GEOLOGICAL SURVEY CIRCULAR 92

November 1950

TOPOGRAPHIC INSTRUCTIONS 

BOOK1

Part 1-A 

PREFACE AND CONTENTS

Prepared by

Topographic Surveys Section

Research and Technical Control Branch

Topographic Division
UNITED STATES DEPARTMENT OF THE INTERIOR 

OSCAR E. CHAPMAN, SECRETARY

GEOLOGICAL SURVEY 

W. E. Wrather, Director

This circular has been prepared

as the first part of a manual of

Topographic Instructions

WASHINGTON, D. C.

Free on application to the Geological Survey, Washington 25, D. C.
GEOLOGICAL SURVEY 

TOPOGRAPHIC INSTRUCTIONS 

CONTENTS

Page 

Chapter 1A1. Purpose and use of topographic instructions ... 1

Manual format..................... 1

Manual objectives .... .............. 2

Chapter 1A2. Table of contents

Explanation ...................... 3

Book 1, General policies ................ 4

Book 2, Control surveys ................ 5

Book 3, Mapping procedures .............. 9

Book 4, Cartographic procedures ............ 12

Book 5, Map features and treatments, .......... 14

Book 6, Addenda.................... 16

GEOLOGICAL SURVEY

TOPOGRAPHIC INSTRUCTIONS

Book 1, Part 1A

Chapter 1A1 

PURPOSE AND USE OF TOPOGRAPHIC INSTRUCTIONS

November 1950

Chapter 1A1 

PURPOSE AND USE OF TOPOGRAPHIC INSTRUCTIONS

The primary purpose of Topographic Instructions is to guide members of the Topographic 

division in the preparation of topographic maps 

to prescribed standards. For the new employee, these instructions will also serve as a 

comprehensive textbook during his training 

period. The preceding Topographic Instructions were issued as Geological Survey Bulletin 788, in 1928. Since that date it has been 

necessary to issue numerous supplements in 

the form of technical memorandums or, in 

some cases, complete instruction pamphlets 

where radical changes in procedure had been 

developed. These older instructions ultimately will be entirely superseded by the current manual.

The need for a new manual has become 

acute because, with the increasing use of photogrammetry and other interdependent technical 

procedures, the coordinated operation of topographic mapping has become exceedingly complex. Furthermore, with operations carried 

on in four separate field regions, written instructions are essential to insure that map materials are interchangeable between regions 

and that each map series shall be uniform 

throughout the United States.

Responsibility for the preparation and revision of the manual officially rests with the 

Research and Technical Control branch of the 

Topographic division. However, the technical 

staff will require considerable assistance from 

experts and specialists in the regional organizations, particularly in preparing original 

drafts of chapters dealing entirely with operational procedures.

The procedures described herein are designed to produce maps that will meet standard 

specifications at the lowest cost. Changing 

conditions may require that specifications be 

changed from time to time, which in turn may

xThe number 1 A 1 signifies Book 1, Part A, 

Chapter 1 of the Geological Survey loose-leaf 

manual of Topographic Instructions. For a table 

of contents, see Chapter 1 A 2.

require that the procedures and instructions be 

revised accordingly; It is emphasized that the 

mapping procedures approved for use by these 

instructions should be scrutinized constantly 

for opportunities to reduce costs, lo reduce 

time required for an operation, or to improve 

quality. Suggestions to these ends are always 

in order.

MANUAL FORMAT ;

The contents of Topographic Instructions 

have been subdivided and grouped into books, 

parts, and chapters. For example, Book 2 

deals with control surveys, Part 2 A discusses 

triangulation field work, third-order, and 

Chapter 2A2 contains instructions for triangulation reconnaissance and signal building. The 

general arrangement of the contents is in chronological sequence in the order that work is performed, insofar as this is practical.

Each chapter provides essentially complete 

coverage of its subject. Whenever major revisions are required, the entire chapter will be 

reissued with an appropriate revision label. 

Likewise, a revised table of contents will be 

issued as often as warranted. It is planned that 

each chapter will be published as a separate and 

issued to employees of the Topographic division. 

These separates will be punched for the standard three-ring loose-leaf binder to facilitate 

the handling of revisions. When all of the chapters comprising a part have been published, 

they will be assembled under one cover and issued to the public as a Geological Survey circular.

