page_19">19</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Symbols</span> used on maps</td>
+  <td class="tdr"><a href="#Page_20">20</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">General</span> features</td>
+  <td class="tdr"><a href="#Page_20">20</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Letter</span> symbols</td>
+  <td class="tdr"><a href="#Page_20">20</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Oil</span> and gas symbols</td>
+  <td class="tdr"><a href="#Page_21">21</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Symbols</span> for use on maps showing features of ground water</td>
+  <td class="tdr"><a href="#Page_21">21</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Black</span>-line conventions</td>
+  <td class="tdr"><a href="#Page_23">23</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Materials</span> used in preparing maps</td>
+  <td class="tdr"><a href="#Page_23">23</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Paper</span></td>
+  <td class="tdr"><a href="#Page_23">23</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Bristol</span> board</td>
+  <td class="tdr"><a href="#Page_24">24</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Tracing</span> linen</td>
+  <td class="tdr"><a href="#Page_24">24</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Inks</span></td>
+  <td class="tdr"><a href="#Page_25">25</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Drawing</span> pens</td>
+  <td class="tdr"><a href="#Page_25">25</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Pencils</span></td>
+  <td class="tdr"><a href="#Page_25">25</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Rubber</span> erasers and cleaners</td>
+  <td class="tdr"><a href="#Page_25">25</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Colored</span> pencils and crayons</td>
+  <td class="tdr"><a href="#Page_26">26</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Water</span> colors</td>
+  <td class="tdr"><a href="#Page_26">26</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Japanese</span> transparent water colors</td>
+  <td class="tdr"><a href="#Page_26">26</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Coloring</span> geologic maps</td>
+  <td class="tdr"><a href="#Page_27">27</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Diagrams</span></td>
+  <td class="tdr"><a href="#Page_28">28</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Essential</span> features</td>
+  <td class="tdr"><a href="#Page_28">28</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Plans</span> of mine workings</td>
+  <td class="tdr"><a href="#Page_29">29</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Sections</span></td>
+  <td class="tdr"><a href="#Page_29">29</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Lithologic</span> symbols</td>
+  <td class="tdr"><a href="#Page_32">32</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Use</span> of photographs as illustrations</td>
+  <td class="tdr"><a href="#Page_32">32</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Essential</span> features</td>
+  <td class="tdr"><a href="#Page_32">32</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Copyrighted</span> photographs</td>
+  <td class="tdr"><a href="#Page_33">33</a>
+    <span class="pagenum"><a name="Page_4" id="Page_4">[4]</a></span></td>
+</tr>
+<tr>
+  <td><span class="ind3">Sources</span> of photographs</td>
+  <td class="tdr"><a href="#Page_34">34</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Lending</span> original photographs and drawings</td>
+  <td class="tdr"><a href="#Page_34">34</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Unpublished</span> photographs</td>
+  <td class="tdr"><a href="#Page_34">34</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Specimens</span></td>
+  <td class="tdr"><a href="#Page_34">34</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">General</span> requirements</td>
+  <td class="tdr"><a href="#Page_34">34</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Borrowed</span> and fragile specimens</td>
+  <td class="tdr"><a href="#Page_35">35</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Transmittal</span> of paleontologic specimens</td>
+  <td class="tdr"><a href="#Page_35">35</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Making</span> up plates</td>
+  <td class="tdr"><a href="#Page_36">36</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Reuse</span> of illustrations</td>
+  <td class="tdr"><a href="#Page_37">37</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Approval</span> of finished illustrations</td>
+  <td class="tdr"><a href="#Page_38">38</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Revision</span> of illustrations</td>
+  <td class="tdr"><a href="#Page_38">38</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Submittal</span> of proofs</td>
+  <td class="tdr"><a href="#Page_38">38</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Proof</span>-reading illustrations</td>
+  <td class="tdr"><a href="#Page_39">39</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">General</span> considerations</td>
+  <td class="tdr"><a href="#Page_39">39</a></td>
+</tr>
+<tr>
+  <td>&nbsp;</td><td></td>
+</tr>
+<tr>
+  <td>Part II. Preparation by Draftsmen.</td>
+  <td></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">General</span> directions</td>
+  <td class="tdr"><a href="#GENERAL_DIRECTIONS">41</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Instruments</span></td>
+  <td class="tdr"><a href="#Page_42">42</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Classification</span> of material</td>
+  <td class="tdr"><a href="#Page_42">42</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Preparation</span> of maps</td>
+  <td class="tdr"><a href="#Page_43">43</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Projection</span></td>
+  <td class="tdr"><a href="#Page_43">43</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Details</span> of base maps</td>
+  <td class="tdr"><a href="#Page_45">45</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Transferring</span> or copying</td>
+  <td class="tdr"><a href="#Page_46">46</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Tracing</span></td>
+  <td class="tdr"><a href="#Page_46">46</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Celluloid</span> transferring</td>
+  <td class="tdr"><a href="#Page_47">47</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Sketching</span> by reticulation</td>
+  <td class="tdr"><a href="#Page_47">47</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">The</span> "shadowless drafting table"</td>
+  <td class="tdr"><a href="#Page_47">47</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Topographic</span> features</td>
+  <td class="tdr"><a href="#Page_48">48</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Relief</span></td>
+  <td class="tdr"><a href="#Page_48">48</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Hydrography</span></td>
+  <td class="tdr"><a href="#Page_51">51</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Cultural</span> features</td>
+  <td class="tdr"><a href="#Page_52">52</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Lettering</span></td>
+  <td class="tdr"><a href="#Page_53">53</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">General</span> directions</td>
+  <td class="tdr"><a href="#Page_53">53</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Lettering</span> by type</td>
+  <td class="tdr"><a href="#Page_54">54</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Abbreviations</span></td>
+  <td class="tdr"><a href="#Page_55">55</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Names</span> of railroads</td>
+  <td class="tdr"><a href="#Page_57">57</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Make</span>-up of maps</td>
+  <td class="tdr"><a href="#Page_57">57</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Forms</span> for certain features</td>
+  <td class="tdr"><a href="#Page_57">57</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Border</span></td>
+  <td class="tdr"><a href="#Page_57">57</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Title</span></td>
+  <td class="tdr"><a href="#Page_58">58</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Explanation</span></td>
+  <td class="tdr"><a href="#Page_58">58</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Graphic</span> scales for maps</td>
+  <td class="tdr"><a href="#Page_59">59</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Symbols</span></td>
+  <td class="tdr"><a href="#Page_61">61</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Areal</span> patterns for black and white maps</td>
+  <td class="tdr"><a href="#Page_61">61</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind3">Standard</span> colors for geologic maps</td>
+  <td class="tdr"><a href="#Page_63">63</a></td>
+</tr>
+<tr>
+  <td><span class="ind3">Reduction</span> or enlargement of maps</td>
+  <td class="tdr"><a href="#Page_63">63</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Diagrams</span></td>
+  <td class="tdr"><a href="#Page_64">64</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Sections</span></td>
+  <td class="tdr"><a href="#Page_64">64</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Plans</span> and cross sections of mines</td>
+  <td class="tdr"><a href="#Page_65">65</a>
+    <span class="pagenum"><a name="Page_5" id="Page_5">[5]</a></span></td>
+</tr>
+<tr>
+  <td><span class="ind1">Drawings</span> of specimens of rocks and fossils</td>
+  <td class="tdr"><a href="#METHODS_EMPLOYED">66</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Methods</span> used</td>
+  <td class="tdr"><a href="#Page_66">66</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Brush</span> and pencil drawings</td>
+  <td class="tdr"><a href="#Page_66">66</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Pen</span> drawings</td>
+  <td class="tdr"><a href="#Page_67">67</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Retouching</span> photographs of specimens</td>
+  <td class="tdr"><a href="#Page_68">68</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Landscape</span> drawings from poor photographs</td>
+  <td class="tdr"><a href="#Page_68">68</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Pen</span> drawings made over photographs</td>
+  <td class="tdr"><a href="#Page_68">68</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Brush</span> drawings from poor photographs</td>
+  <td class="tdr"><a href="#Page_69">69</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Outdoor</span> sketches</td>
+  <td class="tdr"><a href="#Page_69">69</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Drawings</span> of crystals</td>
+  <td class="tdr"><a href="#Page_70">70</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Retouching</span> photographs</td>
+  <td class="tdr"><a href="#Page_70">70</a></td>
+</tr>
+<tr>
+  <td>&nbsp;</td><td></td>
+</tr>
+<tr>
+  <td>Part III. Processes of Reproducing Illustrations.</td>
+  <td></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Methods</span> employed</td>
+  <td class="tdr"><a href="#Page_72">72</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Photoengraving</span></td>
+  <td class="tdr"><a href="#Page_72">72</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">General</span> features</td>
+  <td class="tdr"><a href="#Page_72">72</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Zinc</span> etching</td>
+  <td class="tdr"><a href="#Page_73">73</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Copper</span> etching in relief</td>
+  <td class="tdr"><a href="#Page_75">75</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Half</span>-tone engraving</td>
+  <td class="tdr"><a href="#Page_75">75</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Three</span>-color half-tone process</td>
+  <td class="tdr"><a href="#Page_78">78</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Wax</span> engraving (the cerotype process)</td>
+  <td class="tdr"><a href="#Page_80">80</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Wood</span> engraving</td>
+  <td class="tdr"><a href="#Page_81">81</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Photogelatin</span> processes</td>
+  <td class="tdr"><a href="#Page_82">82</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Lithography</span></td>
+  <td class="tdr"><a href="#Page_83">83</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Original</span> process</td>
+  <td class="tdr"><a href="#Page_83">83</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Photolithography</span></td>
+  <td class="tdr"><a href="#Page_86">86</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Offset</span> printing</td>
+  <td class="tdr"><a href="#Page_87">87</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind2">Chromolithography</span></td>
+  <td class="tdr"><a href="#Page_87">87</a></td>
+</tr>
+<tr>
+  <td><span class="ind2">Engraving</span> on stone and on copper</td>
+  <td class="tdr"><a href="#Page_89">89</a></td>
+</tr>
+<tr>
+  <td>&nbsp;</td><td></td>
+</tr>
+<tr>
+  <td>Appendix.</td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Length</span> of degrees of latitude and longitude</td>
+  <td class="tdr"><a href="#Page_91">91</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Metric</span> system and equivalents</td>
+  <td class="tdr"><a href="#Page_92">92</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Geologic</span> eras, periods, systems, epochs, and series</td>
+  <td class="tdr"><a href="#Page_92">92</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Chemical</span> elements and symbols</td>
+  <td class="tdr"><a href="#Page_93">93</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Greek</span> alphabet</td>
+  <td class="tdr"><a href="#Page_93">93</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Roman</span> numerals</td>
+  <td class="tdr"><a href="#Page_93">93</a></td>
+</tr>
+<tr class="row1">
+  <td><span class="ind1">Mathematical</span> signs</td>
+  <td class="tdr"><a href="#Page_94">94</a></td>
+</tr>
+<tr>
+  <td><span class="ind1">Names</span> of rocks</td>
+  <td class="tdr"><a href="#Page_94">94</a></td>
+</tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_6" id="Page_6">[6]</a></span></p>
+
+
+<p class="caption2">ILLUSTRATIONS.</p>
+
+<table style="width:80%" summary="LoI">
+<tr>
+  <td colspan="3"></td>
+  <td class="tdr">Page.</td>
+</tr>
+<tr class="row1">
+  <td class="vtop">Plate</td>
+  <td class="vtop tdr">I.</td>
+  <td>Methods of inserting plates and figures</td>
+  <td class="tdr"><a href="#Plate_I">10</a></td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">II.</td>
+  <td>Symbols used on geologic maps, economic maps,
+             and mine plans</td>
+  <td class="tdr"><a href="#Plate_II">20</a></td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">III.</td>
+  <td>Lithologic symbols used in structure and columnar
+             sections to represent different kinds of rock</td>
+  <td class="tdr"><a href="#Plate_III">32</a></td>
+</tr>
+<tr>
+  <td></td>
+  <td class="tdr">IV.</td>
+  <td>Symbols used on base maps</td>
+  <td class="tdr"><a href="#Plate_IV">52</a></td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">V.</td>
+  <td>Reduction sheet used in lettering illustrations</td>
+  <td class="tdr"><a href="#Plate_V">54</a></td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">VI.</td>
+  <td>Half-tone prints showing effects produced by the
+             use of six standard screens</td>
+  <td class="tdr"><a href="#Plate_VI">56</a></td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="tdr">VII.</td>
+  <td>Details of the make-up of a geologic map</td>
+  <td class="tdr"><a href="#Plate_VII">58</a></td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">VIII.</td>
+  <td>Patterns used to show distinctions between areas
+             on black and white maps</td>
+  <td class="tdr"><a href="#Plate_VIII">60</a></td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="tdr">IX.</td>
+  <td>Diagrams and curves</td>
+  <td class="tdr"><a href="#Plate_IX">64</a></td>
+</tr>
+<tr>
+  <td colspan="4">&nbsp;</td>
+</tr>
+<tr class="row1">
+  <td class="vtop">Figure</td>
+  <td class="vtop tdr">1.</td>
+  <td>Diagrams showing principal, guide, and auxiliary
+             meridians, standard and special parallels and
+             correction lines, and system of numbering
+             townships, ranges, and sections</td>
+  <td class="tdr">16</td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">2.</td>
+  <td>Conventional lines used in preparing plans and
+             diagrams of mine workings to distinguish
+             different levels</td>
+  <td class="tdr">29</td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">3.</td>
+  <td>Section and perspective view showing relations
+             of surface features to the different kinds of
+             rocks and the structure of the beds</td>
+  <td class="tdr">30</td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">4.</td>
+  <td>Sections of coal beds</td>
+  <td class="tdr">31</td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">5.</td>
+  <td>Diagram illustrating method of projecting a map</td>
+  <td class="tdr">44</td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">6.</td>
+  <td>Methods of expressing relief by contour lines,
+             by hachures, by shading on stipple board, and
+             by a brush drawing</td>
+  <td class="tdr">49</td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">7.</td>
+  <td>Designs for bar scales</td>
+  <td class="tdr">60</td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">8.</td>
+  <td>Method of making a bar scale for a map of
+             unknown scale</td>
+  <td class="tdr">60</td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">9.</td>
+  <td>Map bearing six areal line patterns</td>
+  <td class="tdr">62</td>
+</tr>
+<tr>
+  <td></td>
+  <td class="vtop tdr">10.</td>
+  <td>Diagram showing method of marking maps for
+             reduction or enlargement (for record)</td>
+  <td class="tdr">64</td>
+</tr>
+<tr class="row1">
+  <td></td>
+  <td class="vtop tdr">11.</td>
+  <td>Structure section showing method of determining
+             the succession of folds</td>
+  <td class="tdr">65</td>
+</tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_7" id="Page_7">[7]</a></span></p>
+
+
+<p class="caption1">THE PREPARATION OF ILLUSTRATIONS FOR REPORTS OF
+THE United STATES GEOLOGICAL SURVEY.</p>
+
+
+<p class="caption2">By John L. Ridgway.</p>
+
+
+
+
+<p class="caption2"><a name="PART_I" id="PART_I"></a>
+<span class="smcap">Part I. Preparation By Authors.</span></p>
+
+
+
+
+<p class="caption2"><a name="INTRODUCTION" id="INTRODUCTION"></a>
+INTRODUCTION.</p>
+
+
+<p>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.</p>
+
+<p>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&mdash;first the preparation of the author's original or rough
+draft, next the final drawing, and last the reproduction&mdash;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.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_8" id="Page_8">[8]</a></span></p>
+
+
+
+
+<p class="caption2"><a name="PURPOSE_AND_VALUE" id="PURPOSE_AND_VALUE"></a>
+PURPOSE AND VALUE OF ILLUSTRATIONS.</p>
+
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="SELECTION_AND_APPROVAL" id="SELECTION_AND_APPROVAL"></a>
+SELECTION AND APPROVAL OF ILLUSTRATIONS.</p>
+
+
+<p>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
+<span class="pagenum"><a name="Page_9" id="Page_9">[9]</a></span>
+not decisive. The tendency to overillustrate led the Director to issue
+the following order<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a> governing the approval of illustrations:</p>
+
+<div class="footnote"><p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> From Survey Order 63, Oct. 20, 1915.</p></div>
+
+<div class="blockquot"><p>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.</p>
+
+<p>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.</p></div>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_10" id="Page_10">[10]</a></span></p>
+
+
+
+
+<p class="caption2">SUBMITTAL OF ILLUSTRATIONS.</p>
+
+
+<p>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 &mdash;&mdash; by &mdash;&mdash;." 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."</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="KINDS_OF_ILLUSTRATIONS" id="KINDS_OF_ILLUSTRATIONS"></a>KINDS OF ILLUSTRATIONS.</p>
+
+
+<p>The illustrations in reports of the Geological Survey may be classified
+into five more or less distinct groups&mdash;(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.</p>
+
+<div style="width:100%; margin-top:1em;"><a name="Plate_I" id="Plate_I"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE I</div>
+<div class="fig_center" style="width:641px;">
+<img src="images/plate_i_a.png" width="641" height="523" style="position:relative; top:4px;" alt="" />
+<img src="images/plate_i_b.png" width="641" height="569" alt="" /><br />
+<p class="captionbm">METHODS OF INSERTING PLATES AND FIGURES.<br />
+1, 2, 3, 5, 6, 7, plates; 4, 8, 9, 10, figures; 11, pocket.</p>
+</div>
+</div>
+
+<p><span class="pagenum"><a name="Page_11" id="Page_11">[11]</a></span></p>
+
+<p>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 <a href="#Plate_VI">Plate VI</a>
+(<a href="#Plate_VI">p. 56</a>), however, a
+half-tone cut may be made that can be used in the text if it is smaller
+than the page.</p>
+
+
+
+
+<p class="caption2"><a name="SIZES_OF_ILLUSTRATIONS" id="SIZES_OF_ILLUSTRATIONS"></a>SIZES OF ILLUSTRATIONS.</p>
+
+
+<p>The regular book publications of the Geological Survey are issued
+in three sizes&mdash;(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:</p>
+
+<table summary="sizes">
+<tr>
+  <td style="width:20%"></td>
+  <td style="width:35%" colspan="5" class="center">Size of text.</td>
+  <td style="width:10%">&nbsp;&nbsp;</td>
+  <td style="width:35%" colspan="5" class="center">Size of page.</td>
+</tr>
+<tr>
+  <td>Octavo</td>
+  <td class="tdr">4</td><td><sup>3</sup>/<sub>8</sub></td><td>by</td><td class="tdr">7</td><td><sup>15</sup>/<sub>16</sub></td>
+  <td></td>
+  <td class="tdr">5</td><td><sup>7</sup>/<sub>8</sub></td><td>by</td><td class="tdr">9</td><td><sup>1</sup>/<sub>8</sub></td>
+</tr>
+<tr>
+  <td>Quarto</td>
+  <td class="tdr">6</td><td><sup>1</sup>/<sub>16</sub></td><td>by</td><td class="tdr">9</td><td><sup>1</sup>/<sub>8</sub></td>
+  <td></td>
+  <td class="tdr">9</td><td><sup>1</sup>/<sub>4</sub></td><td>by</td><td class="tdr">11</td><td><sup>5</sup>/<sub>8</sub></td>
+</tr>
+<tr>
+  <td>Folio</td>
+  <td class="tdr">13</td><td><sup>13</sup>/<sub>16</sub></td><td>by</td><td class="tdr">17</td><td><sup>7</sup>/<sub>8</sub></td>
+  <td></td>
+  <td class="tdr">18</td><td><sup>1</sup>/<sub>2</sub></td><td>by</td><td class="tdr">21</td><td><sup>3</sup>/<sub>4</sub></td>
+</tr>
+</table>
+
+<p>Most professional papers are printed in two columns of type, each
+3 inches wide, and folios are printed in three columns, each 4<sup>3</sup>/<sub>8</sub> 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.</p>
+
+<p>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 <a href="#Plate_I">Pl. I</a>.)</p>
+
+<table summary="Size Limits">
+<tr>
+  <td style="width:10%;"></td>
+  <td style="width:30%;" class="center" colspan="5">Single-page plate.</td>
+  <td style="width:30%;" class="center" colspan="5">Plate with one side fold.</td>
+  <td style="width:30%;" class="center" colspan="5">Text figure.</td>
+</tr>
+<tr>
+  <td>Octavo</td>
+  <td class="tdr">4</td><td><sup>3</sup>/<sub>8</sub></td><td>by</td><td class="tdr">7</td><td><sup>1</sup>/<sub>2</sub></td>
+  <td class="tdr">7</td><td><sup>1</sup>/<sub>2</sub></td><td>by</td><td class="tdr">8</td><td><sup>1</sup>/<sub>2</sub></td>
+  <td class="center">4 <sup>3</sup>/<sub>8</sub></td><td>by</td><td class="tdr">7</td><td><sup>1</sup>/<sub>2</sub></td>
+</tr>
+<tr>
+  <td>Quarto</td>
+  <td class="tdr">6</td><td></td><td>by</td><td class="tdr">9</td><td></td>
+  <td class="tdr">9</td><td><sup>1</sup>/<sub>2</sub></td><td>by</td><td class="tdr">14</td><td><sup>3</sup>/<sub>4</sub></td>
+  <td class="center">3 or 6</td><td>by</td><td class="tdr">8</td><td><sup>1</sup>/<sub>2</sub></td>
+</tr>
+<tr>
+  <td>Folio</td>
+  <td class="tdr">15</td><td></td><td>by</td><td class="tdr">17</td><td><sup>1</sup>/<sub>2</sub></td>
+  <td class="center" colspan="5" style="letter-spacing:0.25em">............</td>
+  <td>4<sup>3</sup>/<sub>8</sub> or 13<sup>13</sup>/<sub>16</sub></td><td>by</td><td class="tdr">17</td><td><sup>7</sup>/<sub>8</sub></td>
+</tr>
+</table>
+
+<p>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
+<span class="pagenum"><a name="Page_12" id="Page_12">[12]</a></span>
+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.</p>
+
+<p>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 <a href="#Plate_I">Plate I</a>, figures 4, 8, 9, 10.</p>
+
+
+
+
+<p class="caption2">SUBDIVISIONS OF PLATES AND FIGURES.</p>
+
+
+<p>If a plate consists of two or more parts or photographs each part
+should be marked with an italic capital letter&mdash;<b>A</b>, <b>B</b>, etc.&mdash;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&mdash;1, 2, 3, etc.
+If a text figure is subdivided into two or more parts, each part should
+be marked with a roman capital&mdash;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&mdash;a, 6, c, etc.</p>
+
+
+
+
+<p class="caption2"><a name="PREPARATION_OF_COPY_BY_AUTHORS" id="PREPARATION_OF_COPY_BY_AUTHORS"></a>PREPARATION OF COPY BY AUTHORS.</p>
+
+
+<p class="caption3">CHARACTER OF ORIGINAL MATERIAL.</p>
+
+<p>In the Geological Survey, as elsewhere, the "originals"&mdash;that is,
+the original material submitted by authors for the illustration of
+their reports&mdash;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
+<span class="pagenum"><a name="Page_13" id="Page_13">[13]</a></span>
+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&deg; from true north," "add," "cut out."</p>
+
+
+<p class="caption3">PRELIMINARY PREPARATION OF MAPS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.
+<span class="pagenum"><a name="Page_14" id="Page_14">[14]</a></span>
+If, however, no draftsmen are available in that division or branch, an
+arrangement can be made with any other branch&mdash;as the topographic
+or publication branch&mdash;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.</p>
+
+
+<p class="caption3">MATERIAL AVAILABLE FOR BASE MAPS.</p>
+
+<p>The maps already published by the Geological Survey<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">[2]</a> 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:</p>
+
+<p>1. The Survey's regular topographic atlas sheets, published on three
+scales&mdash;15-minute sheets, scale, 1:62,500; 30-minute sheets, scale,
+1:125,000; 60-minute sheets, scale, 1:250,000&mdash;approximately 1 mile,
+2 miles, and 4 miles to 1 inch, respectively&mdash;and its "special" maps,<a href="#Footnote_2_2" class="fnanchor">[2]</a>
+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.</p>
+
+<p>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&deg; of longitude and 4&deg; 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.</p>
+
+<p>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).</p>
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_15" id="Page_15">[15]</a></span>
+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 <a href="#Figure_1">fig. 1</a>.)</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>8. The Survey's three small base maps of the United States&mdash;(<i>a</i>)
+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;
+(<i>b</i>) a map 11 by 16 inches, scale 190 miles to 1 inch; (<i>c</i>) a map
+7<sup>1</sup>/<sub>2</sub> 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.</p>
+
+<p>9. The Century, Rand McNally &amp; Co.'s, Cram's, Stieler's, The
+Times, Johnston's Royal, and county atlases.</p>
+
+<p>10. State and county maps.</p>
+
+<p>11. Railroad surveys, which are useful in furnishing data for elevations
+as well as for locations of towns and stations.</p>
+
+<p>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.</p>
+
+<div class="footnote"><p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">[2]</span></a> See "Topographic maps and folios and geologic folios published by the United States
+Geological Survey" (latest edition).</p>
+
+<p><span class="pagenum"><a name="Page_16" id="Page_16">[16]</a></span></p></div>
+
+<div class="fig_center" style="width: 392px;">
+<a name="Figure_1" id="Figure_1"></a>
+<a href="images/figure01_lrg.png"><img src="images/figure01.png" width="392" height="612" alt="" /></a>
+<span class="caption">Figure 1.&mdash;Diagrams showing principal, guide, and auxiliary meridians, standard and
+special parallels and correction lines, and system of numbering townships, ranges,
+and sections.</span>
+</div>
+
+<p><span class="pagenum"><a name="Page_17" id="Page_17">[17]</a></span></p>
+
+<p>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.</p>
+
+
+<p class="caption3">BASIC FEATURES OF MAPS.</p>
+
+<p>It must be remembered that "every map, whatever its scale, is a
+reduction from nature and consequently must be more or less generalized."<a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">[3]</a>
+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.</p>
+
+<div class="footnote"><p><a name="Footnote_3_3" id="Footnote_3_3"></a>
+<a href="#FNanchor_3_3"><span class="label">[3]</span></a> Gannett,
+Henry, A manual of topographic methods: U. S. Geol. Survey Mon. 22, p.
+107, 1893.</p></div>
+
+<p>If the three fundamental features of a topographic map&mdash;the culture,
+the drainage, and the relief&mdash;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 "<a href="#INKS">Inks</a>," <a href="#INKS">p. 25</a>.) The photographer will then make three
+<span class="pagenum"><a name="Page_18" id="Page_18">[18]</a></span>
+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.</p>
+
+
+<p class="caption3">STANDARD SCALES.</p>
+
+<p>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 <a href="#Page_47">p. 47</a>.)</p>
+
+<p>Maps compiled by an author should be prepared on a scale of at
+least 1<sup>1</sup>/<sub>2</sub> 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.</p>
+
+
+<p class="caption3">ORIENTATION OF MAPS.</p>
+
+<p>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 Pls. X and XII, Bull. 628; and Pls. VI, XV, and XVI,
+Mon. 52.)</p>
+
+
+<p class="caption3">PROJECTION.<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">[4]</a></p>
+
+<div class="footnote"><p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">[4]</span></a> See also pp. 43-45, where the method of projecting a map is more fully explained.</p></div>
+
+<p>The polyconic projection has been adopted by the Geological Survey
+for its topographic atlas sheets and must be consistently used
+<span class="pagenum"><a name="Page_19" id="Page_19">[19]</a></span>
+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.<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">[5]</a></p>
+
+<div class="footnote"><p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">[5]</span></a> See pp. 49-48 for methods of tracing and transferring.</p></div>
+
+
+<p class="caption3">EXPLANATION.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Each original map submitted by an author should have at least
+4<sup>1</sup>/<sub>2</sub> 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.</p>
+
+
+<p class="caption3">TITLES OF MAPS AND OTHER ILLUSTRATIONS.</p>
+
+<p>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 <a href="#Page_58">p. 58</a>.) 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 repro
+<span class="pagenum"><a name="Page_20" id="Page_20">[20]</a></span>duced
+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.</p>
+
+
+<p class="caption3">SYMBOLS USED ON MAPS.</p>
+
+<p class="caption4">GENERAL FEATURES.</p>
+
+<p>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
+<a href="#Plate_II">Plate II</a> 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.</p>
+
+<p>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.</p>
+
+<p class="caption4">LETTER SYMBOLS.</p>
+
+<p>The letter symbols used on most geologic maps to indicate the
+ages and names of the formations represented consist of two or more
+letters&mdash;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&mdash;lower terrace deposits); Cpv (Carboniferous&mdash;Pottsville
+formation); COk (Cambrian-Ordovician&mdash;Knox
+dolomite), etc. The standard usage for this feature is shown
+in the geologic folios but is subject to modification in other publications.</p>
+
+<p>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.</p>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_II" id="Plate_II"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE II</div>
+
+<img src="images/plate_ii_a.png" width="633" height="610" style="position:relative; top:4px;" alt="" />
+<img src="images/plate_ii_b.png" width="633" height="529" alt="" />
+
+<p class="captionbm">SYMBOLS USED ON GEOLOGIC MAPS, ECONOMIC MAPS AND MINE PLANS</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_21" id="Page_21">[21]</a></span></p>
+
+<p class="caption4">OIL AND GAS SYMBOLS.</p>
+
+<p>A complete set of symbols for maps showing oil and gas is given
+on <a href="#Plate_II">Plate II</a>. Referring to these symbols the chief geologist, in a
+memorandum to the Director, writes:</p>
+
+<div class="blockquot">
+<p>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.</p>
+
+<p>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.</p>
+
+<p>The symbols here submitted [see <a href="#Plate_II">PI. II</a>] 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.</p>
+
+<p>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.</p>
+</div>
+
+<p class="caption4">SYMBOLS FOR USE ON MAPS SHOWING FEATURES OF GROUND WATER.</p>
+
+<p>The symbols used on maps relating to ground water represent the
+features named below, each of which has been shown in publications
+already issued.</p>
+
+<table style="width:35em;" summary="Map Symbols">
+<tr>
+  <td>Area of absorption or outcrop.<br />
+  Depth to water table.<br />
+  Contours of water table.<br />
+  Fluctuation of water table.<br />
+  Depth to water-bearing formation.<br />
+  Structure contours of water-bearing<br />
+  &nbsp;&nbsp;&nbsp;formation.<br />
+  Area of artesian flow.<br />
+  Head of artesian water.</td>
+  <td class="vtop">Area that discharges ground water.<br />
+  Quality of ground water.<br />
+  Area irrigated with ground water.<br />
+  Nonflowing well.<br />
+  Flowing well.<br />
+  Unsuccessful or dry well.<br />
+  Well with pumping plant.<br />
+  Spring.</td>
+</tr>
+</table>
+
+<p>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
+<span class="pagenum"><a name="Page_22" id="Page_22">[22]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="caption3"><i>General ground-water features.</i></p>
+
+<div class="blockquot">
+<p>Area of absorption or outcrop: Flat color used on the map to show the geologic
+system in which the absorbing formation occurs.</p>
+
+<p>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.</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_23" id="Page_23">[23]</a></span></p>
+
+<div class="blockquot">
+<p>Contours of water table, or contours on water-bearing formations: Gray or
+purple curves or lines.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Head of artesian water: Blue curves or lines.</p>
+
+<p>Areas that discharge ground water: Blue flat tint, or fine ruling in blue.</p>
+
+<p>Areas irrigated with ground water: Green flat tint, or fine ruling in green.</p>
+</div>
+
+<div class="fig_left" style="width: 31px; padding-left: 10%">
+<img src="images/page23.png" width="31" height="159" alt="" title="" />
+</div>
+<p class="p0"><br />
+Well, character not indicated.<br />
+Well, nonflowing.<br />
+Well, flowing.<br />
+Well, unsuccessful or dry.<br />
+Well, nonflowing, with pumping plant.<br />
+Well, flowing, with pumping plant.<br />
+Springs.<br />
+Spring, thermal.<br />
+Spring, mineral.<br />
+</p>
+
+<p style="clear:both">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.</p>
+
+
+<p class="caption3">BLACK-LINE CONVENTIONS.</p>
+
+<p>A complete set of the black-line patterns used to distinguish areas
+on a map is given in <a href="#Plate_VIII">Plate VIII</a> (<a href="#Page_60">p. 60</a>), and their application to
+a finished drawing is shown in <a href="#Figure_9">figure 9</a> (<a href="#Page_62">p. 62</a>). 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.</p>
+
+
+<p class="caption3">MATERIALS USED IN PREPARING MAPS.</p>
+
+<p class="caption4">PAPER.</p>
+
+<p>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.</p>
+
+<p>The following brands of paper are used in the Survey in the
+preparation of maps:</p>
+
+<p>"Normal" K. &amp; E., unmounted. Has an excellent surface and
+comes in flat sheets, 19 by 24, 22 by 30, and 27 by 40 inches.</p>
+
+<p><span class="pagenum"><a name="Page_24" id="Page_24">[24]</a></span></p>
+
+<p>"Paragon" K. &amp; E., mounted on muslin. In 10-yard rolls 72
+inches wide. Used in the Survey for large office drawings and maps
+of large scale.</p>
+
+<p>"Anvil" K. &amp; E., mounted on muslin. In 10-yard rolls 42, 62,
+and 72 inches wide. Used in the Survey for large drawings.</p>
+
+<p>"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.</p>
+
+<p>"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 <a href="#Page_51">p. 51</a> for method of using.)</p>
+
+<p>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.</p>
+
+<p class="caption4">BRISTOL BOARD.</p>
+
+<p>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<sup>1</sup>/<sub>2</sub> by 20<sup>3</sup>/<sub>4</sub>, 18<sup>1</sup>/<sub>4</sub> by 22<sup>3</sup>/<sub>8</sub>, and
+21<sup>1</sup>/<sub>2</sub> by 28<sup>3</sup>/<sub>4</sub> inches.</p>
+
+<p class="caption4">TRACING LINEN.</p>
+
+<p>Tracing cloth or linen is especially useful for large work that will
+require considerable reduction. (See <a href="#Page_18">p. 18</a>.) 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
+<span class="pagenum"><a name="Page_25" id="Page_25">[25]</a></span>
+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.</p>
+
+<p>Erasures should be made on tracing linen with a hard rubber
+eraser, not with a sand rubber or a steel eraser.</p>
+
+<p class="caption4"><a name="INKS" id="INKS"></a>INKS.</p>
+
+<p>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 &amp; 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 &amp; Newton's water color
+of that name.</p>
+
+<p>Ink lines should be drawn in full strength of color&mdash;lines that
+should be black must not appear grayish, for example&mdash;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.</p>
+
+<p class="caption4">DRAWING PENS.</p>
+
+<p>The pens made by Keuffel &amp; 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.</p>
+
+<p class="caption4">PENCILS.</p>
+
+<p>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.</p>
+
+<p class="caption4">RUBBER ERASERS AND CLEANERS.</p>
+
+<p>Two kinds of rubber erasers are usually employed in making
+erasures on drawings&mdash;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.</p>
+
+<p><span class="pagenum"><a name="Page_26" id="Page_26">[26]</a></span></p>
+
+<p class="caption4">COLORED PENCILS AND CRAYONS.</p>
+
+<p>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.</p>
+
+<p class="caption4">WATER COLORS.</p>
+
+<p>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.</p>
+
+<table style="width:35em;" summary="Water colors">
+<tr>
+  <td>Mauve.<br />
+  Crimson lake.<br />
+  Orange-vermilion.<br />
+  Burnt sienna.<br />
+  Cadmium-yellow.<br />
+  Chrome-yellow.<br />
+  Olive-green.</td>
+  <td class="vtop">Hooker's green No. 2.<br />
+  Emerald-green.<br />
+  Payne's gray.<br />
+  Lampblack.<br />
+  Sepia.<br />
+  Cerulean blue.</td>
+</tr>
+</table>
+
+<p>Other pigments spread better than cerulean blue and emerald-green,
+but the exceptional purity of color of these two seems to warrant
+their use.</p>
+
+<p class="caption4">JAPANESE TRANSPARENT WATER COLORS.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_27" id="Page_27">[27]</a></span></p>
+
+<p class="caption3">COLORING GEOLOGIC MAPS.</p>
+
+<p>The colors used on most original maps are not pleasing, a fact that
+is of no particular importance, but&mdash;and this is of importance&mdash;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 <a href="#Page_26">page 26</a> will
+give 24 satisfactory distinctions and will thus supply all demands for
+map coloring.</p>
+
+<p>To insure satisfactory contrasts between colored areas on a map,
+unlike colors should be placed next to each other&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>The Survey's color scheme (see <a href="#Page_63">p. 63</a>) need not be applied at this
+stage of preparation, except in the most general way. Appropriate
+<span class="pagenum"><a name="Page_28" id="Page_28">[28]</a></span>
+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.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">DIAGRAMS.</p>
+
+<p class="caption4">ESSENTIAL FEATURES.</p>
+
+<p>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"&mdash;the relief&mdash;in such drawings is not easily
+expressed and should be brought out clearly in the author's rough
+sketches.</p>
+
+<p><span class="pagenum"><a name="Page_29" id="Page_29">[29]</a></span></p>
+
+<p>For illustrations of apparatus photographs are preferred, but
+if rough sketches are submitted they should show not only correct
+relations but all dimensions.</p>
+
+<p class="caption4">PLANS OF MINE WORKINGS.</p>
+
+<p>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.</p>
+
+<div class="fig_center" style="width: 661px;">
+<a name="Figure_2" id="Figure_2"></a>
+<img src="images/figure02_lrg.png" width="661" height="356" alt="" />
+<span class="caption">Figure 2.&mdash;Conventional lines used in preparing plans and diagrams of mine workings to
+distinguish different levels.</span>
+</div>
+
+<p>The levels in plans of underground workings can be differentiated
+in finished drawings by a system of conventional outlines in black,
+as shown in <a href="#Figure_2">figure 2</a>, 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.</p>
+
+<p class="caption4">SECTIONS.</p>
+
+<p>The standard forms of geologic sections are shown in the geologic
+folios. Structure sections should be prepared with great care as to
+<span class="pagenum"><a name="Page_30" id="Page_30">[30]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<div class="fig_center" style="width: 734px;">
+<a name="Figure_3" id="Figure_3"></a>
+<img src="images/figure03_lrg.png" width="734" height="189" alt="" />
+<span class="caption">Figure 3.&mdash;Section and perspective view showing relations of surface features to the
+different kinds of rock and the structure of the beds.</span>
+</div>
+
+<p>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.
+<span class="pagenum"><a name="Page_31" id="Page_31">[31]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<div class="fig_center" style="width: 745px;">
+<a name="Figure_4" id="Figure_4"></a>
+<img src="images/figure04_lrg.png" width="745" height="390" alt="" />
+<span class="caption">Figure 4.&mdash;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.</span>
+</div>
+
+<p>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 <a href="#Figure_4">figure 4</a>. 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 <a href="#Figure_4">figure 4</a>. 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.</p>
+
+<p><span class="pagenum"><a name="Page_32" id="Page_32">[32]</a></span></p>
+
+<p class="caption3">LITHOLOGIC SYMBOLS.</p>
+
+<p>The symbols used to indicate the various kinds of rocks illustrated
+in sections and diagrams are shown in <a href="#Plate_III">Plate III</a>. The units or elements
+of these symbols may be spaced more openly in generalized
+diagrammatic sections than in sections that show great detail.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">USE OF PHOTOGRAPHS AS ILLUSTRATIONS.</p>
+
+<p class="caption4">ESSENTIAL FEATURES.</p>
+
+<p>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&mdash;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.</p>
+
+<p>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&mdash;brush
+marks, etc.&mdash;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.</p>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_III" id="Plate_III"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS. PLATE III.</div>
+
+<a href="images/plate_iii_lrg.png"><img src="images/plate_iii.png" width="597" height="346" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+
+<p class="captionbm">LITHOLOGIC SYMBOLS USED IN STRUCTURE AND COLUMNAR
+SECTIONS TO REPRESENT DIFFERENT KINDS OF ROCK</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_33" id="Page_33">[33]</a></span></p>
+
+<p>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.</p>
+
+<p>If a print is of doubtful quality two copies of it should be submitted&mdash;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.</p>
+
+<p>With slight trimming and reduction, three photographs measuring
+3<sup>1</sup>/<sub>4</sub> by 5<sup>1</sup>/<sub>2</sub> 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.</p>
+
+<p>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."</p>
+
+<p class="caption4">COPYRIGHTED PHOTOGRAPHS.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_34" id="Page_34">[34]</a></span>
+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.</p>
+
+<p class="caption4">SOURCES OF PHOTOGRAPHS.</p>
+
+<p>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.</p>
+
+<p class="caption4">LENDING ORIGINAL PHOTOGRAPHS AND DRAWINGS.</p>
+
+<p>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.</p>
+
+<p class="caption4">UNPUBLISHED PHOTOGRAPHS.</p>
+
+<p>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.</p>
+
+<p>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)."</p>
+
+
+<p class="caption3">SPECIMENS.</p>
+
+<p class="caption4">GENERAL REQUIREMENTS.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_35" id="Page_35">[35]</a></span>
+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.</p>
+
+<p class="caption4">BORROWED AND FRAGILE SPECIMENS.</p>
+
+<p>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.</p>
+
+<p class="caption4">TRANSMITTAL OF PALEONTOLOGIC SPECIMENS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_36" id="Page_36">[36]</a></span></p>
+
+<p class="caption3">MAKING UP PLATES.</p>
+
+<p>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 <a href="#Page_11">page 11</a> will determine the size of the plate.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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 <a href="#Page_11">p. 11</a>), and each figure
+should be properly oriented&mdash;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.</p>
+
+<p><span class="pagenum"><a name="Page_37" id="Page_37">[37]</a></span></p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+<p class="caption3"><a name="REUSE_OF_ILLUSTRATIONS" id="REUSE_OF_ILLUSTRATIONS"></a>
+REUSE OF ILLUSTRATIONS.</p>
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_38" id="Page_38">[38]</a></span>
+such a cut should be referred to by its number as plate or figure and
+the volume in which it was first used.</p>
+
+<p>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<sup>1</sup>/<sub>2</sub> to 5<sup>1</sup>/<sub>2</sub> cents a square inch of printing surface.