Because the chapter is the unit of publication 

and also of revision, pages are numbered by 

chapters, each chapter starting with page one. 

Illustrations and tables are numbered consecutively within each chapter. An abstract of the 

subject matter is given at the beginning of each 

chapter and, when appropriate, a bibliography 

of reference material appears at the end of the 

chapter. Center headings and side captions 

serve to identify sections and articles within 

each chapter, to aid in classifying subject
4 (Ch. 1A1) TOPOGRAPHIC INSTRUCTIONS

matter and to facilitate reference. Although 

major changes in subject matter will be handled by revising and reissuing the chapter concerned, minor changes or corrections of errors may be issued as errata notices, coded 

or dated for identification.

Some of the chapters deal with subjects 

whose procedures already have been well established in the Topographic Instructions of 

1928 and subsequent technical memorandums. 

Other chapters contain entirely new material, 

concerning procedures heretofore not standardized. These latter chapters will be published only after they are reviewed and commented upon by operational groups in the regional offices. Also, some of these chapters 

probably will be issued provisionally until operational trials have confirmed the soundness 

of the procedures set forth therein.

MANUAL OBJECTIVES

Each chapter is intended to be written for a 

reader having an engineering education or equivalent, plus six months of experience in topographic mapping work, three months of which 

were in the specific operation discussed in the 

text. Therefore, although each chapter is intended to be reasonably complete, general discussions and reference material are omitted.

One of the aims of the manual is to distinguish for the employee between required procedures and permissible alternatives, as well 

as between specific and general procedures. 

Whenever a single procedure is specified, the 

use of an alternative procedure will usually not

be sanctioned, until formally recommended by a 

Region or Staff Engineer, and approved by the 

Chief Topographic Engineer. When two or more 

alternative procedures are suggested, any of 

the suggested procedures, or other newly devised procedures, may fee authorized by e*ach 

Region Engineer, always provided that the procedure selected will produce equally satisfactory results, at comparable costs. Similarly, 

when only general procedures are specified, 

each Region Engineer will be expected to determine the specific procedures to be used in 

his Region.

All members of the Topographic division 

have a vital interest both in the welfare of the 

organization and in increasing the rate of progress toward completion of the mapping of our 

country. The surest way to promote these objectives is to strive continually to keep the 

division in the forefront in developing new or 

improving older methods or equipment, in improving products, and in maintaining economical operation. Because these improvements 

and developments should be reflected quickly in 

the official operating instructions, all members 

of the organization are again urged to participate in constructively criticizing these instructions, and to make suggestions for their improvement.

/ 

Gerald 

&

FittfGerald

Chief Tojfographic Engineer
GEOLOGICAL SURVEY

TOPOGRAPHIC INSTRUCTIONS

Book 1, Part 1A

Chapter 1A2 

TABLE OF CONTENTS

Explanation

Book 1 - General policies

Book 2 - Control surveys

Book 3 - Mapping procedures

Book 4 - Cartographic procedures

Book 5 - Map features and treatments

Book 6 - Addenda

November 1950

TABLE OF CONTENTS

Chapter 1A2 1

TABLE OF CONTENTS 

EXPLANATION

A chapter has been assigned for each topic now deemed appropriate 

for inclusion in this manual. As the detailed instructions are developed, 

it may be found desirable to revise some of these titles, to add new 

chapters, or to omit some of those now proposed. Therefore, space 

has been provided for writing in a reasonable number of changes in the 

Contents, pending publication of a revised.issue.

Also, spaces have been provided after each chapter title for notations regarding date of original issue and date of any revision that may 

be published. These dates will be included in future issues of a revised table of contents. If these spaces are filled as chapters are 

issued they will provide a convenient means of indicating the publication status of each chapter, that is, whether it has been issued, and 

whether it has been revised.

1The number 1 A 2 signifies Book 1, Part A, Chapter 2 of the Geological Survey loose-leaf manual of Topographic Instructions.
4 (Ch. 1A2) TOPOGRAPHIC INSTRUCTIONS

Book 1. GENERAL POLICIES

Part 1 A. Preface and contents

Date Date 

Issued Revised

Chapter 1A1. Purpose and use of topographic

instructions ......... .11 - 50

1A2. Table of contents ....... - 11-50

Part IB. General specifications for standard 

topographic maps

Chapter 1B1. Map publication scales 

1B 2. Contour intervals . .