+The minimum charge for a single electrotype ranges from 46 to 60
+cents.</p>
+
+
+<p class="caption3"><a name="APPROVAL_OF_FINISHED_ILLUSTRATIONS" id="APPROVAL_OF_FINISHED_ILLUSTRATIONS"></a>
+APPROVAL OF FINISHED ILLUSTRATIONS.</p>
+
+<p>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.</p>
+
+
+<p class="caption3"><a name="REVISION_OF_ILLUSTRATIONS" id="REVISION_OF_ILLUSTRATIONS"></a>
+REVISION OF ILLUSTRATIONS.</p>
+
+<p>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.</p>
+
+
+<p class="caption3"><a name="SUBMITTAL_OF_PROOFS" id="SUBMITTAL_OF_PROOFS"></a>
+SUBMITTAL OF PROOFS.</p>
+
+<p>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.</p>
+
+<p>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:</p>
+
+<p>1. Changes can not be made in zinc etchings except by eliminating
+parts, cutting away defects, and connecting lines. If additions are
+<span class="pagenum"><a name="Page_39" id="Page_39">[39]</a></span>
+required reengraving is generally necessary, and reengraving should
+preferably be avoided.</p>
+
+<p>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.</p>
+
+<p>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 <a href="#Page_89">p. 89</a>.)</p>
+
+
+<p class="caption3"><a name="PROOF_READING_ILLUSTRATIONS" id="PROOF_READING_ILLUSTRATIONS"></a>
+PROOF READING ILLUSTRATIONS.</p>
+
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+<p class="caption3"><a name="GENERAL_CONSIDERATIONS" id="GENERAL_CONSIDERATIONS"></a>
+GENERAL CONSIDERATIONS.</p>
+
+<p>The following requirements are essential to obtain good original
+illustrations:</p>
+
+<p>1. The material selected should be pertinent and expressive; it
+should have the qualities essential to good illustrations.</p>
+
+<p><span class="pagenum"><a name="Page_40" id="Page_40">[40]</a></span></p>
+
+<p>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&mdash;preferably twice publication size&mdash;whether
+it is a simple diagram or a base map.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_41" id="Page_41">[41]</a></span></p>
+
+
+<p class="caption2"><a name="Part_II" id="Part_II"></a>
+<span class="smcap">Part II. Preparation By Draftsmen.</span></p>
+
+
+<p class="caption3"><a name="GENERAL_DIRECTIONS" id="GENERAL_DIRECTIONS"></a>
+GENERAL DIRECTIONS.</p>
+
+<p>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.</p>
+
+<p>Part I of this pamphlet contains some matter that is pertinent to
+final preparation and should be consulted by draftsmen.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_42" id="Page_42">[42]</a></span>
+of each process, and he should be able to prepare drawings for any
+specified reduction in a way to insure good, legible reproduction.</p>
+
+<p>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.</p>
+
+
+<p class="caption3"><a name="INSTRUMENTS" id="INSTRUMENTS"></a>
+INSTRUMENTS.</p>
+
+<p>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.</p>
+
+<table summary="Draftman's Instruments">
+<tr>
+  <td style="width:50%">Air brush and connections.<br />
+  &#160;&#160;Beam compass.<br />
+  &#160;&#160;Bow pen, drop spring.<br />
+  *Bow pen, steel spring.<br />
+  &#160;&#160;Bow pencil, steel spring.<br />
+  *Brushes, red sable.<br />
+  &#160;&#160;China saucers.<br />
+  *Color box.<br />
+  *Compass, pen and pencil points.<br />
+  &#160;&#160;Crayons, assorted colors.<br />
+  &#160;&#160;Curve rule, adjustable.<br />
+  *Dividers, plain.<br />
+  *Dividers, proportional.<br />
+  &#160;&#160;Dividers, steel spring.<br />
+  &#160;&#160;Drawing boards, several sizes.<br />
+  &#160;&#160;Eraser, glass.<br />
+  *Eraser, rubber, hard.<br />
+  *Eraser, rubber, soft.<br />
+  *Eraser, steel.<br />
+  &#160;&#160;Erasing shield.<br />
+  *French curves, xylonite.<br />
+  &#160;&#160;Microscope, low power and lenses.<br />
+  &#160;&#160;Palette knife.<br />
+  &#160;&#160;Pantograph.<br />
+  &#160;&#160;Pens, double-pointed.<br />
+  *Pens, Gillott's, Nos. 170, 290, 291.<br />
+  &#160;&#160;Pens, K. &amp; E., drawing. No. 3202.</td>
+  <td class="vtop" style="width:50%">Pens, Payzant's, 1 set.<br />
+  *Pencils, best quality, graded
+    leads.<br />
+  *Protractor.<br />
+  &#160;&#160;Railroad curves, pearwood, 1 set.<br />
+  &#160;&#160;Railroad pen.<br />
+  *Railroad pencil.<br />
+  &#160;&#160;Reading glass.<br />
+  *Reducing glass.<br />
+  *Ruling pen.<br />
+  &#160;&#160;Scale, boxwood, 12 inches long,<br />
+  &#160;&#160;&#160;&#160;&#160;with divisions of millimeters<br />
+  &#160;&#160;&#160;&#160;&#160;and inches.<br />
+  &#160;&#160;Scales, boxwood, triangular.<br />
+  &#160;&#160;Section liner (parallel ruling device).<br />
+  &#160;&#160;Straightedge, steel, 24 inches.<br />
+  &#160;&#160;Straightedge, steel, 36 inches,<br />
+  &#160;&#160;&#160;&#160;&#160;with divisions for hundredths<br />
+  &#160;&#160;&#160;&#160;&#160;of an inch and millimeters.<br />
+  *Straightedge, wood, 24 inches.<br />
+  &#160;&#160;Swivel or curve pen.<br />
+  &#160;&#160;Thumb tacks.<br />
+  &#160;&#160;Tracing point, steel.<br />
+  *Triangle, 45&deg;.<br />
+  *Triangle, 60&deg;.<br />
+  *T square, pearwood, xylonite edge.<br />
+  *Tweezers, dentist's.</td>
+</tr>
+</table>
+
+
+
+
+<p class="caption3">CLASSIFICATION OF MATERIAL.</p>
+
+
+<p>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
+<span class="pagenum"><a name="Page_43" id="Page_43">[43]</a></span>
+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.</p>
+
+<p>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 "<sup>1</sup>/<sub>2</sub> off," "<sup>1</sup>/<sub>4</sub> off" or
+"reduce <sup>1</sup>/<sub>2</sub>," "reduce <sup>1</sup>/<sub>4</sub>"), 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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="PREPARATION_OF_MAPS" id="PREPARATION_OF_MAPS"></a>
+PREPARATION OF MAPS.</p>
+
+
+<p class="caption3">PROJECTION.</p>
+
+<p>The base maps furnished by authors (see pp. <a href="#Page_13">13</a>-<a href="#Page_14">14</a>) 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 <a href="#Figure_5">fig. 5</a>) 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
+<span class="pagenum"><a name="Page_44" id="Page_44">[44]</a></span>
+are given in tables published by the Geological Survey<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">[6]</a> and the
+Coast and Geodetic Survey.<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">[7]</a> <a href="#Figure_5">Figure 5</a>, 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.</p>
+
+<div class="footnote"><p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">[6]</span></a> 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.</p></div>
+
+<div class="footnote"><p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">[7]</span></a> 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.</p></div>
+
+<div class="fig_center" style="width: 533px;">
+<a name="Figure_5" id="Figure_5"></a>
+<a href="images/figure05_lrg.png"><img src="images/figure05.png" width="533" height="348" alt="" /></a>
+<span class="caption">Figure 5.&mdash;Diagram illustrating method of projecting a map.</span>
+</div>
+
+<p>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.</p>
+
+<p>The method of projecting a map, illustrated in the accompanying
+diagram (<a href="#Figure_5">fig. 5</a>), is as follows: First draw a straight vertical line
+(A) through the middle of the sheet to represent the central meridian
+<span class="pagenum"><a name="Page_45" id="Page_45">[45]</a></span>
+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&deg; 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&deg; apart and dividing by 2.</p>
+
+<p>The distance between parallels that are 2&deg; apart, as shown in the
+diagram, may be computed from Table 6 of "Geographic tables and
+formulas," as follows:</p>
+
+<table summary="Distance">
+<tr>
+  <td></td>
+  <td>Meters.</td>
+  <td>Meters.</td>
+</tr>
+<tr>
+  <td>1&deg; of latitude on 37th parallel</td>
+  <td>= 100,975.1 &divide; 2 = </td>
+  <td class="tdr">55,487.5</td>
+</tr>
+<tr>
+  <td>1&deg; of latitude on 36th parallel</td>
+  <td class="tdr">= </td>
+  <td class="tdr">110,956.2</td>
+</tr>
+<tr>
+  <td>1&deg; of latitude on 35th parallel</td>
+  <td>= 110,937.6 &divide; 2 = </td>
+  <td class="bdb tdr">55,468.8</td>
+</tr>
+<tr>
+  <td>True distance from 35&deg; to 37&deg; latitude</td>
+  <td class="tdr">= </td>
+  <td class="tdr">221,912.5</td>
+</tr>
+</table>
+
+<p>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.</p>
+
+<p>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&mdash;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.</p>
+
+
+<p class="caption3">DETAILS OF BASE MAPS.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_46" id="Page_46">[46]</a></span>
+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 <a href="#Plate_IV">Plate IV</a>, but the size and weight of each line or symbol must
+depend on the size and character of the map.</p>
+
+
+<p class="caption3">TRANSFERRING OF COPYING.</p>
+
+<p class="caption4">TRACING.</p>
+
+<p>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&mdash;the drawing paper and the map&mdash;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.</p>
+
+<p>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.</p>
+
+<p>In the final preparation of a base map to be engraved and printed
+in colors&mdash;for example, black, blue, and brown&mdash;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
+<span class="pagenum"><a name="Page_47" id="Page_47">[47]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p class="caption4">CELLULOID TRANSFERRING.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Requisitions for celluloid prints are made on the form used for
+requesting photolithographic work.</p>
+
+<p class="caption4">SKETCHING BY RETICULATION.</p>
+
+<p>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.</p>
+
+<p class="caption4">THE "SHADOWLESS DRAFTING TABLE."</p>
+
+<p>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
+<span class="pagenum"><a name="Page_48" id="Page_48">[48]</a></span>
+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.</p>
+
+<p>Such a table has been installed in the section of illustrations, where
+it can be used by authors and others.</p>
+
+
+<p class="caption3">TOPOGRAPHIC FEATURES.</p>
+
+<p class="caption4">RELIEF.</p>
+
+<p>The effect of relief is expressed on a map by three methods&mdash;by
+contours, by hachures, and by shading. (See <a href="#Figure_6">fig. 6</a>.) 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.</p>
+
+<p><i>Contours.</i>&mdash;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
+<a href="#Page_47">p. 47</a>), or it may be transferred by tracing with graphite-coated
+paper (see <a href="#Page_46">p. 46</a>). 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 <a href="#Figure_6">fig. 6, A</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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_49" id="Page_49">[49]</a></span>
+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.</p>
+
+<div class="fig_center" style="width: 379px;">
+<a name="Figure_6" id="Figure_6"></a>
+<a href="images/figure06_lrg.png"><img src="images/figure06.png" width="379" height="525" alt="" /></a>
+<span class="caption">Figure 6.&mdash;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.</span>
+</div>
+
+<p>Certain contour lines are commonly accentuated on a map, generally
+every fourth or fifth line&mdash;that is, for a 10-foot interval every
+50-foot line, for a 20-foot interval every 100-foot line, for a 25-foot
+<span class="pagenum"><a name="Page_50" id="Page_50">[50]</a></span>
+interval every 100-foot line, for a 50-foot interval every 250-foot line,
+and for a 100-foot interval every 500-foot line.</p>
+
+<p><i>Hachuring.</i>&mdash;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&mdash;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. <a href="#Figure_6">Figure 6, B</a>, represents satisfactory hachuring.</p>
+
+<p><i>Hill shading.</i>&mdash;Relief is more easily expressed by shading than by
+hachuring. (See <a href="#Figure_6">fig. 6, C, D</a>.) 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.</p>
+
+<p>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&mdash;a semitransparent
+white paper with sufficient "tooth" or grain to cut the shading
+up into minute dots. The shadowless drafting table (see <a href="#Page_47">p. 47</a>)
+is especially useful for this purpose. On this oversheet register
+<span class="pagenum"><a name="Page_51" id="Page_51">[51]</a></span>
+marks should be placed at the four comers and at several other points,
+particularly at the intersection of parallels and meridians.</p>
+
+<p>For relief shading on small black and white maps Ross's hand-stipple
+drawing paper may be used. (See <a href="#Page_24">p. 24</a>.) 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 <a href="#Figure_6">fig. 6, C</a>.)
+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.</p>
+
+<p>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 <a href="#Figure_6">fig. 6, D</a>) or mezzotint as a separate plate
+made to overprint the map in another color.</p>
+
+<p class="caption4">HYDROGRAPHY.</p>
+
+<p><i>General directions.</i>&mdash;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
+<span class="pagenum"><a name="Page_52" id="Page_52">[52]</a></span>
+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.</p>
+
+<p>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," <a href="#LETTERING">p. 53</a>.)</p>
+
+<p><i>Water lining.</i>&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_IV" id="Plate_IV"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE IV</div>
+
+<div class="fig_center" style="width: 643px;">
+<img src="images/plate_iv_a.png" width="643" height="567" style="position:relative; top:4px;" alt="" />
+<img src="images/plate_iv_b.png" width="643" height="567" alt="" />
+</div>
+
+<p class="captionbm">SYMBOLS USED ON BASE MAPS</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_53" id="Page_53">[53]</a></span></p>
+
+
+<p class="caption3">CULTURAL FEATURES.</p>
+
+<p>The cultural features represented on a map include "the works of
+man"&mdash;not only cities, towns, buildings, bridges, railroads, and other
+roads, but State, county, and other boundary lines&mdash;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 <a href="#Plate_IV">Pl. IV</a>
+for corresponding symbols.)</p>
+
+<table style="width:80%" summary="Cultural Features">
+<tr>
+  <td>Aqueduct mains.<br />
+  Aqueduct tunnels.<br />
+  Bench marks.<br />
+  Boundary Lines.<br />
+  Boundary monuments.<br />
+  Breakwaters.<br />
+  Bridges.<br />
+  Buildings.<br />
+  Cable Lines.<br />
+  Camps.<br />
+  Canal locks.<br />
+  Canals.<br />
+  Cemeteries.<br />
+  Churches.<br />
+  Cities.<br />
+  County lines.<br />
+  Dams.<br />
+  District lines.<br />
+  Ditches.<br />
+  Electric power lines.<br />
+  Fences.<br />
+  Ferries.<br />
+  Fords.<br />
+  Gas wells.<br />
+  Hedges.</td>
+  <td class="vtop">Hospitals.<br />
+  Jetties.<br />
+  Land-grant lines.<br />
+  Land-section Lines.<br />
+  Levees.<br />
+  Mains.<br />
+  Mineral monuments.<br />
+  Mine tunnels.<br />
+  Mines.<br />
+  National forests.<br />
+  National parks.<br />
+  Oil tanks.<br />
+  Oil wells.<br />
+  Open cuts.<br />
+  Park boundaries.<br />
+  Paths.<br />
+  Pits.<br />
+  Post offices.<br />
+  Precinct lines.<br />
+  Prospects.<br />
+  Province lines.<br />
+  Quarries.<br />
+  Quarter-section lines.<br />
+  Railroads, steam or electric.</td>
+  <td class="vtop">Ranches.<br />
+  Reservation boundaries.<br />
+  Reservoirs.<br />
+  Roads.<br />
+  Ruins.<br />
+  Schoolhouses.<br />
+  Section comers.<br />
+  Section Lines.<br />
+  Settlements.<br />
+  Shafts.<br />
+  Streets.<br />
+  Telegraph Lines.<br />
+  Towns.<br />
+  Township comers.<br />
+  Townships.<br />
+  Trails.<br />
+  Tramways.<br />
+  Triangulation stations.<br />
+  Tunnels.<br />
+  Villages.<br />
+  Water mains.<br />
+  Water wells.<br />
+  Waterworks.<br />
+  Windmills.</td>
+</tr>
+</table>
+
+
+<p class="caption3"><a name="LETTERING" id="LETTERING"></a>LETTERING.</p>
+
+<p class="caption4">GENERAL DIRECTIONS.</p>
+
+<p>The cultural features are named on maps by letters of two distinct
+styles&mdash;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.</p>
+
+<p>The features shown on a topographic map may be broadly separated
+into four groups and are lettered as follows:</p>
+
+<p>Civil divisions (countries, States, counties, townships, land grants,
+reservations, cities, towns, villages, settlements, schools, lodges,
+ranches, etc.), roman capitals or capitals and lower case.</p>
+
+<p>Public works (railroads, tunnels, roads, canals, ferries, bridges,
+fords, dams, mains, mines, forts, trails, etc.), slanting gothic capitals
+(light) or capitals and lower case.</p>
+
+<p><span class="pagenum"><a name="Page_54" id="Page_54">[54]</a></span></p>
+
+<p>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.</p>
+
+<p>Hypsographic features (mountains, ranges, peaks, plateaus, cliffs,
+buttes, canyons, valleys, peninsulas, islands, capes, etc.), upright
+gothic capitals (light) or capitals and lower case.</p>
+
+<p>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&mdash;not to the left and
+directly on a line with it, as Tucson<b>o</b>, 17<b>o</b>, Dallas<b>o</b>, Carson<b>o</b>. 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.</p>
+
+<p>Draftsmen often draw bad forms for commas, quotation marks,
+apostrophes, and question marks. The following forms are correct:
+Comma , ; quotation marks "" ; apostrophe ' ; question mark ? .</p>
+
+<p class="caption4">LETTERING BY TYPE.</p>
+
+<p>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.</p>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_V" id="Plate_V"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE V</div>
+
+<a href="images/plate_v_lrg.png"><img src="images/plate_v.png" width="385" height="624" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+
+<p class="captionbm">REDUCTION SHEET USED IN LETTERING ILLUSTRATIONS.<br />
+<br />
+The largest size shows the letters unreduced; the other sizes show the letters
+reduced as indicated in the margin.</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_55" id="Page_55">[55]</a></span></p>
+
+<p>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.</p>
+
+<p>Most of the styles and sizes of type now used on maps in the Survey's
+reports are shown in <a href="#Plate_V">Plate V</a>.</p>
+
+<p>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.
+<a href="#Plate_V">Plate V</a> shows a part of this reduction sheet.</p>
+
+<p class="caption4">ABBREVIATIONS.</p>
+
+<p>The following are the correct forms for abbreviations used on
+maps and other illustrations:</p>
+
+<table style="width:80%" summary="Abbreviations">
+<tr>
+  <td class="vtop">
+  <table summary="Abbrev1">
+  <tr>
+    <td>A</td>
+    <td>Arroyo</td>
+  </tr>
+  <tr>
+    <td>B. M</td>
+    <td>Bench mark</td>
+  </tr>
+  <tr>
+    <td>Bdy</td>
+    <td>Boundary</td>
+  </tr>
+  <tr>
+    <td>Br</td>
+    <td>Branch, bridge</td>
+  </tr>
+  <tr>
+    <td>C</td>
+    <td>Cape</td>
+  </tr>
+  <tr>
+    <td>Can</td>
+    <td>Canal, canyon</td>
+  </tr>
+  <tr>
+    <td>Cem</td>
+    <td>Cemetery</td>
+  </tr>
+  <tr>
+    <td>Co</td>
+    <td>County</td>
+  </tr>
+  <tr>
+    <td>Cr</td>
+    <td>Creek</td>
+  </tr>
+  <tr>
+    <td>E</td>
+    <td>East</td>
+  </tr>
+  <tr>
+    <td>El</td>
+    <td>Elevation</td>
+  </tr>
+  <tr>
+    <td>Est</td>
+    <td>Estuary</td>
+  </tr>
+  <tr>
+    <td>Fk</td>
+    <td>Fork</td>
+  </tr>
+  <tr>
+    <td>Ft</td>
+    <td>Fort, foot</td>
+  </tr>
+  <tr>
+    <td>Gl</td>
+    <td>Gulch, glacier</td>
+  </tr>
+  <tr>
+    <td>Hrb</td>
+    <td>Harbor</td>
+  </tr>
+  <tr>
+    <td>I</td>
+    <td>Island</td>
+  </tr>
+  </table>
+  </td>
+  <td class="vtop">
+  <table summary="Abrev2">
+  <tr>
+    <td>Is</td>
+    <td>Islands</td>
+  </tr>
+  <tr>
+    <td>Jc</td>
+    <td>Junction</td>
+  </tr>
+  <tr>
+    <td>L</td>
+    <td>Lake</td>
+  </tr>
+  <tr>
+    <td>Lat</td>
+    <td>Latitude</td>
+  </tr>
+  <tr>
+    <td>Ldg</td>
+    <td>Landing</td>
+  </tr>
+  <tr>
+    <td>L. S. S</td>
+    <td>Life-saving station</td>
+  </tr>
+  <tr>
+    <td>L. H</td>
+    <td>Lighthouse</td>
+  </tr>
+  <tr>
+    <td>Long</td>
+    <td>Longitude</td>
+  </tr>
+  <tr>
+    <td>M. P</td>
+    <td>Milepost</td>
+  </tr>
+  <tr>
+    <td>M. M</td>
+    <td>Mineral monument</td>
+  </tr>
+  <tr>
+    <td>Mt</td>
+    <td>Mount</td>
+  </tr>
+  <tr>
+    <td>Mtn</td>
+    <td>Mountain</td>
+  </tr>
+  <tr>
+    <td>Mts</td>
+    <td>Mountains</td>
+  </tr>
+  <tr>
+    <td>N</td>
+    <td>North</td>
+  </tr>
+  <tr>
+    <td>Pen</td>
+    <td>Peninsula</td>
+  </tr>
+  </table>
+  </td>
+  <td class="vtop">
+  <table summary="Abbrev1">
+  <tr>
+    <td>Pk</td>
+    <td>Peak</td>
+  </tr>
+  <tr>
+    <td>P. O</td>
+    <td>Post office</td>
+  </tr>
+  <tr>
+    <td>Pt</td>
+    <td>Point</td>
+  </tr>
+  <tr>
+    <td>R</td>
+    <td>Range, river</td>
+  </tr>
+  <tr>
+    <td>Res</td>
+    <td>Reservation, reservoir</td>
+  </tr>
+  <tr>
+    <td>R. H</td>
+    <td>Road house</td>
+  </tr>
+  <tr>
+    <td>S</td>
+    <td>South</td>
+  </tr>
+  <tr>
+    <td>Sd</td>
+    <td>Sound</td>
+  </tr>
+  <tr>
+    <td>S. H</td>
+    <td>Schoolhouse</td>
+  </tr>
+  <tr>
+    <td>Sta</td>
+    <td>Station</td>
+  </tr>
+  <tr>
+    <td>Str</td>
+    <td>Stream</td>
+  </tr>
+  <tr>
+    <td>T</td>
+    <td>Township</td>
+  </tr>
+  <tr>
+    <td>Tel</td>
+    <td>Telegraph</td>
+  </tr>
+  <tr>
+    <td>W</td>
+    <td>West.</td>
+  </tr>
+  </table>
+  </td>
+</tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_56" id="Page_56">[56]</a></span></p>
+
+<p>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.</p>
+
+<p>Names of States and Territories should be abbreviated, where
+abbreviation is necessary, as follows:</p>
+
+<table style="width:50%" summary="States">
+<tr>
+  <td>Ala.</td>
+  <td>Ga.</td>
+  <td>Minn.</td>
+  <td>N. J.</td>
+  <td>Tenn.</td>
+</tr>
+<tr>
+  <td>Ariz.</td>
+  <td>Ill.</td>
+  <td>Miss.</td>
+  <td>N. Mex.</td>
+  <td>Tex.</td>
+</tr>
+<tr>
+  <td>Ark.</td>
+  <td>Ind.</td>
+  <td>Mo.</td>
+  <td>N. Y.</td>
+  <td>Va.</td>
+</tr>
+<tr>
+  <td>Calif.</td>
+  <td>Kans.</td>
+  <td>Mont.</td>
+  <td>Okla.</td>
+  <td>Vt.</td>
+</tr>
+<tr>
+  <td>Colo.</td>
+  <td>Ky.</td>
+  <td>Nebr.</td>
+  <td>Oreg.</td>
+  <td>Wash.</td>
+</tr>
+<tr>
+  <td>Conn.</td>
+  <td>La.</td>
+  <td>Nev.</td>
+  <td>Pa.</td>
+  <td>W. Va.</td>
+</tr>
+<tr>
+  <td>D. C.</td>
+  <td>Mass.</td>
+  <td>N. C.</td>
+  <td>R. I.</td>
+  <td>Wis.</td>
+</tr>
+<tr>
+  <td>Del.</td>
+  <td>Md.</td>
+  <td>N. Dak.</td>
+  <td>S. C.</td>
+  <td>Wyo.</td>
+</tr>
+<tr>
+  <td>Fla.</td>
+  <td>Mich.</td>
+  <td>N. H.</td>
+  <td>S. Dak.</td>
+</tr>
+</table>
+
+<p>Alaska, Guam, Hawaii, Idaho, Iowa, Maine, Ohio, Samoa, and
+Utah should be written in full.</p>
+
+<p>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. <sup>1</sup>/<sub>2</sub> NE. <sup>1</sup>/<sub>4</sub> sec. 1, T. 7 N., K 2 W.; fractional secs. 2 and 35, Tps.
+7 and 8 N., R. 2 W.; NW. <sup>1</sup>/<sub>4</sub> sec. 20, T, 7 N., R. 2 W. In spelling
+fractions use half and quarter, not one-half and one-quarter.</p>
+
+<p>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.</p>
+
+<p>Additional abbreviations used on illustrations are as follows:</p>
+
+<div class="blockquot"><p>N. for north, NE. for northeast, NNE. for north-northeast, etc. Capitalize
+directions affixed to street names, as NW., SE. (1800 F St. NW.).</p>
+
+<p>Sec. and secs. for section and sections before a number. Capitalize only at the
+beginning of a line or sentence.</p>
+
+<p>a. m. and p. m. for antemeridian and postmeridian, as 4.30 p. m. Lower-case
+unless in line of caps.</p>
+
+<p>&amp; in names of corporations or companies. On Survey miscellaneous maps
+"and" is spelled out in railroad names.</p>
+
+<p>B. t. u. for British thermal units.</p>
+
+<p>bbl., bbls. for barrel, barrels.</p>
+
+<p>bu. for bushel or bushels.</p>
+
+<p>c. c. for cubic centimeter.</p>
+
+<p>cm. for centimeter.</p>
+
+<p>cwt. for hundredweight.</p>
+
+<p>dwt. or pwt. for pennyweight</p>
+
+<p>oz. for ounce or ounces.</p>
+
+<p>etc. (not &amp;c.) for et cetera.</p>
+
+<p>ft. for foot or feet.</p>
+
+<p>H. m. s. for hours, minutes, and seconds. (Use capital H.)</p>
+
+<p>in. for inch or inches.</p>
+
+<p>kw. for kilowatt or kilowatts.</p>
+
+<p>&pound; s. d. for pounds, shillings, and pence.</p>
+
+<p>per cent (omitting period) for per centum. Spell out percentage.</p>
+
+<p>ser. for series.</p>
+
+<p>St. for Saint or street</p>
+
+<p>U. S. Army for United States Army, as distinguished from United States of
+America (U. S. A.).</p>
+
+<p>yd., yds. for yard, yards.</p></div>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_VI" id="Plate_VI"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE VI</div>
+
+<a href="images/plate_vi_lrg.png"><img src="images/plate_vi.png" width="367" height="601" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+
+<p class="captionbm">HALF-TONE CUTS SHOWING EFFECT OF SEVERAL STANDARD
+SCREENS IN THE REPRODUCTION OF THE SAME DETAIL.</p>
+</div>
+
+
+<p><span class="pagenum"><a name="Page_57" id="Page_57">[57]</a></span></p>
+
+<p>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:</p>
+
+<table style="width:40%" summary="Months">
+<tr>
+  <td>Jan.</td>
+  <td>Apr.</td>
+  <td>July</td>
+  <td>Oct.</td>
+</tr>
+<tr>
+  <td>Feb.</td>
+  <td>May</td>
+  <td>Aug.</td>
+  <td>Nov.</td>
+</tr>
+<tr>
+  <td>Mar.</td>
+  <td>June</td>
+  <td>Sept</td>
+  <td>Dec.</td>
+</tr>
+</table>
+
+<p>The abbreviations for number and numbers before figures are No.
+and Nos. The o should never be raised, as in N<sup>o</sup>. The abbreviation
+for Mac is Mc, not M<sup>c</sup>.</p>
+
+<p>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.</p>
+
+<p class="caption4">NAMES OF RAILROADS.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">MAKE-UP OF MAPS.</p>
+
+<p class="caption4">FORMS FOR CERTAIN FEATURES.</p>
+
+<p>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
+<a href="#Plate_VII">Plate VII</a>. Note particularly the style and position of the marginal
+matter.</p>
+
+<p class="caption4">BORDER.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_58" id="Page_58">[58]</a></span>
+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<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">[8]</a> 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 = <sup>5</sup>/<sub>16</sub> inch.</p>
+
+<div class="footnote"><p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">[8]</span></a> Worked out by Martin Solem, of the U. S. Geological Survey.</p></div>
+
+<p>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.</p>
+
+<p class="caption4">TITLE.</p>
+
+<p>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</p>
+
+<p class="caption3">MAP OF BUTTE AND VICINITY, MONTANA<br />
+<span class="smaller">SHOWING LOCATION OF MINES AND PROSPECTS.</span></p>
+
+<p>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:</p>
+
+<p class="caption3" style="line-height:1.25em;"><span class="smaller">MAP OF</span><br />
+THE VICINITY OF BUTTE<br />
+MONTANA<br />
+<span class="smaller">SHOWING LOCATION OF MINES AND PROSPECTS.</span></p>
+
+<p>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 <a href="#Plate_VII">PI. VII</a>.)</p>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_VII" id="Plate_VII"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE VII</div>
+
+<a href="images/plate_vii_lrg.png"><img src="images/plate_vii.png" width="407" height="695" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+
+<p class="captionbm">DETAILS OF THE MAKE-UP OF A GEOLOGIC MAP</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_59" id="Page_59">[59]</a></span></p>
+
+<p class="caption4">EXPLANATION.</p>
+
+<p>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 <a href="#Plate_VII">Plate VII</a>, 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 <a href="#Plate_VII">Plate VII</a>, or horizontally under the
+title. A geologic explanation should preferably be arranged vertically,
+as in <a href="#Plate_VII">Plate VII</a>, 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.</p>
+
+<p>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 <a href="#Plate_VII">Plate VII</a>. 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.</p>
+
+<p>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.</p>
+
+<p class="caption4">GRAPHIC SCALES FOR MAPS.</p>
+
+<p>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 <a href="#Figure_7">figure 7</a>. The scale should be accompanied
+W any necessary statement pertaining to the base map, such as "Contour
+interval 20 feet," "Datum is mean sea level." The fractional
+scale (<img src="images/scale.png" width="43" height="27" style="position: relative; top: 0.5em;" alt="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 <a href="#Figure_7">figure 7</a> were made over blue prints from
+scales used by the Survey.</p>
+
+<p><span class="pagenum"><a name="Page_60" id="Page_60">[60]</a></span></p>
+
+<p>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 (<i>a</i> in <a href="#Figure_8">fig. 8</a>)
+representing this distance on the map, and at
+its end, at right angles
+to it, draw another line (<i>b</i>)
+actually measuring 16.315
+units of any convenient denomination.
+Draw a
+straight line (c) diagonally
+between the ends of lines
+<i>a</i> and <i>b</i>. Then set off on line
+<i>b</i> any convenient number
+of the units selected, say 5
+or 10, and project from the
+points set off lines exactly
+parallel with line <i>c</i> to line
+<i>a</i>. 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 <a href="#Figure_8">figure 8</a>.</p>
+
+<div class="fig_center" style="width: 493px;">
+<a name="Figure_7" id="Figure_7"></a>
+<img src="images/figure07.png" width="493" height="337" alt="" />
+<span class="caption">Figure 7.&mdash;Designs for bar scales.</span>
+</div>
+
+<div class="fig_center" style="width: 286px;">
+<a name="Figure_8" id="Figure_8"></a>
+<img src="images/figure08.png" width="286" height="397" alt="" />
+<span class="caption">Figure 8.&mdash;Method of making a bar scale for a
+map of unknown scale.</span>
+</div>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_VIII" id="Plate_VIII"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE VIII</div>
+
+<img src="images/plate_viii_a.png" width="639" height="601" alt="" />
+<img src="images/plate_viii_b.png" width="639" height="501" alt="" />
+
+<p class="captionbm">PATTERNS USED TO SHOW DISTINCTIONS BETWEEN
+AREAS ON BLACK AND WHITE MAPS<br />
+<br />
+Contrasts may be increased by varying the direction
+and spacing of Lines</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_61" id="Page_61">[61]</a></span></p>
+
+<p class="caption4">SYMBOLS.</p>
+
+<p>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 <a href="#Plate_II">Plate II</a>
+(<a href="#Plate_II">p. 20</a>) should be
+used in all the Survey's illustrations where they are appropriate.</p>
+
+<p class="caption4">AREAL PATTERNS FOR BLACK AND WHITE MAPS.</p>
+
+<p>The conventional patterns used on a map to distinguish separate
+areas, chiefly geologic, are shown in <a href="#Plate_VIII">Plate VIII</a>. 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&deg; 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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_62" id="Page_62">[62]</a></span>
+order to produce uniformly even spacing. The application of six of
+these conventional patterns to a base map is shown in <a href="#Figure_9">figure 9</a>.</p>
+
+<div class="fig_center" style="width: 373px;">
+<a name="Figure_9" id="Figure_9"></a>
+<a href="images/figure09_lrg.png"><img src="images/figure09.png" width="373" height="607" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+<p class="caption">Figure 9.&mdash;Map bearing six areal line patterns.</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_63" id="Page_63">[63]</a></span></p>
+
+<p class="caption4">STANDARD COLORS FOR GEOLOGIC MAPS.</p>
+
+<p>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 (<span class="x2">Q</span>), ochraceous orange; Tertiary (<span class="x2">T</span>), <i>yellow ocher</i> and
+<i>isabella color</i>; Cretaceous (<span class="x2">K</span>), <i>olive-green</i> or <i>rainette-green</i>; Jurassic
+(<span class="x2">J</span>), <i>blue-green</i> or <i>niagara-green</i>; Triassic (<img src="images/txt_tria.png" width="19" height="22" alt="TR" title="TR" style="position: relative; top:6px;" />), <i>light peacock-blue</i>
+or <i>bluish gray-green</i>; Carboniferous (<span class="x2">C</span>), <i>blue</i> or <i>columibia-blue</i>;
+Devonian (<span class="x2">D</span>), <i>gray-purple</i> or <i>heliotrope-gray</i>; Silurian (<span class="x2">S</span>), <i>purple</i>
+or <i>argyle-purple</i>; Ordovician (<span class="x2">O</span>), <i>red-purple</i> or <i>rocellin-purple</i>;
+Cambrian (<img src="images/txt_camb.png" width="16" height="16" alt="-C" title="-C" style="position: relative; top:4px;" />), <i>brick-red</i> or <i>etruscan red</i>; Algonkian (<span class="x2">A</span>), <i>terra cotta</i>
+or <i>onion-skin pink</i>; Archean (<img src="images/txt_arch.png" width="19" height="15" alt="AR" title="AR" style="position: relative; top:4px;" />), <i>gray-brown</i> or <i>drab</i>.<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">[9]</a></p>
+
+<div class="footnote"><p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">[9]</span></a> Names printed in italic are from "Color standards and nomenclature," by Robert
+Ridgway.</p></div>
+
+<p class="caption4">REDUCTION OF ENLARGEMENT OF MAPS.</p>
+
+<p>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 <a href="#Figure_10">fig. 10</a>.) 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,<a name="FNanchor_10_10" id="FNanchor_10_10"></a>
+<a href="#Footnote_10_10" class="fnanchor">[10]</a> 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 <a href="#Figure_10">figure 10</a>. 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.</p>
+
+<div class="footnote"><p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">[10]</span></a>
+See U. S. Geol. Survey Bull. 650, p. 37. 1916.</p>
+
+<p><span class="pagenum"><a name="Page_64" id="Page_64">[64]</a></span></p></div>
+
+<p>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 "<sup>1</sup>/<sub>2</sub> off," "<sup>1</sup>/<sub>3</sub> off," "<sup>2</sup>/<sub>3</sub> off." If
+the size needed is not exactly represented by these fractions it should
+be indicated in inches, as "Reduce this line to 7<sup>1</sup>/<sub>2</sub> inches," or "Reduce
+to 4<sup>3</sup>/<sub>8</sub> inches in width."</p>
+
+<div class="fig_center" style="width: 535px;">
+<a name="Figure_10" id="Figure_10"></a>
+<a href="images/figure10_lrg.png"><img src="images/figure10.png" width="535" height="193" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+<p class="caption">Figure 10.&mdash;Diagram showing method of marking maps for reduction or enlargement
+(for record).</p>
+</div>
+
+
+<p class="caption2">DIAGRAMS.</p>
+
+<p>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 <a href="#Plate_IX">Pl. IX</a>), or it may be in roman.</p>
+
+<p>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.</p>
+
+
+<p class="caption2">SECTIONS.</p>
+
+<p>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 <a href="#Page_29">29</a>-<a href="#Page_30">30</a>, and the conventions used to express lithologic character
+are shown in <a href="#Plate_III">Plate III</a>.</p>
+
+<div class="center" style="width:100%; margin-top:1em;"><a name="Plate_IX" id="Plate_IX"></a>
+<div class="captionlf">U. S. GEOLOGICAL SURVEY</div>
+<div class="captionrt">PREPARATION OF ILLUSTRATIONS PLATE IX</div>
+
+<a href="images/plate_ix_lrg.png"><img src="images/plate_ix.png" width="410" height="689" alt="" /></a>
+
+<p class="captionbm">DIAGRAMS AND CURVES.</p>
+</div>
+
+<p><span class="pagenum"><a name="Page_65" id="Page_65">[65]</a></span></p>
+
+<p>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 <a href="#Figure_11">fig. 11</a>.)</p>
+
+<div class="fig_center" style="width: 506px;">
+<a name="Figure_11" id="Figure_11"></a>
+<a href="images/figure11_lrg.png"><img src="images/figure11.png" width="506" height="198" alt="" /></a>
+<p class="center smaller" style="color:#808080;">Click on image to view larger size.</p>
+
+<p class="caption">Figure 11.&mdash;Structure section showing method of determining the secession of folds.</p>
+</div>
+
+<p>Penciled lines corresponding to those shown by dots in <a href="#Figure_11">figure 11</a>
+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.</p>
+
+
+<p class="caption2">PLANS AND CROSS SECTIONS OF MINES.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_66" id="Page_66">[66]</a></span>
+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.</p>
+
+<p>The reduction of such drawings to the minimum scale consistent
+with clearness is always advisable.</p>
+
+
+
+
+<p class="caption2"><a name="DRAWINGS_OF_SPECIMENS" id="DRAWINGS_OF_SPECIMENS"></a>
+DRAWINGS OF SPECIMENS OF ROCKS AND FOSSILS.</p>
+
+
+<p class="caption3">METHODS USED.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">BRUSH AND PENCIL DRAWINGS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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;
+<span class="pagenum"><a name="Page_67" id="Page_67">[67]</a></span>
+the best quality of red sable brushes of the sizes of Winsor &amp; 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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">PEN DRAWINGS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.
+<span class="pagenum"><a name="Page_68" id="Page_68">[68]</a></span>
+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.</p>
+
+
+
+
+<p class="caption2"><a name="RETOUCHING_PHOTOGRAPHS_OF_SPECIMENS" id="RETOUCHING_PHOTOGRAPHS_OF_SPECIMENS"></a>RETOUCHING PHOTOGRAPHS OF SPECIMENS.</p>
+
+
+<p>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 &amp; 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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="LANDSCAPE_DRAWINGS_FROM_POOR_PHOTOGRAPHS" id="LANDSCAPE_DRAWINGS_FROM_POOR_PHOTOGRAPHS"></a>LANDSCAPE DRAWINGS FROM POOR PHOTOGRAPHS.</p>
+
+
+<p>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.</p>
+
+
+<p class="caption3">PEN DRAWINGS MADE OVER PHOTOGRAPHS.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_69" id="Page_69">[69]</a></span>
+<b>T</b> square and triangle. For specimen or landscape work it need not
+be fastened.</p>
+
+<p>For bleaching blue prints a saturated solution of oxalate of potassium
+(K<sub>2</sub>C<sub>2</sub>O<sub>4</sub> + H<sub>2</sub>O) 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.</p>
+
+
+<p class="caption3">BRUSH DRAWINGS FROM POOR PHOTOGRAPHS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Plates I, IV, <i>A</i>, V, <i>B</i>, and VII, <i>B</i>, Monograph 34, were made from
+gouache drawings. Plates III, <i>A</i>, VII, <i>A</i>, 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.</p>
+
+
+
+
+<p class="caption2"><a name="OUTDOOR_SKETCHES" id="OUTDOOR_SKETCHES"></a>OUTDOOR SKETCHES.</p>
+
+
+<p>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,
+<span class="pagenum"><a name="Page_70" id="Page_70">[70]</a></span>
+in their true perspective and relations, with the skill necessary to
+make them satisfactory illustrations.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="DRAWINGS_OF_CRYSTALS" id="DRAWINGS_OF_CRYSTALS"></a>DRAWINGS OF CRYSTALS.</p>
+
+
+<p>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&#8242;, m&#8243;, m&#8244;, m<sup><i>IV</i></sup>. "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: <span class="undrln">m</span>, <span class="dundrln">m</span>, <span class="ovrln">m</span>. Twin units may be differentiated
+by the use of roman numerals.</p>
+
+
+
+
+<p class="caption2"><a name="RETOUCHING_PHOTOGRAPHS" id="RETOUCHING_PHOTOGRAPHS"></a>RETOUCHING PHOTOGRAPHS.</p>
+
+
+<p>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
+<span class="pagenum"><a name="Page_71" id="Page_71">[71]</a></span>
+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.</p>
+
+<p>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&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Panoramas may also be drawn from photographs with either pen
+or brush in the manner described on pages 68-69.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum"><a name="Page_72" id="Page_72">[72]</a></span></p>
+
+
+
+
+<p class="caption2"><a name="PART_III" id="PART_III"></a>
+PART III. PROCESSES OF REPRODUCING ILLUSTRATIONS.</p>
+
+
+
+
+<p class="caption2"><a name="METHODS_EMPLOYED" id="METHODS_EMPLOYED"></a>METHODS EMPLOYED.</p>
+
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="PHOTO-ENGRAVING" id="PHOTO-ENGRAVING"></a>PHOTO-ENGRAVING.</p>
+
+
+<p class="caption3">GENERAL FEATURES</p>
+
+<p>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
+<span class="pagenum"><a name="Page_73" id="Page_73">[73]</a></span>
+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.</p>
+
+
+<p class="caption3">ZINC ETCHING.</p>
+
+<p>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&mdash;that
+is, by hand&mdash;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.</p>
+
+<p>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&mdash;the
+<span class="pagenum"><a name="Page_74" id="Page_74">[74]</a></span>
+picture&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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 <a href="#Page_24">p. 24</a>.) 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.</p>
+
+<p><span class="pagenum"><a name="Page_75" id="Page_75">[75]</a></span></p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">COPPER ETCHING IN RELIEF.</p>
+
+<p>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.</p>
+
+<p>The chemical part of the process is practically the same as that
+employed for etching half-tone plates, described under the next
+heading.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">HALF-TONE ENGRAVING.</p>
+
+<p>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&mdash;the half tones&mdash;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.</p>
+
+<p>The half-tone screen consists of two plates of glass, on each of
+which lines running generally at an angle of 45&deg; 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
+<span class="pagenum"><a name="Page_76" id="Page_76">[76]</a></span>
+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 <a href="#Plate_IV">Pl. VI, p. 56.</a>)</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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&mdash;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
+<span class="pagenum"><a name="Page_77" id="Page_77">[77]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>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 <a href="#Page_74">p. 74</a>.) 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"&mdash;or more properly shade&mdash;between and around the several
+figures must be removed and numbers must be added. This operation
+requires two negatives&mdash;one half tone and one line&mdash;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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_78" id="Page_78">[78]</a></span>
+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.</p>
+
+<p>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, <i>A</i>, VI, <i>A</i>, and XV, figure
+10, and other illustrations in Survey Monograph 34.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Half tones etched on zinc (100-line screen or coarser) cost 25 per
+cent less than those etched on copper.</p>
+
+
+<p class="caption3">THREE-COLOR HALF-TONE PROCESS.</p>
+
+<p>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&mdash;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
+<span class="pagenum"><a name="Page_79" id="Page_79">[79]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>The ordinary half-tone screen, which bears lines cut at an angle of
+45&deg; 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.</p>
+
+<p>As special experience is necessary in printing three-color plates the
+engraver generally delivers the printed illustrations to the purchaser
+<span class="pagenum"><a name="Page_80" id="Page_80">[80]</a></span>
+instead of the plates, which he furnishes for other kinds of relief
+printing.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="WAX_ENGRAVING_THE_CEROTYPE_PROCESS" id="WAX_ENGRAVING_THE_CEROTYPE_PROCESS"></a>WAX ENGRAVING (THE CEROTYPE PROCESS).</p>
+
+
+<p>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&mdash;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.</p>
+
+<p>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,
+<span class="pagenum"><a name="Page_81" id="Page_81">[81]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2">WOOD ENGRAVING.</p>
+
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_82" id="Page_82">[82]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2">PHOTOGELATIN PROCESSES.</p>
+
+
+<p>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.</p>
+
+<p>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&deg; 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
+<span class="pagenum"><a name="Page_83" id="Page_83">[83]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>The photogelatin process is well adapted to the reproduction of
+paleontologic drawings, wash drawings, photographs, photomicrographs,
+works of art, old manuscripts&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="LITHOGRAPHY" id="LITHOGRAPHY"></a>LITHOGRAPHY.</p>
+
+
+<p class="caption3">ORIGINAL PROCESS.</p>
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_84" id="Page_84">[84]</a></span>
+adhere only to the parts that are covered with the crayon, and that
+the stone will give off an impression of the design.</p>
+
+<p>Lithographic stone is described as a fine, compact, homogeneous
+limestone, which may be either a pure carbonate of lime or dolomitic&mdash;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.<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">[11]</a> 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.</p>
+
+<div class="footnote"><p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">[11]</span></a> Kubel, S. J., Lithographic stone: U. S. Geol. Survey Mineral Resources, 1900, pp.
+869-873, 1901.</p></div>
+
+<p>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&mdash;not reversed.</p>
+
+<p>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"&mdash;that is, it is covered with a solution of
+gum arabic and nitric acid&mdash;and dried. The stone is then dampened
+with water and carefully rolled with lithographic ink, which adheres
+<span class="pagenum"><a name="Page_85" id="Page_85">[85]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_86" id="Page_86">[86]</a></span>
+cylinder the printing is rapid; but the best printing from a metal
+plate is inferior to the best printing from a lithographic stone.</p>
+
+
+<p class="caption3">PHOTOLITHOGRAPHY.</p>
+
+<p>Photolithography, like other lithographic processes, has been improved
+greatly during the last few years&mdash;not particularly in results
+but in methods&mdash;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.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_87" id="Page_87">[87]</a></span></p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">OFFSET PRINTING.</p>
+
+<p>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
+<a href="#Plate_II">II</a>, <a href="#Plate_III">III</a>,
+<a href="#Plate_IV">IV</a>, <a href="#Plate_VII">VII</a>,
+and <a href="#Plate_VIII">VIII</a> in this pamphlet were printed by this
+process.</p>
+
+
+<p class="caption3">CHROMOLITHOGRAPHY.</p>
+
+<p>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.</p>
+
+<p><span class="pagenum"><a name="Page_88" id="Page_88">[88]</a></span></p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_89" id="Page_89">[89]</a></span>
+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&mdash;that is, subject to the corrections and changes indicated
+on the proofs&mdash;and to hold the lithographer responsible for any
+failure to make the corrections.</p>
+
+<p>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.</p>
+
+
+<p class="caption3">ENGRAVING ON STONE AND ON COPPER.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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
+<span class="pagenum"><a name="Page_90" id="Page_90">[90]</a></span>
+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.</p>
+
+<p>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.</p>
+
+<p>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&mdash;generally a thin printing ink&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum"><a name="Page_91" id="Page_91">[91]</a></span></p>
+
+
+
+
+<p class="caption2"><a name="APPENDIX" id="APPENDIX"></a>APPENDIX.</p>
+
+
+<p>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.</p>
+
+
+
+
+<p class="caption2"><a name="MISCELLANEOUS_TABLES" id="MISCELLANEOUS_TABLES"></a>
+MISCELLANEOUS TABLES.</p>
+
+
+<p class="p0 pmb1 center"><i>Length of 1&deg; of longitude measured along given parallels from the Equator to
+the poles.</i><br />
+<br />
+[From U. S. Coast and Geodetic Survey Report for 1884, Appendix 6.]<br /></p>
+
+<table style="width:40em" summary="Distance">
+<tr>
+  <td class="bdt bdb">
+  <table style="width:100%" summary="col1">
+  <tr>
+    <td class="bdt bdb">Parallel of<br />latitude.</td>
+    <td class="bdt bdb">Statute miles.</td>
+  </tr>
+  <tr>
+    <td class="tdr2">0</td>
+    <td class="tdr2">69.172</td>
+  </tr>
+  <tr>
+    <td class="tdr2">1</td>
+    <td class="tdr2">69.162</td>
+  </tr>
+  <tr>
+    <td class="tdr2">2</td>
+    <td class="tdr2">69.130</td>
+  </tr>
+  <tr>
+    <td class="tdr2">3</td>
+    <td class="tdr2">69.078</td>
+  </tr>
+  <tr>
+    <td class="tdr2">4</td>
+    <td class="tdr2">69.005</td>
+  </tr>
+  <tr>
+    <td class="tdr2">5</td>
+    <td class="tdr2">68.911</td>
+  </tr>
+  <tr>
+    <td class="tdr2">6</td>
+    <td class="tdr2">68.795</td>
+  </tr>
+  <tr>
+    <td class="tdr2">7</td>
+    <td class="tdr2">68.660</td>
+  </tr>
+  <tr>
+    <td class="tdr2">8</td>
+    <td class="tdr2">68.504</td>
+  </tr>
+  <tr>
+    <td class="tdr2">9</td>
+    <td class="tdr2">68.326</td>
+  </tr>
+  <tr>
+    <td class="tdr2">10</td>
+    <td class="tdr2">68.129</td>
+  </tr>
+  <tr>
+    <td class="tdr2">11</td>
+    <td class="tdr2">67.910</td>
+  </tr>
+  <tr>
+    <td class="tdr2">12</td>
+    <td class="tdr2">67.670</td>
+  </tr>
+  <tr>
+    <td class="tdr2">13</td>
+    <td class="tdr2">67.410</td>
+  </tr>
+  <tr>
+    <td class="tdr2">14</td>
+    <td class="tdr2">67.131</td>
+  </tr>
+  <tr>
+    <td class="tdr2">15</td>
+    <td class="tdr2">66.830</td>
+  </tr>
+  <tr>
+    <td class="tdr2">16</td>
+    <td class="tdr2">66.510</td>
+  </tr>
+  <tr>
+    <td class="tdr2">17</td>
+    <td class="tdr2">66.169</td>
+  </tr>
+  <tr>
+    <td class="tdr2">18</td>
+    <td class="tdr2">65.808</td>
+  </tr>
+  <tr>
+    <td class="tdr2">19</td>
+    <td class="tdr2">65.427</td>
+  </tr>
+  <tr>
+    <td class="tdr2">20</td>
+    <td class="tdr2">65.026</td>
+  </tr>
+  <tr>
+    <td class="tdr2">21</td>
+    <td class="tdr2">64.606</td>
+  </tr>
+  <tr>
+    <td class="tdr2">22</td>
+    <td class="tdr2">64.166</td>
+  </tr>
+  <tr>
+    <td class="tdr2">23</td>
+    <td class="tdr2">63.706</td>
+  </tr>
+  <tr>
+    <td class="tdr2">24</td>
+    <td class="tdr2">63.228</td>
+  </tr>
+  <tr>
+    <td class="tdr2">25</td>
+    <td class="tdr2">62.729</td>
+  </tr>
+  <tr>
+    <td class="tdr2">26</td>
+    <td class="tdr2">62.212</td>
+  </tr>
+  <tr>
+    <td class="tdr2">27</td>
+    <td class="tdr2">61.676</td>
+  </tr>
+  <tr>
+    <td class="tdr2">28</td>
+    <td class="tdr2">61.122</td>
+  </tr>
+  <tr>
+    <td class="tdr2">29</td>
+    <td class="tdr2">60.548</td>
+  </tr>
+  <tr>
+    <td class="bdb tdr2">30</td>
+    <td class="bdb tdr2">59.956</td>
+  </tr>
+  </table>
+  </td>
+  <td class="bdt bdb bdl2 vtop">
+  <table style="width:100%" summary="col2">
+  <tr>
+    <td class="bdt bdb bdl2">Parallel of<br />latitude.</td>
+    <td class="bdt bdb">Statute miles.</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">31</td>
+    <td class="tdr2">59.365</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">32</td>
+    <td class="tdr2">58.716</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">33</td>
+    <td class="tdr2">58.071</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">34</td>
+    <td class="tdr2">67.407</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">35</td>
+    <td class="tdr2">66.725</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">36</td>
+    <td class="tdr2">66.027</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">37</td>
+    <td class="tdr2">65.311</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">38</td>
+    <td class="tdr2">64.679</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">39</td>
+    <td class="tdr2">63.829</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">40</td>
+    <td class="tdr2">53.063</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">41</td>
+    <td class="tdr2">62.281</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">42</td>
+    <td class="tdr2">51.483</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">43</td>
+    <td class="tdr2">60.669</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">44</td>
+    <td class="tdr2">49.840</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">45</td>
+    <td class="tdr2">48.995</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">46</td>
+    <td class="tdr2">48.136</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">47</td>
+    <td class="tdr2">47.261</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">48</td>
+    <td class="tdr2">46.372</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">49</td>
+    <td class="tdr2">45.469</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">50</td>
+    <td class="tdr2">44.652</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">51</td>
+    <td class="tdr2">43.621</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">52</td>
+    <td class="tdr2">42.676</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">53</td>
+    <td class="tdr2">41.719</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">54</td>
+    <td class="tdr2">40.749</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">55</td>
+    <td class="tdr2">39.766</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">56</td>
+    <td class="tdr2">38.771</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">57</td>
+    <td class="tdr2">37.764</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">58</td>
+    <td class="tdr2">36.745</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">59</td>
+    <td class="tdr2">35.716</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">60</td>
+    <td class="tdr2">34.674</td>
+  </tr>
+  <tr>
+    <td class="bdb bdl2">&nbsp;</td>
+    <td class="bdb"></td>
+  </tr>
+  </table>
+  </td>
+  <td class="bdt bdb bdl2 vtop">
+  <table style="width:100%" summary="col3">
+  <tr>
+    <td class="bdt bdb bdl2">Parallel of<br />latitude.</td>
+    <td class="bdt bdb">Statute miles.</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">61</td>
+    <td class="tdr2">33.623</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">62</td>
+    <td class="tdr2">32.560</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">63</td>
+    <td class="tdr2">31.488</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">64</td>
+    <td class="tdr2">30.406</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">65</td>
+    <td class="tdr2">29.315</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">66</td>
+    <td class="tdr2">28.215</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">67</td>
+    <td class="tdr2">27.106</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">68</td>
+    <td class="tdr2">26.988</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">69</td>
+    <td class="tdr2">24.862</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">70</td>
+    <td class="tdr2">23.729</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">71</td>
+    <td class="tdr2">22.589</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">72</td>
+    <td class="tdr2">21.441</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">73</td>
+    <td class="tdr2">20.287</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">74</td>
+    <td class="tdr2">19.127</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">75</td>
+    <td class="tdr2">17.960</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">76</td>
+    <td class="tdr2">16.788</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">77</td>
+    <td class="tdr2">15.611</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">78</td>
+    <td class="tdr2">14.428</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">79</td>
+    <td class="tdr2">13.242</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">80</td>
+    <td class="tdr2">12.051</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">81</td>
+    <td class="tdr2">10.857</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">82</td>
+    <td class="tdr2">9.659</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">83</td>
+    <td class="tdr2">8.458</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">84</td>
+    <td class="tdr2">7.256</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">85</td>
+    <td class="tdr2">6.049</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">86</td>
+    <td class="tdr2">4.842</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">87</td>
+    <td class="tdr2">3.632</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">88</td>
+    <td class="tdr2">2.422</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">89</td>
+    <td class="tdr2">1.211</td>
+  </tr>
+  <tr>
+    <td class="tdr2 bdl2">90</td>
+    <td class="tdr2">.000</td>
+  </tr>
+  <tr>
+    <td class="bdb bdl2">&nbsp;</td>
+    <td class="bdb"></td>
+  </tr>
+  </table>
+  </td>
+</tr>
+</table>
+
+<p class="p0 center pmt2 pmb1"><i>Length of 1&deg; of latitude measured along a meridian at given parallels.</i><br />
+<br />
+[Parallel given is in center of the degree whose length is stated.]<br /></p>
+
+<table style="width:25em" summary="Length of One Degree">
+<tr>
+  <td class="bdt bdb bdl center">Parallel&nbsp;of<br />latitude.</td>
+  <td class="bdt bdb bdl center">Statute<br />miles.</td>
+  <td class="bdt bdb bdl2 center">Parallel&nbsp;of<br />latitude.</td>
+  <td class="bdt bdr bdb bdl center">Statute<br />miles.</td>
+</tr>
+<tr>
+    <td class="bdl tdr2">0</td>
+    <td class="bdl tdr2">68.704</td>
+    <td class="bdl2 tdr2">50</td>
+    <td class="bdl bdr tdr2">69.115</td>
+  </tr>
+  <tr>
+    <td class="bdl tdr2">10</td>
+    <td class="bdl tdr2">68.725</td>
+    <td class="bdl2 tdr2">60</td>
+    <td class="bdl bdr tdr2">69.230</td>
+  </tr>
+  <tr>
+    <td class="bdl tdr2">20</td>
+    <td class="bdl tdr2">68.786</td>
+    <td class="bdl2 tdr2">70</td>
+    <td class="bdl bdr tdr2">69.324</td>
+  </tr>
+  <tr>
+    <td class="bdl tdr2">30</td>
+    <td class="bdl tdr2">68.879</td>
+    <td class="bdl2 tdr2">80</td>
+    <td class="bdl bdr tdr2">69.386</td>
+  </tr>
+  <tr>
+    <td class="bdb bdl tdr2">40</td>
+    <td class="bdb bdl tdr2">68.993</td>
+    <td class="bdb bdl2 tdr2">90</td>
+    <td class="bdb bdl bdr tdr2">69.407</td>
+  </tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_92" id="Page_92">[92]</a></span></p>
+
+
+<p class="caption3">Metric system and equivalents.</p>
+
+<p class="pmb1 center">[The units of linear measure most commonly used are millimeters (mm.), centimeters (cm.),<br />
+decimeters (dm.), meters (m.), and kilometers (km.), 1 m. = 10 dm.; 1 dm. = 10 cm.;<br />
+1 cm. = 10 mm.; 1 km. = 1,000 meters = 0.62137 mile; 1 m. = 39.37 inches = 3.280833 feet.]</p>
+
+<table style="width:40em" summary="Metric Equivalents">
+<tr>
+  <td class="bdt bdb center">Meters.</td>
+  <td class="bdt bdb bdl center">Inches.</td>
+  <td class="bdt bdb bdl2 center">Meters.</td>
+  <td class="bdt bdb bdl center">Feet.</td>
+  <td class="bdt bdb bdl2 center">Kilometers.</td>
+  <td class="bdt bdb bdl center">Miles.</td>
+</tr>
+<tr>
+  <td class="tdr2">1</td>
+  <td class="bdl tdr2">39.37</td>
+  <td class="bdl2 tdr2">1</td>
+  <td class="bdl tdr2">3.280633</td>
+  <td class="bdl2 tdr2">1</td>
+  <td class="bdl tdr2">0.62137</td>
+</tr>
+<tr>
+  <td class="tdr2">2</td>
+  <td class="bdl tdr2">78.74</td>
+  <td class="bdl2 tdr2">2</td>
+  <td class="bdl tdr2">6.561667</td>
+  <td class="bdl2 tdr2">2</td>
+  <td class="bdl tdr2">1.24274</td>
+</tr>
+<tr>
+  <td class="tdr2">3</td>
+  <td class="bdl tdr2">118.11</td>
+  <td class="bdl2 tdr2">3</td>
+  <td class="bdl tdr2">9.842500</td>
+  <td class="bdl2 tdr2">3</td>
+  <td class="bdl tdr2">1.86411</td>
+</tr>
+<tr>
+  <td class="tdr2">4</td>
+  <td class="bdl tdr2">157.48</td>
+  <td class="bdl2 tdr2">4</td>
+  <td class="bdl tdr2">13.123333</td>
+  <td class="bdl2 tdr2">4</td>
+  <td class="bdl tdr2">2.48548</td>
+</tr>
+<tr>
+  <td class="tdr2">5</td>
+  <td class="bdl tdr2">196.85</td>
+  <td class="bdl2 tdr2">5</td>
+  <td class="bdl tdr2">16.404166</td>
+  <td class="bdl2 tdr2">5</td>
+  <td class="bdl tdr2">3.10685</td>
+</tr>
+<tr>
+  <td class="tdr2">6</td>
+  <td class="bdl tdr2">236.22</td>
+  <td class="bdl2 tdr2">6</td>
+  <td class="bdl tdr2">19.685000</td>
+  <td class="bdl2 tdr2">6</td>
+  <td class="bdl tdr2">3.72822</td>
+</tr>
+<tr>
+  <td class="tdr2">7</td>
+  <td class="bdl tdr2">275.59</td>
+  <td class="bdl2 tdr2">7</td>
+  <td class="bdl tdr2">22.965833</td>
+  <td class="bdl2 tdr2">7</td>
+  <td class="bdl tdr2">4.34959</td>
+</tr>
+<tr>
+  <td class="tdr2">8</td>
+  <td class="bdl tdr2">314.96</td>
+  <td class="bdl2 tdr2">8</td>
+  <td class="bdl tdr2">26.246666</td>
+  <td class="bdl2 tdr2">8</td>
+  <td class="bdl tdr2">4.97096</td>
+</tr>
+<tr>
+  <td class="bdb tdr2">9</td>
+  <td class="bdb bdl tdr2">354.33</td>
+  <td class="bdb bdl2 tdr2">9</td>
+  <td class="bdb bdl tdr2">29.527500</td>
+  <td class="bdb bdl2 tdr2">9</td>
+  <td class="bdb bdl tdr2">5.59233</td>
+</tr>
+<tr>
+  <td colspan="6">&nbsp;</td>
+</tr>
+<tr>
+  <td class="bdt bdb center">Inches.</td>
+  <td class="bdt bdb bdl center">Centimeters.</td>
+  <td class="bdt bdb bdl2 center">Feet.</td>
+  <td class="bdt bdb bdl center">Meters.</td>
+  <td class="bdt bdb bdl2 center">Miles.</td>
+  <td class="bdt bdb bdl center">Kilometers.</td>
+</tr>
+<tr>
+  <td class="tdr2">1</td>
+  <td class="bdl tdr2">2.54</td>
+  <td class="bdl2 tdr2">1</td>
+  <td class="bdl tdr2">0.304801</td>
+  <td class="bdl2 tdr2">1</td>
+  <td class="bdl tdr2">1.60935</td>
+</tr>
+<tr>
+  <td class="tdr2">2</td>
+  <td class="bdl tdr2">5.08</td>
+  <td class="bdl2 tdr2">2</td>
+  <td class="bdl tdr2">0.609601</td>
+  <td class="bdl2 tdr2">2</td>
+  <td class="bdl tdr2">3.21869</td>
+</tr>
+<tr>
+  <td class="tdr2">3</td>
+  <td class="bdl tdr2">7.62</td>
+  <td class="bdl2 tdr2">3</td>
+  <td class="bdl tdr2">0.914402</td>
+  <td class="bdl2 tdr2">3</td>
+  <td class="bdl tdr2">4.82804</td>
+</tr>
+<tr>
+  <td class="tdr2">4</td>
+  <td class="bdl tdr2">10.16</td>
+  <td class="bdl2 tdr2">4</td>
+  <td class="bdl tdr2">1.219202</td>
+  <td class="bdl2 tdr2">4</td>
+  <td class="bdl tdr2">6.43739</td>
+</tr>
+<tr>
+  <td class="tdr2">5</td>
+  <td class="bdl tdr2">12.70</td>
+  <td class="bdl2 tdr2">5</td>
+  <td class="bdl tdr2">1.524003</td>
+  <td class="bdl2 tdr2">5</td>
+  <td class="bdl tdr2">8.04674</td>
+</tr>
+<tr>
+  <td class="tdr2">6</td>
+  <td class="bdl tdr2">15.24</td>
+  <td class="bdl2 tdr2">6</td>
+  <td class="bdl tdr2">1.828804</td>
+  <td class="bdl2 tdr2">6</td>
+  <td class="bdl tdr2">9.65606</td>
+</tr>
+<tr>
+  <td class="tdr2">7</td>
+  <td class="bdl tdr2">17.78</td>
+  <td class="bdl2 tdr2">7</td>
+  <td class="bdl tdr2">2.133604</td>
+  <td class="bdl2 tdr2">7</td>
+  <td class="bdl tdr2">11.26543</td>
+</tr>
+<tr>
+  <td class="tdr2">8</td>
+  <td class="bdl tdr2">20.32</td>
+  <td class="bdl2 tdr2">8</td>
+  <td class="bdl tdr2">2.438405</td>
+  <td class="bdl2 tdr2">8</td>
+  <td class="bdl tdr2">12.87478</td>
+</tr>
+<tr>
+  <td class="bdb tdr2">9</td>
+  <td class="bdb bdl tdr2">22.86</td>
+  <td class="bdb bdl2 tdr2">9</td>
+  <td class="bdb bdl tdr2">2.743205</td>
+  <td class="bdb bdl2 tdr2">9</td>
+  <td class="bdb bdl tdr2">14.48412</td>
+</tr>
+</table>
+
+<p class="center pmt2 pmb2">The "vara," used in Texas, is equivalent to 33<sup>1</sup>/<sub>3</sub> inches and is computed as representing
+2.78 feet.</p>
+
+
+<p class="caption3"><i>Geologic eras, periods, systems, epochs, and series.</i></p>
+
+
+<table summary="Geological Names">
+<tr>
+  <td class="caption3">Era.</td>
+  <td class="caption3" colspan="2">Period or system.</td>
+  <td class="caption3" colspan="2">Epoch or series.</td>
+</tr>
+<tr>
+  <td rowspan="2">Cenozoic.</td>
+  <td rowspan="2"><img src="images/brace_l86.png" width="14" height="86" alt="" title="" /></td>
+  <td>Quaternary.</td>
+  <td><img src="images/brace_l40.png" width="11" height="40" alt="" title="" /></td>
+  <td>Recent.<br />Pleistocene (replaces "Glacial").</td>
+</tr>
+<tr>
+  <td>Tertiary.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Pliocene.<br />Miocene.<br />Oligocene.<br />Eocene.</td>
+</tr>
+<tr>
+  <td colspan="5">&nbsp;</td>
+</tr>
+<tr>
+  <td rowspan="3">Mesozoic.</td>
+  <td rowspan="3"><img src="images/brace_l155.png" width="11" height="155" alt="" title="" /></td>
+  <td>Cretaceous.</td>
+  <td><img src="images/brace_l40.png" width="11" height="40" alt="" title="" /></td>
+  <td>Upper (Gulf may be used provincially).<br />
+    Lower (Comanche and Shasta may be used provincially).</td>
+</tr>
+<tr>
+  <td>Jurassic.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Upper.<br />Middle.<br />Lower.</td>
+</tr>
+<tr>
+  <td>Triassic.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Upper.<br />Middle.<br />Lower.</td>
+</tr>
+<tr>
+  <td colspan="5">&nbsp;</td>
+</tr>
+<tr>
+  <td rowspan="5">Paleozoic.</td>
+  <td rowspan="5"><img src="images/brace_l240.png" width="11" height="240" alt="" title="" /></td>
+  <td>Carboniferous.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Permian.<br />Pennsylvanian (replaces "Upper Carboniferous").<br />Mississippian (replaces "Lower Carboniferous").</td>
+</tr>
+<tr>
+  <td>Devonian.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Upper.<br />Middle.<br />Lower.</td>
+</tr>
+<tr>
+  <td>Silurian.</td>
+  <td></td>
+  <td></td>
+</tr>
+<tr>
+  <td>Ordovician.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Upper (Cincinnatian may be used provincially).<br />Middle (Mohawkian may be used provincially).<br />Lower.</td>
+</tr>
+<tr>
+  <td>Cambrian.</td>
+  <td><img src="images/brace_l60.png" width="11" height="60" alt="" title="" /></td>
+  <td>Saratogan (or Upper Cambrian).<br />Acadian (or Middle Cambrian).<br />Waucoban (or Lower Cambrian).</td>
+</tr>
+<tr>
+  <td colspan="5">&nbsp;</td>
+</tr>
+<tr>
+  <td>Proterozoic.</td>
+  <td><img src="images/brace_l40.png" width="11" height="40" alt="" title="" /></td>
+  <td>Algonkian.<br />Archean.</td>
+  <td><img src="images/brace_r40.png" width="11" height="40" alt="" title="" /></td>
+  <td>&nbsp;pre-Cambrian.</td>
+</tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_93" id="Page_93">[93]</a></span></p>
+
+
+<p class="caption3"><i>Chemical elements and symbols.</i></p>
+
+<table class="padlf" style="width:45em" summary="Elements/Symbols">
+<tr>
+  <td class="bdt bdb">Element.</td>
+  <td class="bdt bdb" style="width:7em">Symbol.</td>
+  <td class="bdt bdb bdl2">&nbsp;</td>
+  <td class="bdt bdb">Element.</td>
+  <td class="bdt bdb" style="width:7em">Symbol.</td>
+  <td class="bdt bdb bdl2">&nbsp;</td>
+  <td class="bdt bdb">Element.</td>
+  <td class="bdt bdb" style="width:7em">Symbol.</td>
+</tr>
+<tr>
+  <td>Aluminum</td>
+  <td>Al</td>
+  <td class="bdb bdl2" rowspan="28"></td>
+  <td>Holmium</td>
+  <td>Ho</td>
+  <td class="bdb bdl2" rowspan="28"></td>
+  <td>Rhodium</td>
+  <td>Rh</td>
+</tr>
+<tr>
+  <td>Antimony</td>
+  <td>Sb</td>
+  <td>Hydrogen</td>
+  <td>H</td>
+  <td>Rubidium</td>
+  <td>Rb</td>
+</tr>
+<tr>
+  <td>Argon</td>
+  <td>Al</td>
+  <td>Indium</td>
+  <td>In</td>
+  <td>Ruthenium</td>
+  <td>Ru</td>
+</tr>
+<tr>
+  <td>Arsenic</td>
+  <td>As</td>
+  <td>Iodine</td>
+  <td>I</td>
+  <td>Samarium</td>
+  <td>Sa</td>
+</tr>
+<tr>
+  <td>Barium</td>
+  <td>Ba</td>
+  <td>Iridium</td>
+  <td>Ir</td>
+  <td>Scandium</td>
+  <td>Sc</td>
+</tr>
+<tr>
+  <td>Bismuth</td>
+  <td>Bi</td>
+  <td>Iron</td>
+  <td>Fe</td>
+  <td>Selenium</td>
+  <td>Se</td>
+</tr>
+<tr>
+  <td>Boron</td>
+  <td>B</td>
+  <td>Krypton</td>
+  <td>Kr</td>
+  <td>Silicon</td>
+  <td>Si</td>
+</tr>
+<tr>
+  <td>Bromine</td>
+  <td>Br</td>
+  <td>Lanthanum</td>
+  <td>La</td>
+  <td>Silver</td>
+  <td>Ag</td>
+</tr>
+<tr>
+  <td>Cadmium</td>
+  <td>Cd</td>
+  <td>Lead</td>
+  <td>Pb</td>
+  <td>Sodium</td>
+  <td>Na</td>
+</tr>
+<tr>
+  <td>Cesium</td>
+  <td>Cs</td>
+  <td>Lithium</td>
+  <td>Li</td>
+  <td>Strontium</td>
+  <td>Sr</td>
+</tr>
+<tr>
+  <td>Calcium</td>
+  <td>Ca</td>
+  <td>Lutecium</td>
+  <td>Lu</td>
+  <td>Sulphur</td>
+  <td>S</td>
+</tr>
+<tr>
+  <td>Carbon</td>
+  <td>C</td>
+  <td>Magnesium</td>
+  <td>Mg</td>
+  <td>Tantalum</td>
+  <td>Ta</td>
+</tr>
+<tr>
+  <td>Cerium</td>
+  <td>Ce</td>
+  <td>Manganese</td>
+  <td>Mn</td>
+  <td>Tellurium</td>
+  <td>Te</td>
+</tr>
+<tr>
+  <td>Chlorine</td>
+  <td>Cl</td>
+  <td>Mercury</td>
+  <td>Hg</td>
+  <td>Terbium</td>
+  <td>Tb</td>
+</tr>
+<tr>
+  <td>Chromium</td>
+  <td>Cr</td>
+  <td>Molybdenum</td>
+  <td>Mo</td>
+  <td>Thallium</td>
+  <td>Tl</td>
+</tr>
+<tr>
+  <td>Cobalt</td>
+  <td>Co</td>
+  <td>Neodymium</td>
+  <td>Nd</td>
+  <td>Thorium</td>
+  <td>Th</td>
+</tr>
+<tr>
+  <td>Columbium</td>
+  <td>C</td>
+  <td>Neon</td>
+  <td>Ne</td>
+  <td>Thulium</td>
+  <td>Tm</td>
+</tr>
+<tr>
+  <td>Copper</td>
+  <td>Cu</td>
+  <td>Nickel</td>
+  <td>Ni</td>
+  <td>Tin</td>
+  <td>Sn</td>
+</tr>
+<tr>
+  <td>Dysprosium</td>
+  <td>Dy</td>
+  <td>Niton</td>
+  <td>Nt</td>
+  <td>Titanium</td>
+  <td>Ti</td>
+</tr>
+<tr>
+  <td>Erbium</td>
+  <td>Er</td>
+  <td>Nitrogen</td>
+  <td>N</td>
+  <td>Tungsten</td>
+  <td>W</td>
+</tr>
+<tr>
+  <td>Europium</td>
+  <td>Eu</td>
+  <td>Osmium</td>
+  <td>Os</td>
+  <td>Uranium</td>
+  <td>U</td>
+</tr>
+<tr>
+  <td>Fluorine</td>
+  <td>F</td>
+  <td>Oxygen</td>
+  <td>O</td>
+  <td>Vanadium</td>
+  <td>V</td>
+</tr>
+<tr>
+  <td>Gadolinium</td>
+  <td>Gd</td>
+  <td>Palladium</td>
+  <td>Pd</td>
+  <td>Xenon</td>
+  <td>Xe</td>
+</tr>
+<tr>
+  <td>Gallium</td>
+  <td>Ga</td>
+  <td>Phosphorus</td>
+  <td>P</td>
+  <td>Ytterbium</td>
+</tr>
+<tr>
+  <td>Germanium</td>
+  <td>Ge</td>
+  <td>Platinum</td>
+  <td>Pt</td>
+  <td>&nbsp;&nbsp;(Neoytterbium)</td>
+  <td>Yb</td>
+</tr>
+<tr>
+  <td>Glucinum</td>
+  <td>Gl</td>
+  <td>Potassium</td>
+  <td>K</td>
+  <td>Yttrium</td>
+  <td>Y</td>
+</tr>
+<tr>
+  <td>Gold</td>
+  <td>Au</td>
+  <td>Praseodymium</td>
+  <td>Pr</td>
+  <td>Zinc</td>
+  <td>Zn</td>
+</tr>
+<tr>
+  <td class="bdb">Helium</td>
+  <td class="bdb">He</td>
+  <td class="bdb">Radium</td>
+  <td class="bdb">Ra</td>
+  <td class="bdb">Zirconium</td>
+  <td class="bdb">Zr</td>
+</tr>
+</table>
+
+
+<p class="caption3"><i>Greek alphabet.</i></p>
+
+<table style="width: 40em; text-align:center;" summary="Greek">
+<tr>
+  <td class="bdt bdb bdl">Caps.</td>
+  <td class="bdt bdb bdl">Lower-case.</td>
+  <td class="bdt bdb bdl">Greek name.</td>
+  <td class="bdt bdb bdl">English<br />sound.</td>
+  <td class="bdt bdb bdl" rowspan="13">&nbsp;</td>
+  <td class="bdt bdb bdl">Caps.</td>
+  <td class="bdt bdb bdl">Lower-case.</td>
+  <td class="bdt bdb bdl">Greek name.</td>
+  <td class="bdt bdr bdb bdl">English<br />sound.</td>
+</tr>
+<tr>
+  <td class="bdl">&#913;</td>
+  <td class="bdl">&#945;</td>
+  <td class="bdl">Alpha.</td>
+  <td class="bdl">A.</td>
+  <td class="bdl">&#925;</td>
+  <td class="bdl">&#957;</td>
+  <td class="bdl">Nu.</td>
+  <td class="bdl bdr">N.</td>
+</tr>
+<tr>
+  <td class="bdl">&#914;</td>
+  <td class="bdl">&#946;</td>
+  <td class="bdl">Beta.</td>
+  <td class="bdl">B.</td>
+  <td class="bdl">&#926;</td>
+  <td class="bdl">&#958;</td>
+  <td class="bdl">Xi.</td>
+  <td class="bdl bdr">X.</td>
+</tr>
+<tr>
+  <td class="bdl">&#915;</td>
+  <td class="bdl">&#947;</td>
+  <td class="bdl">Gamma.</td>
+  <td class="bdl">G.</td>
+  <td class="bdl">&#927;</td>
+  <td class="bdl">&#959;</td>
+  <td class="bdl">Omicron.</td>
+  <td class="bdl bdr">O short.</td>
+</tr>
+<tr>
+  <td class="bdl">&#916;</td>
+  <td class="bdl">&#948;</td>
+  <td class="bdl">Delta.</td>
+  <td class="bdl">D.</td>
+  <td class="bdl">&#928;</td>
+  <td class="bdl">&#960;</td>
+  <td class="bdl">Pi.</td>
+  <td class="bdl bdr">P.</td>
+</tr>
+<tr>
+  <td class="bdl">&#917;</td>
+  <td class="bdl">&#949;</td>
+  <td class="bdl">Epsilon.</td>
+  <td class="bdl">E short.</td>
+  <td class="bdl">&#929;</td>
+  <td class="bdl">&#961;</td>
+  <td class="bdl">Rho.</td>
+  <td class="bdl bdr">R.</td>
+</tr>
+<tr>
+  <td class="bdl">&#918;</td>
+  <td class="bdl">&#950;</td>
+  <td class="bdl">Zeta.</td>
+  <td class="bdl">Z.</td>
+  <td class="bdl">&#931;</td>
+  <td class="bdl">&#963;</td>
+  <td class="bdl">Sigma.</td>
+  <td class="bdl bdr">S.</td>
+</tr>
+<tr>
+  <td class="bdl">&#919;</td>
+  <td class="bdl">&#951;</td>
+  <td class="bdl">Eta.</td>
+  <td class="bdl">E long.</td>
+  <td class="bdl">&#932;</td>
+  <td class="bdl">&#964;</td>
+  <td class="bdl">Tau.</td>
+  <td class="bdl bdr">T.</td>
+</tr>
+<tr>
+  <td class="bdl">&#920;</td>
+  <td class="bdl">&#952;</td>
+  <td class="bdl">Theta.</td>
+  <td class="bdl">Th.</td>
+  <td class="bdl">&#933;</td>
+  <td class="bdl">&#965;</td>
+  <td class="bdl">Upsilon.</td>
+  <td class="bdl bdr">U.</td>
+</tr>
+<tr>
+  <td class="bdl">&#921;</td>
+  <td class="bdl">&#953;</td>
+  <td class="bdl">Iota.</td>
+  <td class="bdl">I.</td>
+  <td class="bdl">&#934;</td>
+  <td class="bdl">&#966;</td>
+  <td class="bdl">Phi.</td>
+  <td class="bdl bdr">F.</td>
+</tr>
+<tr>
+  <td class="bdl">&#922;</td>
+  <td class="bdl">&#954;</td>
+  <td class="bdl">Kappa.</td>
+  <td class="bdl">K.</td>
+  <td class="bdl">&#935;</td>
+  <td class="bdl">&#967;</td>
+  <td class="bdl">Chi.</td>
+  <td class="bdl bdr">Ch.</td>
+</tr>
+<tr>
+  <td class="bdl">&#923;</td>
+  <td class="bdl">&#955;</td>
+  <td class="bdl">Lambda.</td>
+  <td class="bdl">L.</td>
+  <td class="bdl">&#936;</td>
+  <td class="bdl">&#968;</td>
+  <td class="bdl">Psi.</td>
+  <td class="bdl bdr">Ps.</td>
+</tr>
+<tr>
+  <td class="bdb bdl">&#924;</td>
+  <td class="bdb bdl">&#956;</td>
+  <td class="bdb bdl">Mu.</td>
+  <td class="bdb bdl">M.</td>
+  <td class="bdb bdl">&#937;</td>
+  <td class="bdb bdl">&#969;</td>
+  <td class="bdb bdl">Omega.</td>
+  <td class="bdb bdl bdr">O long.</td>
+</tr>
+</table>
+
+<p class="caption3"><i>Roman numerals.</i></p>
+
+<table style="width:35em" summary="Roman Numerals">
+<tr>
+  <td class="bdt tdr">I</td>
+  <td class="bdt tdr2">1</td>
+  <td class="bdt bdl tdr">IX</td>
+  <td class="bdt tdr2">9</td>
+  <td class="bdt bdl tdr">LXX</td>
+  <td class="bdt tdr2">70</td>
+  <td class="bdt bdl tdr">D</td>
+  <td class="bdt tdr">500</td>
+</tr>
+<tr>
+  <td class="tdr">II</td>
+  <td class="tdr2">2</td>
+  <td class="bdl tdr">X</td>
+  <td class="tdr2">10</td>
+  <td class="bdl tdr">LXXX</td>
+  <td class="tdr2">80</td>
+  <td class="bdl tdr">DC</td>
+  <td class="tdr">600</td>
+</tr>
+<tr>
+  <td class="tdr">III</td>
+  <td class="tdr2">3</td>
+  <td class="bdl tdr">XIX</td>
+  <td class="tdr2">19</td>
+  <td class="bdl tdr">XC</td>
+  <td class="tdr2">90</td>
+  <td class="bdl tdr">DCC</td>
+  <td class="tdr">700</td>
+</tr>
+<tr>
+  <td class="tdr">IV</td>
+  <td class="tdr2">4</td>
+  <td class="bdl tdr">XX</td>
+  <td class="tdr2">20</td>
+  <td class="bdl tdr">C</td>
+  <td class="tdr2">100</td>
+  <td class="bdl tdr">DCCC</td>
+  <td class="tdr">800</td>
+</tr>
+<tr>
+  <td class="tdr">V</td>
+  <td class="tdr2">5</td>
+  <td class="bdl tdr">XXX</td>
+  <td class="tdr2">30</td>
+  <td class="bdl tdr">CL</td>
+  <td class="tdr2">150</td>
+  <td class="bdl tdr">CM</td>
+  <td class="tdr">900</td>
+</tr>
+<tr>
+  <td class="tdr">VI</td>
+  <td class="tdr2">6</td>
+  <td class="bdl tdr">XL</td>
+  <td class="tdr2">40</td>
+  <td class="bdl tdr">CC</td>
+  <td class="tdr2">200</td>
+  <td class="bdl tdr">M</td>
+  <td class="tdr">1000</td>
+</tr>
+<tr>
+  <td class="tdr">VII</td>
+  <td class="tdr2">7</td>
+  <td class="bdl tdr">L</td>
+  <td class="tdr2">50</td>
+  <td class="bdl tdr">CCC</td>
+  <td class="tdr2">300</td>
+  <td class="bdl tdr">MD</td>
+  <td class="tdr">1500</td>
+</tr>
+<tr>
+  <td class="bdb tdr">VIII</td>
+  <td class="bdb tdr2">8</td>
+  <td class="bdb bdl tdr">LX</td>
+  <td class="bdb tdr2">60</td>
+  <td class="bdb bdl tdr">CD</td>
+  <td class="bdb tdr2">400</td>
+  <td class="bdb bdl tdr">MCM</td>
+  <td class="bdb tdr">1900</td>
+</tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_94" id="Page_94">[94]</a></span></p>
+
+
+<p class="caption3">Mathematical signs.</p>
+
+<table style="width:35em" summary="Math Symbols">
+<tr>
+  <td class="bdt tdl2" style="width:20%">+</td>
+  <td class="bdt" style="width:40%">plus.</td>
+  <td class="bdt bdl tdl2" style="width:10%">~</td>
+  <td class="bdt" style="width:30%">difference</td>
+</tr>
+<tr>
+  <td class="tdl2">-</td>
+  <td>minus.</td>
+  <td class="bdl tdl2">&#8747;</td>
+  <td>integration.</td>
+</tr>
+<tr>
+  <td class="tdl2">&times;</td>
+  <td>multiplied by.</td>
+  <td class="bdl tdl2">&#8782;</td>
+  <td>equivalence.</td>
+</tr>
+<tr>
+  <td class="tdl2">&divide;</td>
+  <td>divided by.</td>
+  <td class="bdl tdl2">:</td>
+  <td>ratio.</td>
+</tr>
+<tr>
+  <td class="tdl2">=</td>
+  <td>equality.</td>
+  <td class="bdl tdl2">&#8762;</td>
+  <td>geometrical proportion.</td>
+</tr>
+<tr>
+  <td class="tdl2">&plusmn;</td>
+  <td>plus or minus.</td>
+  <td class="bdl tdl2">&ndash;:</td>
+  <td>difference, excess.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#9633;</td>
+  <td>square.</td>
+  <td class="bdl tdl2">&#8756;</td>
+  <td>therefore.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#9645;</td>
+  <td>rectangle.</td>
+  <td class="bdl tdl2">&#8757;</td>
+  <td>because.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#8710;</td>
+  <td>triangle.</td>
+  <td class="bdl tdl2">&#8734;</td>
+  <td>infinity.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#9711;</td>
+  <td>circle.</td>
+  <td class="bdl tdl2">&#8733;</td>
+  <td>varies as.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#8736;</td>
+  <td>angle.</td>
+  <td class="bdl tdl2">&#8730;</td>
+  <td>radical.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#8735;</td>
+  <td>right angle.</td>
+  <td class="bdl tdl2">&deg;</td>
+  <td>degree.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#10957; or &gt;</td>
+  <td>greater than.</td>
+  <td class="bdl tdl2">'</td>
+  <td>minute.</td>
+</tr>
+<tr>
+  <td class="tdl2">&#10958; or &lt;</td>
+  <td>less than.</td>
+  <td class="bdl tdl2">&quot;</td>
+  <td>second.</td>
+</tr>
+<tr>
+  <td class="bdb tdl2">&#8869;</td>
+  <td class="bdb">perpendicular.</td>
+  <td class="bdb bdl"></td>
+  <td class="bdb"></td>
+</tr>
+</table>
+
+<p class="caption2"><a name="NAMES_OF_ROCKS" id="NAMES_OF_ROCKS"></a>NAMES OF ROCKS.</p>
+
+
+<p>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 <a href="#Plate_III">Plate III</a>.</p>
+
+
+<p class="caption3"><i>Sedimentary material.</i></p>
+
+<p class="pmb2 center">[Including residual, detrital, eolian, glacial, organic, and chemically precipitated
+material.]</p>
+
+<table style="width:40em" summary="Metamorphic rocks">
+<tr>
+  <td class="vtop" style="width:18em">Agglomerate.<br />
+    Alabaster.<br />
+    Alluvium.<br />
+    Alum shale.<br />
+    Anhydrite.<br />
+    Apron (alluvial).<br />
+    Argillite.<br />
+    Arkose.<br />
+    Asphalt.<br />
+    Bench gravel.<br />
+    Bentonite.<br />
+    Boulder clay.<br />
+    Brea.<br />
+    Breccia.<br />
+    Brownstone.<br />
+    Burrstone.<br />
+    Calcarenite.<br />
+    Calc sinter.<br />
+    Caliche.<br />
+    Catlinite.<br />
+    Chalk.<br />
+    Chert.<br />
+    Clay.<br />
+    Coal.<br />
+    Conglomerate.<br />
+    Coprolite.<br />
+    Coquina.<br />
+    Detritus.<br />
+    Diatomaceous earth.<br />
+    Diluvium.<br />
+    Dolomite.<br />
+    Drift.<br />
+    Fan (alluvial).<br />
+    Fanglomerate.<br />
+    Flagstone.<br />
+    Flint.<br />
+    Freestone.<br />
+    Fuller's earth.<br />
+    Geyserite.<br />
+    Gravel.<br />
+    Graywacke.<br />
+    Greensand.<br />
+    Grit.<br />
+    Gumbo.<br />
+    Gypsum.<br />
+    Hardpan.<br />
+    Hematite.<br />
+    Infusorial earth.
+  </td>
+  <td class="vtop" style="width:18em">Ironstone (also igneous).<br />
+    Itacolumite.<br />
+    Kame.<br />
+    Kaolin.<br />
+    Laterite.<br />
+    Lignite.<br />
+    Limestone.<br />
+    Limonite.<br />
+    Loess.<br />
+    Marble (also metamorphic).<br />
+    Marl.<br />
+    Metaxite.<br />
+    Morainal deposit.<br />
+    Mudstone.<br />
+    Novaculite.<br />
+    Peat.<br />
+    Pelite.<br />
+    Phosphate rock.<br />
+    Phosphorite.<br />
+    Phthanite.<br />
+    Psammites.<br />
+    Psephites.<br />
+    Puddingstone.<br />
+    Pyroclastic material.<br />
+    Quartzite (also metamorphic).<br />
+    Reddle.<br />
+    Rock salt.<br />
+    Rock stream.<br />
+    Rubble.<br />
+    Salt.<br />
+    Sand.<br />
+    Sandstone.<br />
+    Selenite.<br />
+    Shale.<br />
+    Silt.<br />
+    Slate (also metamorphic).<br />
+    Soil.<br />
+    Stalactite.<br />
+    Stalagmite.<br />
+    Talc.<br />
+    Talus.<br />
+    Till.<br />
+    Travertine.<br />
+    Tripoli.<br />
+    Tufa (=chemically deposited lime).<br />
+    Tuff (=igneous fragments).<br />
+    Wacke.<br />
+    Wash.
+  </td>
+</tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_95" id="Page_95">[95]</a></span></p>
+
+
+<p class="caption3"><i>Metamorphic material.</i></p>
+
+<table style="width:40em" summary="Metamorphic rocks">
+<tr>
+  <td class="vtop" style="width:18em">Adinole.<br />
+    Amphibolite.<br />
+    Andalusite schist (?).<br />
+    Apo (rhyolite), etc.<br />
+    Argillite.<br />
+    Augen gneiss (also igneous).<br />
+    Biotite schist.<br />
+    Calc schist.<br />
+    Cataclastic.<br />
+    Chlorite schist
+    Clay slate.<br />
+    Damourite schist.<br />
+    Desmosite.<br />
+    Dynamometamorphic rock.<br />
+    Eclogite.<br />
+    Epidosite.<br />
+    Erlan.<br />
+    Erlanfels.<br />
+    Eulysite.<br />
+    Fibrolite schist
+    Garnet rock.<br />
+    Garnet schist.<br />
+    Gneiss.<br />
+    Granite gneiss.<br />
+    Graywacke (?).<br />
+    Green schists.<br />
+    Greenstone (also igneous).<br />
+    Greisen.<br />
+    Halleflinta.<br />
+    Hornblende schist
+    Hornfels.
+  </td>
+  <td class="vtop" style="width:18em">Hornstone.<br />
+    Itabirite.<br />
+    Kinzigite.<br />
+    Knotenschiefer.<br />
+    Knotty schists.<br />
+    Luxulianite (igneous?).<br />
+    Marble.<br />
+    Meta (diabase), etc.<br />
+    Mica schist.<br />
+    Mylonite.<br />
+    Ophicalcite.<br />
+    Ottrelite schist.<br />
+    Phyllite.<br />
+    Porcelanite.<br />
+    Protogene.<br />
+    Pyroschists.<br />
+    Quartz.<br />
+    Quartzite.<br />
+    Quartz schist.<br />
+    Schist.<br />
+    Sericite schist, etc.<br />
+    Serpentine.<br />
+    Slate.<br />
+    Soapstone.<br />
+    Sodalite.<br />
+    Spilosite.<br />
+    Steatite.<br />
+    Talc schist.<br />
+    Topazfels.<br />
+    Topaz rock.<br />
+    Zobtenite.
+  </td>
+</tr>
+</table>
+
+<p class="caption3"><i>Igneous material.</i></p>
+
+<table style="width:40em" summary="Igneous rocks">
+<tr>
+  <td class="vtop" style="width:18em">Absarokite.<br />
+    Abyssal.<br />
+    Adamellite.<br />
+    Adendiorite.<br />
+    Ailsyte.<br />
+    &Aring;kerite.<br />
+    Alaskite.<br />
+    Albitlte.<br />
+    Allivalite.<br />
+    Allochetite.<br />
+    Aln&ouml;lte.<br />
+    Alsbachite.<br />
+    Ambonite.<br />
+    Amherstite.<br />
+    Analcitite.<br />
+    Andesite.<br />
+    Anorthosite.<br />
+    Aphanitite.<br />
+    Aplite.<br />
+    Arkite.<br />
+    Atatschite.<br />
+    Augen gneiss (also metamorphic).<br />
+    Augitite.<br />
+    Avezacite.<br />
+    Banakite.<br />
+    Banatite.<br />
+    Bandaite.<br />
+    Basalt.<br />
+    Basanite.<br />
+    Beerbachite.<br />
+    Bekinkinite.<br />
+    Bombs.<br />
+    Borolanite.<br />
+    Bostonite.<br />
+    Camptonite.<br />
+    Carmeloite.<br />
+    Cascadite.<br />
+    Chibinite.<br />
+    Ciminite.<br />
+    Comendite.<br />
+    Complementary rocks.<br />
+    Coppaelite.<br />
+    Cortlandite.<br />
+    Cromaltite.<br />
+    Cumberlandite.<br />
+    Cuselite.<br />
+    Dacite.<br />
+    Dellenite.<br />
+    Diabase.<br />
+    Diallagite.<br />
+    Dike rock.<br />
+    Diorite.<br />
+    Ditroite.
+  </td>
+  <td class="vtop" style="width:18em">Dolerite.<br />
+    Dunite.<br />
+    Durbachite.<br />
+    Effusive rock.<br />
+    Ekerite.<br />
+    Elvan.<br />
+    Enstatite.<br />
+    Eruptive rock.<br />
+    Essexite.<br />
+    Estrellite.<br />
+    Eulysite.<br />
+    Extrusive rock.<br />
+    Farrisite.<br />
+    Felsite.<br />
+    Felsophyre.<br />
+    Fergusite.<br />
+    Fortunite.<br />
+    Fourchite.<br />
+    Foyaite.<br />
+    Gabbro.<br />
+    Gauteite.<br />
+    Garewaite.<br />
+    Glumarrite.<br />
+    Gladkaite.<br />
+    Granite.<br />
+    Granitite.<br />
+    Granitoid.<br />
+    Granodiorite.<br />
+    Granophyre.<br />
+    Greenstone (also metamorphic).<br />
+    Greisen (?).<br />
+    Grorudite.<br />
+    Harrisite.<br />
+    Harzburgite.<br />
+    Ha&uuml;ynophyre.<br />
+    Hawaiite.<br />
+    Hedrumite.<br />
+    Heumite.<br />
+    Holyokeite.<br />
+    Hornblendite.<br />
+    Hypabyssal rock.<br />
+    Hyperite.<br />
+    Hypersthenite.<br />
+    Ijolite.<br />
+    Intrusive rock.<br />
+    Irruptive (=Intrusive) rock.<br />
+    Isenite.<br />
+    Jacupirangite.<br />
+    Jumillite.<br />
+    Kaiwekite.<br />
+    Kedabekite.<br />
+    Kentallenite.<br />
+    Kenyite.
+  </td>
+</tr>
+</table>
+
+
+<p><span class="pagenum"><a name="Page_96" id="Page_96">[96]</a></span></p>
+
+<p class="caption3"><i>Igneous material.</i>&mdash;Continued.</p>
+
+<table style="width:40em" summary="Igneous rocks">
+<tr>
+  <td class="vtop" style="width:18em">Keratophyre.<br />
+    Kersantite.<br />
+    Kimberlite.<br />
+    Kobalaite.<br />
+    Krablite.<br />
+    Krager&ouml;ite.<br />
+    Kulaite.<br />
+    Kyschytymite.<br />
+    Lamprophyre.<br />
+    Latite.<br />
+    Laugenite.<br />
+    Laurdalite.<br />
+    Laurvikite.<br />
+    Lava.<br />
+    Lestiwarite.<br />
+    Leucite basalt.<br />
+    Leucite tephrite.<br />
+    Leucitite.<br />
+    Leucocratic.<br />
+    Lherzolite.<br />
+    Limbergite.<br />
+    Lindoite.<br />
+    Liparite.<br />
+    Litchfieldite.<br />
+    Lithoidite.<br />
+    Luciitss.<br />
+    Lujaurite.<br />
+    Madrupite.<br />
+    Maenaite.<br />
+    Magma basalt.<br />
+    Malchite.<br />
+    Malignite.<br />
+    Mangerite.<br />
+    Mariupolite.<br />
+    Melaphyre.<br />
+    Melilite basalt.<br />
+    Mesanite.<br />
+    Mica peridotite.<br />
+    Minette.<br />
+    Missourite.<br />
+    Monchiquite.<br />
+    Mondholdeite.<br />
+    Monmouthite.<br />
+    Monzonite.<br />
+    Mugearite.<br />
+    Naujaite.<br />
+    Nelsonite.<br />
+    Nephelinite.<br />
+    Nevadite.<br />
+    Nordmarkite.<br />
+    Norite.<br />
+    Obsidian.<br />
+    Odinite.<br />
+    Orbite.<br />
+    Orendite.<br />
+    Orn&ouml;ite.<br />
+    Orthophyre.<br />
+    Ortlerite.<br />
+    Ouachitite.<br />
+    Paisanite.<br />
+    Pantellerite.<br />
+    Pegmatite.<br />
+    Peridotite.<br />
+    Perknite.
+  </td>
+  <td class="vtop" style="width:18em">Perlite.<br />
+    Phanerite.<br />
+    Phonolite.<br />
+    Pierite.<br />
+    Pitchstone.<br />
+    Plagiaplite.<br />
+    Plagioclastic.<br />
+    Plumasite.<br />
+    Plutonic rock.<br />
+    Pollenite.<br />
+    Porphyry.<br />
+    Pulaskite.<br />
+    Pumice.<br />
+    Pyroxenite.<br />
+    Rhombenporphyry.<br />
+    Rhyolite.<br />
+    Rizzonite.<br />
+    Rockalite.<br />
+    Santorinite.<br />
+    Sanukite.<br />
+    Saxonite.<br />
+    Scyelite.<br />
+    Shastaite.<br />
+    Shonkinite.<br />
+    Shoshonite.<br />
+    Soda granite.<br />
+    S&ouml;lvsbergite.<br />
+    Sommaite.<br />
+    Spessartite.<br />
+    Sussexite.<br />
+    Syenite.<br />
+    Taimyrite.<br />
+    Tawite.<br />
+    Tephrite.<br />
+    Teschenite.<br />
+    Theralite.<br />
+    Tilaite.<br />
+    Tinguaite.<br />
+    Tjosite.<br />
+    Tonalite.<br />
+    Tonsbergite.<br />
+    Tordrillite.<br />
+    Toscanite (?).<br />
+    Trachy-andesite.<br />
+    Trachyte.<br />
+    Trap.<br />
+    Troctolite.<br />
+    Umptekite.<br />
+    Unakite.<br />
+    Ungaite.<br />
+    Urtite.<br />
+    Valbellite.<br />
+    Venanzite.<br />
+    Verite.<br />
+    Vitrophyre.<br />
+    Vogesite.<br />
+    Volcanic rock.<br />
+    Volhynite.<br />
+    Vulsinite.<br />
+    Websterite.<br />
+    Wehrlite.<br />
+    Windsorite.<br />
+    Wyomingite.<br />
+    Yamaskite.
+  </td>
+</tr>
+</table>
+
+
+<p><span class="pagenum"><a name="Page_97" id="Page_97">[97]</a><br />
+[98]<br />
+[99]</span></p>
+
+
+<p class="caption2"><a name="INDEX" id="INDEX"></a>INDEX.</p>
+
+<p class="center">[<a href="#alpha_A">A</a>] [<a href="#alpha_B">B</a>] [<a href="#alpha_C">C</a>] [<a href="#alpha_D">D</a>] [<a href="#alpha_E">E</a>] [<a href="#alpha_F">F</a>] [<a href="#alpha_G">G</a>] [<a href="#alpha_H">H</a>] [<a href="#alpha_I">I</a>] [<a href="#alpha_J">J</a>] [<a href="#alpha_L">L</a>]<br />
+[<a href="#alpha_M">M</a>] [<a href="#alpha_N">N</a>] [<a href="#alpha_O">O</a>] [<a href="#alpha_P">P</a>] [<a href="#alpha_R">R</a>] [<a href="#alpha_S">S</a>] [<a href="#alpha_T">T</a>] [<a href="#alpha_V">V</a>] [<a href="#alpha_W">W</a>] [<a href="#alpha_Z">Z</a>]</p>
+
+<p class="p0" style="margin-left: 25%">
+  <a name="alpha_A" id="alpha_A"></a><span class="alpha">A.</span><br />
+
+  Abbreviations, forms of.  <a href="#Page_55">55</a>-<a href="#Page_67">67</a><br />
+  Adhesive materials, choice.  <a href="#Page_37">37</a><br />
+  Alaska, maps of, reuse of.  <a href="#Page_17">17</a><br />
+  Albertype. <i>See</i> <a href="#Photogelatin_processes">Photogelatin processes</a>.<br />
+  Apparatus, photographs of, preferred to sketches.  <a href="#Page_29">29</a><br />
+  Approval of finished drawings, features to be covered by.  <a href="#Page_38">38</a><br />
+  <span class="ind2em">of</span> illustrations, regulations governing.  <a href="#Page_80">80</a><br />
+  Areas, patterns used to distinguish.  <a href="#Page_23">23</a><br />
+  <span class="ind2em">patterns</span> used to distinguish, plate showing.  <a href="#Page_62">62</a><br />
+  Army, Corps of Engineers of the, maps published by.  <a href="#Page_15">15</a><br />
+  Artotype. <i>See</i> <a href="#Photogelatin_processes">Photogelatin processes</a>.<br />
+  Atlases, published, use of.  <a href="#Page_15">15</a><br />
+  <br />
+
+  <a name="alpha_B" id="alpha_B"></a><span class="alpha">B.</span><br />
+
+  Base maps. <i>See</i> <a href="#Maps_base">Maps, base</a>.<br />
+  Bleaching photographic prints, method and solutions for.  <a href="#Page_69">69</a><br />
+  Border for maps, width and use of.  <a href="#Page_57">57</a>-<a href="#Page_58">58</a><br />
+  Bristol board, kind Mid sizes used.  <a href="#Page_24">24</a>, <a href="#Page_66">66</a><br />
+  Brash and pencil drawings, materials and methods used in making.  <a href="#Page_66">66</a>-<a href="#Page_67">67</a>, <a href="#Page_69">69</a><br />
+  Brushes, kinds and sizes used.  <a href="#Page_66">66</a>-<a href="#Page_67">67</a>,<a href="#Page_71">71</a><br />
+  <br />
+
+  <a name="alpha_C" id="alpha_C"></a><span class="alpha">C.</span><br />
+
+  Celluloid transferring, process of.  <a href="#Page_47">47</a><br />
+  <span class="ind2em">requisitions</span> for.  <a href="#Page_47">47</a><br />
+  Cerotype process, description and advantages of.  <a href="#Page_80">80</a>-<a href="#Page_81">81</a><br />
+  <a name="Changes" id="Changes"></a>Changes in engravings, possible kinds of.  <a href="#Page_38">38</a>-<a href="#Page_39">39</a>, <a href="#Page_90">90</a><br />
+  Changes in original material, draftsman to consult author on.  <a href="#Page_65">65</a><br />
+  Chemical elements, names and symbols of.  <a href="#Page_93">93</a><br />
+  Chromolithography, description of.  <a href="#Page_87">87</a>-<a href="#Page_80">80</a><br />
+  Civil divisions, lettering of.  <a href="#Page_53">53</a>, <a href="#Page_54">54</a><br />
+  Coal beds, indication of thickness of.  <a href="#Page_31">31</a><br />
+  Coast and Geodetic Survey charts, use of.  <a href="#Page_15">15</a><br />
+  Collotype. <i>See</i> <a href="#Photogelatin_processes">Photogelatin processes</a>.<br />
+  Coloring materials, use of.  <a href="#Page_26">26</a><br />
+  Colors, standard, for geologic maps.  <a href="#Page_62">62</a>-<a href="#Page_63">63</a><br />
+  <span class="ind2em">use</span> of, for ground-water features.  <a href="#Page_21">21</a>-<a href="#Page_23">23</a><br />
+  <span class="ind2em">on</span> original geologic maps.  <a href="#Page_27">27</a>-<a href="#Page_28">28</a><br />
+  Commas, form of.  <a href="#Page_54">54</a><br />
+  <span class="ind2em">use</span> of, in numbers.  <a href="#Page_54">54</a><br />
+  Contours, drawing of.  <a href="#Page_48">48</a>-<a href="#Page_50">50</a><br />
+  Cooperation, mention of.  <a href="#Page_13">13</a><br />
+  Copper, engraving on.  <a href="#Page_89">89</a>, <a href="#Page_90">90</a><br />
+  <span class="ind2em">etching</span> in relief on, process and advantages of.  <a href="#Page_75">75</a><br />
+  Copying methods of.  <a href="#Page_46">46</a>-<a href="#Page_48">48</a><br />
+  Corrections. <i>See</i> <a href="#Changes">Changes</a>.<br />
+  Cost of photo-engravings.  <a href="#Page_75">75</a>, <a href="#Page_78">78</a>, <a href="#Page_80">80</a>, <a href="#Page_81">81</a><br />
+  County maps, use of.  <a href="#Page_15">15</a><br />
+  Crayons, wax, use of.  <a href="#Page_26">26</a>, <a href="#Page_50">50</a>, <a href="#Page_51">51</a><br />
+  Credit for data of maps, indication of.  <a href="#Page_13">13</a><br />
+  Crystals, drawings of, making and lettering of.  <a href="#Page_70">70</a><br />
+  Cultural features, lettering of.  <a href="#Page_53">53</a>-<a href="#Page_54">54</a><br />
+  <span class="ind2em">list</span> of.  <a href="#Page_52">52</a>-<a href="#Page_53">53</a><br />
+  Curves, date showing.  <a href="#Page_64">64</a><br />
+  Cuts. <i>See</i> <a href="#Engravings">Engravings</a>.<br />
+  <br />
+
+  <a name="alpha_D" id="alpha_D"></a><span class="alpha">D.</span><br />
+
+  Details of a geologic map, plate showing.  <a href="#Page_58">58</a><br />
+  Diagrams, drawing and lettering of.  <a href="#Page_64">64</a><br />
+  <span class="ind2em">features</span> of, plate showing.  <a href="#Page_64">64</a><br />
+  <span class="ind2em">original</span>, general requirements for.  <a href="#Page_28">28</a>-<a href="#Page_20">20</a><br />
+  Director of the Survey, order by.  <a href="#Page_9">9</a><br />
+  Divisions of plates and figures, serial letters and numbers for.  <a href="#Page_12">12</a><br />
+  Drafting table, shadowless, description of.  <a href="#Page_47">47</a>-<a href="#Page_48">48</a><br />
+  <span class="ind2em">shadowless</span>, use of.  <a href="#Page_29">29</a>, <a href="#Page_48">48</a>, <a href="#Page_50">50</a><br />
+  Draftsmen, detail of, to aid author.  <a href="#Page_9">9</a><br />
+  <span class="ind2em">detail</span> of, to prepare base maps.  <a href="#Page_13">13</a>-<a href="#Page_14">14</a><br />
+  <span class="ind2em">experience</span> and reading required by.  <a href="#Page_41">41</a>-<a href="#Page_42">42</a><br />
+  <span class="ind2em">general</span> treatment of material by.  <a href="#Page_42">42</a>-<a href="#Page_43">43</a><br />
+  Drainage features, depiction of.  <a href="#Page_51">51</a>-<a href="#Page_52">52</a><br />
+  Drawing instruments, list of.  <a href="#Page_42">42</a><br />
+  Drawing materials, kinds used.  <a href="#Page_23">23</a>-<a href="#Page_26">26</a>, <a href="#Page_66">66</a>-<a href="#Page_67">67</a>, <a href="#Page_69">69</a>, <a href="#Page_71">71</a><br />
+  Drawings, authors', draftsmen may aid in making.  <a href="#Page_9">9</a><br />
+  <span class="ind2em">authors</span>', editorial revision of.  <a href="#Page_38">38</a><br />
+  <span class="ind2em">finished</span>, general requirements for.  <a href="#Page_41">41</a>-<a href="#Page_42">42</a><br />
+  <span class="ind3em">requests</span> for photographs of.  <a href="#Page_34">34</a><br />
+  Duplicates of engravings, charges for.  <a href="#Page_38">38</a><br />
+  <br />
+
+  <a name="alpha_E" id="alpha_E"></a><span class="alpha">E.</span><br />
+
+  Effectiveness of illustrations, elements that produce.  <a href="#Page_7">7</a>, <a href="#Page_30">30</a><br />
+  Electrotypes of engravings, charges for.  <a href="#Page_38">38</a><br />
+  Elements, chemical, names and symbols of.  <a href="#Page_93">93</a><br />
+  <a name="Engraving_on_stone" id="Engraving_on_stone"></a>Engraving on stone, process of.  <a href="#Page_89">89</a>-<a href="#Page_90">90</a><br />
+  <span class="ind2em"><i>See also</i> <a href="#Lithography2">Lithography</a>.</span><br />
+  <a name="Engravings" id="Engravings"></a>Engravings, changes in.  <a href="#Page_38">38</a>-<a href="#Page_39">39</a><br />
+  <span class="ind2em">original</span>, time of keeping.  <a href="#Page_37">37</a><br />
+  Erasers, injury to paper by.  <a href="#Page_67">67</a><br />
+  <span class="ind2em">kinds</span> used.  <a href="#Page_25">25</a>, <a href="#Page_67">67</a>-<a href="#Page_68">68</a><br />
+  Erasures, smoothing paper after.  <a href="#Page_68">68</a><br />
+  Explanations on maps, arrangement and lettering of.  <a href="#Page_19">19</a>, <a href="#Page_58">58</a>-<a href="#Page_50">50</a><br />
+  <br />
+
+  <a name="alpha_F" id="alpha_F"></a><span class="alpha">F.</span><br />
+
+  Figures, differences from plates.  <a href="#Page_10">10</a>-<a href="#Page_11">11</a><br />
+  <span class="ind2em">divisions</span> of, serial letters for.  <a href="#Page_12">12</a><br />
+  <span class="ind2em">methods</span> of inserting, plate showing.  <a href="#Page_12">12</a><br />
+  Formations, geologic, use of letter symbols for.  <a href="#Page_20">20</a>-<a href="#Page_21">21</a><br />
+  Fossils. <i>See</i> <a href="#Specimens">Specimens</a>.<br />
+  Four-color process, advantage of.  <a href="#Page_80">80</a><br />
+  <br />
+
+  <a name="alpha_G" id="alpha_G"></a><span class="alpha">G.</span><br />
+
+  Gas wells, symbols for.  <a href="#Page_21">21</a><br />
+  Generalization, true, meaning of.  <a href="#Page_17">17</a><br />
+  Geographic tables and formulas (Bull. 650), use of.  <a href="#Page_44">44</a>, <a href="#Page_45">45</a><br />
+  Geologic periods of time, names of.  <a href="#Page_92">92</a><br />
+  Gouache, use of.  <a href="#Page_67">67</a>, <a href="#Page_69">69</a><br />
+  Great Lakes surveys, maps published by.  <a href="#Page_15">15</a><br />
+<span class="pagenum"><a name="Page_100" id="Page_100">[100]</a></span>
+  Greek letters, forms, names, and English sounds of.  <a href="#Page_93">93</a><br />
+  Ground-water features, symbols representing.  <a href="#Page_21">21</a>-<a href="#Page_23">23</a><br />
+  <br />
+
+  <a name="alpha_H" id="alpha_H"></a><span class="alpha">H.</span><br />
+
+  Hachuring, use of.  <a href="#Page_50">50</a><br />
+  Half-tone engraving, preparation of copy for.  <a href="#Page_77">77</a>-<a href="#Page_78">78</a><br />
+  <span class="ind2em">process</span> and advantages of.  <a href="#Page_75">75</a>-<a href="#Page_78">78</a><br />
+  <span class="ind2em">three</span>-color process of.  <a href="#Page_78">78</a>-<a href="#Page_80">80</a><br />
+  Half tones, changes in.  <a href="#Page_39">39</a><br />
+  <span class="ind2em">prints</span> of, showing effects produced by different screens.  <a href="#Page_56">56</a><br />
+  <span class="ind2em">requirements</span> for printing.  <a href="#Page_11">11</a><br />
+  Heliotype. <i>See</i> <a href="#Photogelatin_processes">Photogelatin processes</a>.<br />
+  Hill shading, use of.  <a href="#Page_60">60</a>-<a href="#Page_51">51</a><br />
+  Hydrographic features, lettering of.  <a href="#Page_54">54</a><br />
+  <span class="ind2em">representation</span> of.  <a href="#Page_51">51</a>-<a href="#Page_52">52</a><br />
+  Hypsographic features, lettering of.  <a href="#Page_54">54</a><br />
+  <br />
+
+  <a name="alpha_I" id="alpha_I"></a><span class="alpha">I.</span><br />
+
+  Illustrations, kinds of.  <a href="#Page_10">10</a>-<a href="#Page_11">11</a><br />
+  Inks, kinds used.  <a href="#Page_25">25</a>, <a href="#Page_67">67</a><br />
+  <span class="ind2em">methods</span> of using.  <a href="#Page_25">25</a><br />
+  Inserting plates and figures, methods of, plate showing.  <a href="#Page_12">12</a><br />
+  Instruments, draftsmen's, list of.  <a href="#Page_42">42</a><br />
+  <br />
+
+  <a name="alpha_J" id="alpha_J"></a><span class="alpha">J.</span><br />
+
+  Japanese transparent water colors, use of.  <a href="#Page_26">26</a><br />
+  <br />
+
+  <a name="alpha_L" id="alpha_L"></a><span class="alpha">L.</span><br />
+
+  Land Office maps, scales and detail of.  <a href="#Page_14">14</a>-<a href="#Page_15">15</a><br />
+  Latitude, length of 1&deg; of, at intervals of 10&deg;.  <a href="#Page_91">91</a><br />
+  Lending of photographs and drawings, rules governing.  <a href="#Page_34">34</a><br />
+  Letter symbols, use of, on geologic maps.  <a href="#Page_20">20</a>-<a href="#Page_21">21</a><br />
+  Lettering, directions for.  <a href="#Page_53">53</a>-<a href="#Page_55">55</a><br />
+  <span class="ind2em">for</span> lithographing.  <a href="#Page_90">90</a><br />
+  <span class="ind2em">for</span> names of streams.  <a href="#Page_52">52</a>, <a href="#Page_54">54</a><br />
+  <span class="ind2em">on</span> diagrams.  <a href="#Page_64">64</a><br />
+  <span class="ind2em">on</span> drawings of crystals.  <a href="#Page_70">70</a><br />
+  <span class="ind2em">on</span> original maps.  <a href="#Page_19">19</a><br />
+  <span class="ind2em">on</span> plans and cross sections of mines.  <a href="#Page_65">65</a>-<a href="#Page_66">66</a><br />
+  <span class="ind2em">reduction</span> sheet used in, plate showing.  <a href="#Page_54">54</a><br />
+  <span class="ind2em">use</span> of type for.  <a href="#Page_54">54</a>-<a href="#Page_55">55</a><br />
+  Light, direction and gradation of.  <a href="#Page_66">66</a><br />
+  Lithographs, printing and insertion of.  <a href="#Page_11">11</a><br />
+  <a name="Lithography2" id="Lithography2"></a>Lithography, original process of.  <a href="#Page_83">83</a>-<a href="#Page_85">85</a><br />
+  <span class="ind2em"><i>See also</i> <a href="#Engraving_on_stone">Engraving on stone</a>.</span><br />
+  Longitude, length of 1&deg; of, at latitudes 0&deg; to 90&deg;.  <a href="#Page_91">91</a><br />
+  <br />
+
+  <a name="alpha_M" id="alpha_M"></a><span class="alpha">M.</span><br />
+
+  Map of the world, millionth-scale, use of, for base maps.  <a href="#Page_14">14</a><br />
+  Maps, areal patterns for, drawing of.  <a href="#Page_61">61</a>-<a href="#Page_62">62</a><br />
+  <span class="ind2em">bar</span> scales for.  <a href="#Page_59">59</a>-<a href="#Page_60">60</a><br />
+  <span class="ind2em"><a name="Maps_base" id="Maps_base"></a>base</span>, conventional symbols used on. <a href="#Page_45">45</a>-<a href="#Page_46">46</a><br />
+  <span class="ind3em">including</span> new data, how obtained.  <a href="#Page_13">13</a>-<a href="#Page_14">14</a><br />
+  <span class="ind3em">indication</span> of sources on.  <a href="#Page_13">13</a><br />
+  <span class="ind3em">of</span> the United States on small scales, use of.  <a href="#Page_15">15</a><br />
+  <span class="ind3em">published</span> maps available for.  <a href="#Page_14">14</a>-<a href="#Page_17">17</a><br />
+  <span class="ind3em">reuse</span> of, to be approved.  <a href="#Page_13">13</a><br />
+  <span class="ind2em">black</span> and whits, patterns used on, plate showing.  <a href="#Page_62">62</a><br />
+  <span class="ind2em">borders</span> for.  <a href="#Page_57">57</a>-<a href="#Page_68">68</a><br />
+  <span class="ind2em">cultural</span> features on.  <a href="#Page_52">52</a>-<a href="#Page_53">53</a><br />
+  <span class="ind2em">enlargement</span> and reduction of.  <a href="#Page_18">18</a><br />
+  <span class="ind2em">explanations</span> for.  <a href="#Page_19">19</a>, <a href="#Page_58">58</a>-<a href="#Page_59">59</a><br />
+  <span class="ind2em">geologic</span>, details of, plate showing.  <a href="#Page_58">58</a><br />
+  <span class="ind2em">printing</span> of.  <a href="#Page_87">87</a>-<a href="#Page_89">89</a><br />
+  <span class="ind2em">standard</span> colors for.  <a href="#Page_62">62</a>-<a href="#Page_63">63</a><br />
+  <span class="ind2em">hydrographic</span> features on.  <a href="#Page_61">61</a>-<a href="#Page_52">52</a><br />
+  <span class="ind2em">lettering</span> on.  <a href="#Page_53">53</a>-<a href="#Page_65">65</a><br />
+  <span class="ind2em">materials</span> used for drawing.  <a href="#Page_23">23</a>-<a href="#Page_28">28</a><br />
+  <span class="ind2em">orientation</span> of.  <a href="#Page_18">18</a><br />
+  <span class="ind2em">original</span>, margin required on.  <a href="#Page_19">19</a><br />
+  <span class="ind2em">original</span> base, amount of detail on.  <a href="#Page_17">17</a><br />
+  <span class="ind2em">must</span> be free from colors and symbols.  <a href="#Page_28">28</a><br />
+  <span class="ind2em">preparation</span> of.  <a href="#Page_13">13</a>-<a href="#Page_14">14</a>, <a href="#Page_17">17</a>-<a href="#Page_18">18</a><br />
+  <span class="ind2em">original</span> geologic, method of coloring.  <a href="#Page_27">27</a>-<a href="#Page_28">28</a><br />
+  <span class="ind2em">projection</span> for.  <a href="#Page_18">18</a>-<a href="#Page_19">19</a>, <a href="#Page_43">43</a>-<a href="#Page_45">45</a><br />
+  <span class="ind2em">reduction</span> or enlargement of, marking for.  <a href="#Page_63">63</a>-<a href="#Page_64">64</a><br />
+  <span class="ind2em">relief</span> on.  <a href="#Page_48">48</a>-<a href="#Page_51">51</a><br />
+  <span class="ind2em">standard</span> scales for.  <a href="#Page_18">18</a><br />
+  <span class="ind2em">symbols</span> used on.  <a href="#Page_20">20</a>-<a href="#Page_23">23</a><br />
+  <span class="ind3em">drawing</span> of.  <a href="#Page_61">61</a><br />
+  <span class="ind3em">plates</span> showing.  <a href="#Page_20">20</a>, <a href="#Page_46">46</a><br />
+  <span class="ind2em">titles</span> for.  <a href="#Page_58">58</a><br />
+  <span class="ind2em">topographic</span>, scales of.  <a href="#Page_14">14</a>-<a href="#Page_15">15</a><br />
+  Mathematical signs, forms and names of.  <a href="#Page_94">94</a><br />
+  Measures, linear, metric equivalents of.  <a href="#Page_92">92</a><br />
+  Measuring scales for map projection, use of.  <a href="#Page_44">44</a><br />
+  Meridians used on public-land maps, diagram showing.  <a href="#Page_16">16</a><br />
+  Metric measures, English equivalents of.  <a href="#Page_92">92</a><br />
+  Millionth-scale map, use of.  <a href="#Page_14">14</a><br />
+  Mine plans, conventional lines for.  <a href="#Page_29">29</a><br />
+  <span class="ind2em">features</span> of.  <a href="#Page_65">65</a>-<a href="#Page_66">66</a><br />
+  <span class="ind2em">symbols</span> used on, plate showing.  <a href="#Page_20">20</a><br />
+  Minerals. <i>See</i> <a href="#Rocks">Rocks</a>.<br />
+  Mississippi River Commission, maps published by <a href="#Page_15">15</a><br />
+  <br />
+
+  <a name="alpha_N" id="alpha_N"></a><span class="alpha">N.</span><br />
+
+  Names of rocks.  <a href="#Page_94">94</a>-<a href="#Page_97">97</a><br />
+  National forest maps and proclamations, use of.  <a href="#Page_15">15</a><br />
+  <br />
+
+  <a name="alpha_O" id="alpha_O"></a><span class="alpha">O.</span><br />
+
+  Offset process, description of.  <a href="#Page_87">87</a><br />
+  Oilwells, symbols for.  <a href="#Page_21">21</a><br />
+  Opaquing, meaning of.  <a href="#Page_18">18</a>, <a href="#Page_47">47</a>, <a href="#Page_86">86</a><br />
+  Orientation of maps, requirements for.  <a href="#Page_18">18</a><br />
+  Original drawings, general treatment of, by draftsmen.  <a href="#Page_42">42</a>-<a href="#Page_43">43</a><br />
+  <span class="ind2em">preparation</span> of.  <a href="#Page_12">12</a>-<a href="#Page_40">40</a><br />
+  Outdoor sketches, redrawing of.  <a href="#Page_69">69</a>-<a href="#Page_70">70</a><br />
+  <br />
+
+  <a name="alpha_P" id="alpha_P"></a><span class="alpha">P.</span><br />
+
+  Panoramas, construction of.  <a href="#Page_71">71</a><br />
+  Paper, kinds used for drawings.  <a href="#Page_23">23</a>-<a href="#Page_24">24</a>, <a href="#Page_60">60</a>, <a href="#Page_61">61</a>, <a href="#Page_66">66</a>, <a href="#Page_69">69</a><br />
+  Pastes, use of.  <a href="#Page_37">37</a><br />
+  Patterns, areal, method of drawing.  <a href="#Page_61">61</a>-<a href="#Page_62">62</a><br />
+  <span class="ind2em">areal</span>, plate showing.  <a href="#Page_62">62</a><br />
+  Pen drawings, materials and methods used in making.  <a href="#Page_67">67</a>-<a href="#Page_68">68</a>, <a href="#Page_68">68</a>-<a href="#Page_69">69</a><br />
+  Pencils, colored, use of.  <a href="#Page_26">26</a><br />
+  <span class="ind2em">drawing</span>, quality and grades of.  <a href="#Page_25">25</a>, <a href="#Page_66">66</a><br />
+  Pens, kinds of, used for drawing.  <a href="#Page_25">25</a>, <a href="#Page_48">48</a>, <a href="#Page_67">67</a><br />
+  Photoengraving, cost of.  <a href="#Page_75">75</a>, <a href="#Page_78">78</a>, <a href="#Page_80">80</a>, <a href="#Page_81">81</a><br />
+  <span class="ind2em">general</span> features of.  <a href="#Page_72">72</a>-<a href="#Page_73">73</a><br />
+  Photoengravings, printing and insertion of.  <a href="#Page_11">11</a><br />
+  <a name="Photogelatin_processes" id="Photogelatin_processes"></a>Photogelatin processes, description of.  <a href="#Page_82">82</a>-<a href="#Page_83">83</a><br />
+<span class="pagenum"><a name="Page_101" id="Page_101">[101]</a></span>
+  Photographs, adaptation of.  <a href="#Page_83">83</a><br />
+  <span class="ind2em">bleaching</span> of.  <a href="#Page_69">69</a><br />
+  <span class="ind2em">care</span> needed in taking and handling.  <a href="#Page_32">32</a>, <a href="#Page_33">33</a>, <a href="#Page_39">39</a>-<a href="#Page_40">40</a><br />
+  <span class="ind2em">copyrighted</span>, consent for use of.  <a href="#Page_33">33</a>-<a href="#Page_34">34</a><br />
+  <span class="ind2em">duplicate</span> prints of, requests for.  <a href="#Page_34">34</a><br />
+  <span class="ind2em">mounting</span> and numbering of.  <a href="#Page_33">33</a>, <a href="#Page_36">36</a>-<a href="#Page_37">37</a><br />
+  <span class="ind2em">poor</span>, mating of drawings over.  <a href="#Page_68">68</a>-<a href="#Page_69">69</a><br />
+  <span class="ind2em">preparation</span> of, for half-tone engraving.  <a href="#Page_77">77</a>-<a href="#Page_78">78</a><br />
+  <span class="ind2em">record</span> of source of.  <a href="#Page_34">34</a><br />
+  <span class="ind2em">selection</span> of.  <a href="#Page_32">32</a>-<a href="#Page_33">33</a><br />
+  <span class="ind2em">retouching</span> of.  <a href="#Page_68">68</a>, <a href="#Page_70">70</a>-<a href="#Page_71">71</a><br />
+  <span class="ind2em">suitability</span> of. <a href="#Page_9">9</a><br />
+  <span class="ind2em">unpublished</span>, issue and use of.  <a href="#Page_34">34</a><br />
+  Photolithographs, changes in.  <a href="#Page_39">39</a><br />
+  Photolithography, description of.  <a href="#Page_86">86</a>-<a href="#Page_87">87</a><br />
+  Planographic process, description of.  <a href="#Page_87">87</a><br />
+  Plans of mines, drawing and lettering of.  <a href="#Page_29">29</a>, <a href="#Page_65">65</a>-<a href="#Page_66">66</a><br />
+  <span class="ind2em">symbols</span> used on, plate showing.  <a href="#Page_20">20</a><br />
+  Plates, differences from figures.  <a href="#Page_10">10</a>-<a href="#Page_11">11</a><br />
+  <span class="ind2em">divisions</span> of, serial letters and numbers for.  <a href="#Page_12">12</a><br />
+  <span class="ind2em">grouping</span> small illustrations on.  <a href="#Page_36">36</a>-<a href="#Page_37">37</a><br />
+  <span class="ind2em">methods</span> of inserting, plate showing.  <a href="#Page_12">12</a><br />
+  Political divisions, lettering of.  <a href="#Page_53">53</a>, <a href="#Page_54">54</a><br />
+  Post-route maps, scales and detail of.  <a href="#Page_15">15</a><br />
+  Projection for maps, preparation and checking of. <a href="#Page_18">18</a>-<a href="#Page_19">19</a>, <a href="#Page_43">43</a>-<a href="#Page_45">45</a><br />
+  Proofs, changes in.  <a href="#Page_76">76</a><br />
+  <span class="ind2em">correction</span> of.  <a href="#Page_38">38</a>-<a href="#Page_39">39</a><br />
+  <span class="ind2em">duplicate</span>, supplying of.  <a href="#Page_30">30</a><br />
+  <span class="ind2em">submittal</span> of.  <a href="#Page_38">38</a><br />
+  Public-land maps, meridians, parallels, and township lines used on, diagram showing.  <a href="#Page_16">16</a><br />
+  Public works, lettering of.  <a href="#Page_53">53</a><br />
+  Punctuation marks, forms of.  <a href="#Page_54">54</a><br />
+  Purpose of illustrations in Survey reports.  <a href="#Page_8">8</a>, <a href="#Page_40">40</a><br />
+  <br />
+
+  <a name="alpha_R" id="alpha_R"></a><span class="alpha">R.</span><br />
+
+  Railroad surveys, data for maps obtainable from.  <a href="#Page_15">15</a><br />
+  Railroads, names of, on maps.  <a href="#Page_57">57</a><br />
+  Reduction of maps, marking drawings for.  <a href="#Page_63">63</a>-<a href="#Page_64">64</a><br />
+  <span class="ind2em">means</span> of.  <a href="#Page_18">18</a><br />
+  Reduction sheet for lettering, plate showing.  <a href="#Page_54">54</a><br />
+  <span class="ind2em">use</span> of.  <a href="#Page_55">55</a><br />
+  Relief, methods of expressing.  <a href="#Page_48">48</a>-<a href="#Page_51">51</a><br />
+  Reproduction of illustrations, processes for.  <a href="#Page_72">72</a>-<a href="#Page_90">90</a><br />
+  <span class="ind2em">relation</span> of, to the drawing supplied.  <a href="#Page_7">7</a>, <a href="#Page_40">40</a><br />
+  Reticulation, sketching by.  <a href="#Page_47">47</a><br />
+  Retouching of photographs, materials and method used in.  <a href="#Page_68">68</a>, <a href="#Page_70">70</a>-<a href="#Page_71">71</a><br />
+  Reuse of illustrations, procedure for.  <a href="#Page_37">37</a>-<a href="#Page_38">38</a><br />
+  <a name="Rocks" id="Rocks"></a>Rocks, igneous, names of.  <a href="#Page_95">95</a>-<a href="#Page_97">97</a><br />
+  <span class="ind2em">metamorphic</span>, names of.  <a href="#Page_95">95</a><br />
+  <span class="ind2em">sedimentary</span>, names of.  <a href="#Page_94">94</a>-<a href="#Page_95">95</a><br />
+  <span class="ind2em">symbols</span> used to distinguish.  <a href="#Page_32">32</a><br />
+  <span class="ind2em"><i>See also</i> <a href="#Specimens">Specimens</a>.</span><br />
+  Roman numerals, numbers expressed by.  <a href="#Page_93">93</a><br />
+  Rubber, liquid, use of.  <a href="#Page_37">37</a><br />
+  <br />
+
+  <a name="alpha_S" id="alpha_S"></a><span class="alpha">S.</span><br />
+
+  Scales, bar, forms of.  <a href="#Page_50">50</a>-<a href="#Page_60">60</a><br />
+  <span class="ind2em">measuring</span> for projection of maps.  <a href="#Page_44">44</a><br />
+  <span class="ind2em">standard</span>, of maps.  <a href="#Page_18">18</a><br />
+  Scope of this manual.  <a href="#Page_7">7</a><br />
+  Screens, half-tone prints showing effects produced by.  <a href="#Page_56">56</a><br />
+  Selection of illustrations, considerations governing.  <a href="#Page_8">8</a>-<a href="#Page_9">9</a><br />
+  Sections, columnar, original drawings for.  <a href="#Page_31">31</a><br />
+  <span class="ind2em">columnar</span>, symbols used in, plate showing.  <a href="#Page_32">32</a><br />
+  <span class="ind2em">structure</span>, combination of, with views of topography.  <a href="#Page_30">30</a>-<a href="#Page_31">31</a><br />
+  <span class="ind3em">drawing</span> of.  <a href="#Page_64">64</a>-<a href="#Page_65">65</a><br />
+  <span class="ind3em">original</span> drawings for.  <a href="#Page_29">29</a>-<a href="#Page_31">31</a><br />
+  <span class="ind3em">symbols</span> used in, plate showing.  <a href="#Page_32">32</a><br />
+  <span class="ind3em">vertical</span> exaggeration of.  <a href="#Page_30">30</a><br />
+  Shading, kinds used.  <a href="#Page_67">67</a><br />
+  Signs, mathematical, forms and names of.  <a href="#Page_94">94</a><br />
+  Sises of illustrations.  <a href="#Page_11">11</a>-<a href="#Page_12">12</a>, <a href="#Page_40">40</a><br />
+  <a name="Specimens" id="Specimens"></a>Specimens, borrowed and fragile, care of.  <a href="#Page_35">35</a><br />
+  <span class="ind2em">drawings</span> of, methods of making.  <a href="#Page_60">60</a>-<a href="#Page_68">68</a><br />
+  <span class="ind2em">paleontologic</span>, transmittal of.  <a href="#Page_35">35</a><br />
+  <span class="ind2em">photographs</span> of, how printed.  <a href="#Page_68">68</a><br />
+  <span class="ind3em">how</span> used.  <a href="#Page_34">34</a>-<a href="#Page_85">85</a><br />
+  Springs, symbols for.  <a href="#Page_22">22</a>, <a href="#Page_23">23</a><br />
+  State maps, use of.  <a href="#Page_15">15</a><br />
+  Stipple, production of.  <a href="#Page_50">50</a>, <a href="#Page_51">51</a><br />
+  Stone, engraving on.  <a href="#Page_89">89</a>-<a href="#Page_90">90</a><br />
+  Streams, drawing of.  <a href="#Page_51">51</a>-<a href="#Page_52">52</a><br />
+  <span class="ind2em">lettering</span> names of.  <a href="#Page_52">52</a><br />
+  Submittal of illustrations.  <a href="#Page_10">10</a><br />
+  Symbols, drawing of.  <a href="#Page_20">20</a>, <a href="#Page_61">61</a><br />
+  <span class="ind2em">for</span> ground-water features, uniformity needed in.  <a href="#Page_21">21</a>-<a href="#Page_23">23</a><br />
+  <span class="ind2em">for</span> maps and mine plans, plates showing.  <a href="#Page_20">20</a>, <a href="#Page_46">46</a><br />
+  <span class="ind2em">uniform</span> use of.  <a href="#Page_20">20</a>, <a href="#Page_45">45</a>-<a href="#Page_46">46</a><br />
+  <span class="ind2em">for</span> oil and gas wells, features of.  <a href="#Page_21">21</a><br />
+  <span class="ind2em">for</span> structure and columnar sections, plate showing.  <a href="#Page_32">32</a><br />
+  <span class="ind2em">lithologic</span>, use of.  <a href="#Page_32">32</a><br />
+  <br />
+
+  <a name="alpha_T" id="alpha_T"></a><span class="alpha">T.</span><br />
+
+  Three-color half-tones, process of making.  <a href="#Page_78">78</a>-<a href="#Page_80">80</a><br />
+  Titles of illustrations, arrangement and place of.  <a href="#Page_58">58</a><br />
+  <span class="ind2em">printing</span> of.  <a href="#Page_19">19</a>-<a href="#Page_20">20</a><br />
+  <span class="ind2em">wording</span> and lettering of.  <a href="#Page_19">19</a><br />
+  Tooling on half-tones, effects obtained by.  <a href="#Page_77">77</a>, <a href="#Page_78">78</a><br />
+  Topographic atlas sheets, scales of.  <a href="#Page_14">14</a><br />
+  Tracing, method of.  <a href="#Page_46">46</a>-<a href="#Page_47">47</a><br />
+  <span class="ind2em">use</span> of colors in.  <a href="#Page_46">46</a>-<a href="#Page_47">47</a><br />
+  Tracing linen, use of.  <a href="#Page_24">24</a>-<a href="#Page_25">25</a><br />
+  Transferring, celluloid, process of.  <a href="#Page_47">47</a><br />
+  <span class="ind2em">celluloid</span>, requisitions for.  <a href="#Page_47">47</a><br />
+  Type, lettering with.  <a href="#Page_54">54</a>-<a href="#Page_55">55</a><br />
+  <span class="ind2em">styles</span> and sizes of.  <a href="#Page_55">55</a><br />
+  <br />
+
+  <a name="alpha_V" id="alpha_V"></a><span class="alpha">V.</span><br />
+
+  Value of illustrations in Survey reports.  <a href="#Page_8">8</a><br />
+  Vara, length of.  <a href="#Page_92">92</a><br />
+  Vignetting, effect obtained by.  <a href="#Page_78">78</a><br />
+  <br />
+
+  <a name="alpha_W" id="alpha_W"></a><span class="alpha">W.</span><br />
+
+  Wall map of the United States, use of, for basemaps.  <a href="#Page_14">14</a><br />
+  Water colors, use of.  <a href="#Page_26">26</a>, <a href="#Page_67">67</a>, <a href="#Page_71">71</a><br />
+  Waterlining, use of.  <a href="#Page_52">52</a><br />
+  Wax engraving, process and advantages of.  <a href="#Page_80">80</a>-<a href="#Page_81">81</a><br />
+  Wells, symbols for.  <a href="#Page_22">22</a>, <a href="#Page_23">23</a><br />
+  Wood engraving, process of.  <a href="#Page_81">81</a>-<a href="#Page_82">82</a><br />
+  <br />
+
+  <a name="alpha_Z" id="alpha_Z"></a><span class="alpha">Z.</span><br />
+
+  Zinc etchings, changes in.  <a href="#Page_38">38</a>-<a href="#Page_39">39</a><br />
+  <span class="ind2em">drawings</span> for.  <a href="#Page_74">74</a><br />
+  <span class="ind2em">insertion</span> of.  <a href="#Page_11">11</a><br />
+  <span class="ind2em">making</span> and advantages of.  <a href="#Page_73">73</a>-<a href="#Page_75">75</a><br />
+</p>
+
+<p class="center">&#9711;</p>
+
+
+<hr class="tb" />
+
+<div class="trans_notes">
+<p class="caption2">Transcriber's Note</p>
+
+<p>Paragraphs split by illustrations were rejoined.</p>
+
+<p>In the table of Mathematical symbols, the symbol for "varies as" was
+set to the unicode symbol for "proportional to" (&amp;#8733; = &#8733;).</p>
+</div>
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of The Preparation of Illustrations for
+Reports of the United States Geologi, by John L. Ridgway
+
+*** END OF THIS PROJECT GUTENBERG EBOOK THE PREPARATION OF ILLUSTRATIONS ***
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+</body>
+</html>
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+The Project Gutenberg EBook of The Preparation of Illustrations for
+Reports of the United States Geological Survey, by John L. Ridgway
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org/license
+
+
+Title: The Preparation of Illustrations for Reports of the United States Geological Survey
+       With Brief Descriptions of Processes of Reproduction
+
+Author: John L. Ridgway
+
+Release Date: July 16, 2013 [EBook #43232]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE PREPARATION OF ILLUSTRATIONS ***
+
+
+
+
+Produced by Tom Cosmas from materials scanned in and
+obtained from The Internet Archive.
+
+
+
+
+
+
+
+
+
+
+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 deg. 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 deg. of
+longitude and 4 deg. 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 deg..
+   Pens, double-pointed.              *Triangle, 60 deg..
+  *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 deg. 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 deg. apart and
+dividing by 2.
+
+The distance between parallels that are 2 deg. apart, as shown in the
+diagram, may be computed from Table 6 of "Geographic tables and
+formulas," as follows:
+
+                                   Meters.         Meters.
+
+1 deg. of latitude on 37th parallel = 100,975.1 / 2 =  55,487.5
+1 deg. of latitude on 36th parallel                 = 110,956.2
+1 deg. of latitude on 35th parallel = 110,937.6 / 2 =  55,468.8
+                                                  ---------
+True distance from 35 deg. to 37 deg. 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.
+
+  L 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 deg. 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 deg. 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 deg. 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 deg. 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 deg. 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 deg. 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.
+  x   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.           deg.   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.
+  Akerite.                           Elvan.
+  Alaskite.                          Enstatite.
+  Albitlte.                          Eruptive rock.
+  Allivalite.                        Essexite.
+  Allochetite.                       Estrellite.
+  Alnoelte.                           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.                        Haueynophyre.
+  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.
+  Krageroeite.                        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.                         Soelvsbergite.
+  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.
+  Ornoeite.                           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 deg. of, at intervals of 10 deg..  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 deg. of, at latitudes 0 deg. to 90 deg..  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
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