1B 3. Accuracy specifications for 

topographic mapping . . .

IB4. Features shown on topographic 

maps ...........

1B 5. Map revision policies

1B 6. Quadrangle names and geographic 

index system ........

1B 7. Map projection and state grid 

systems. ........

Part 1C. General procedures

Chapter 1 C 1. Outline of general procedures for 

mapping. ..........
TABLE OF CONTENTS (Ch. 1A2) 5

Book 2. CONTROL SURVEYS

Part 2 A. Triangulation field work, third-order 

Chapter 2 A1. Triangulation for map control. . ..

2A2. Triangulation reconnaissance and 

signal building.......

Date Date 

Issued Revised

2 A3. Equipment for triangulation. . . ..

2 A4. Observing horizontal angles in 

triangulation. ........

2 A5. Recording horizontal angles in 

triangulation. .......

2 A6. Observations and records of

vertical angles in triangulation ..

2 A7. Preparing triangulation data for

computation ...........

Part 2 B. Triangulation computations

Chapter 2 B1. Preliminary steps in triangulation 

computation ..........

2B2. Computing geodetic distances from 

triangulation. ..........

2 B 3. Computing geodetic coordinates

from triangulation ........

2 B4. Triangulation adjustment by least 

squares...........

2 B 5. Computing vertical-angle

elevations in triangulation. ....

2B6. Tabulating results of triangulation.
6 (Ch. 1A2) TOPOGRAPHIC INSTRUCTIONS

Date Date 

Issued Revised

Part 2C. Transit traverse, field work

Chapter 2C 1. General specifications for transit 

traverse ..........

2C2. Organization and equipment of

transit traverse party .....

2C 3. Positions to be located by transit

traverse ............

2C4. Taping for transit traverse . ....

2C 5. Instrument work in transit'

traverse ...........

2C 6. Field records for transit traverse

2 C 7. Azimuth observations for transit 

traverse ...........

2C8. Miscellaneous field operations in 

transit traverse .......

2C9. Traverse distances from subtense 

base triangulation ........

Part 2D. Transit traverse, computations

Chapter 2D1. General instructions to traverse 

computers. .........

2D2. Preparing traverse notes for 

computation .......

2D3. Computing latitude and departure ._

2D4. Computing geodetic and rectangular 

coordinates for traverse 

locations ..........._

2 D 5. Computing diagonal distances

between traverse locations ....

2D6. Tabulating results of transit

traverse ..........

2D 7. Calibration of tapes for transit 

traverse .........
TABLE OF CONTENTS (Ch. 1A2) 7

Date Date 

Issued Revised

Part 2D. Computations, transit traverse, 

Continued

Chapter 2D8. Computing transit traverse by

the plane segment method.....

2D 9. Computing plane coordinates from 

geodetic latitudes and departures.

2D10. Computing plane coordinates from 

grid azimuths ..........

2 D11. Computing geodetic coordinates 

from plane coordinates for' 

traverse locations .....

Part 2 E. Geodetic leveling, third-order

Chapter 2 E 1. Specifications and conditions 

governing leveling ....

2 E 2. Equipment for leveling. 

2 E 3. Spirit level bench marks

2E4. Organizing and operating a level 

party ............

2E 5. Summary of results and closures 

of level circuits . ......

2 E 6. Computing and adjusting level 

circuits..........

2 E 7. Tabulating results of leveling. ...
8 (Ch. 1A2) TOPOGRAPHIC INSTRUCTIONS

Date Date 

Issued Revised

Part 2F. Supplemental control 

Chapter 2 F 1. Supplemental control requirements 

2F2. Supplemental control planning. . ..

2F 3. Designation and marking of points 

for supplemental control .....

2F4. Photo-identification of control . ..

2F5. Supplemental control by stadia . . H - 50

2F6. Supplemental control by vertical 

angles ...........

2F7. Supplemental control by altimeter

2 F 8. Supplemental control by elevation 

meter. ...........

2F 9. Supplemental control from aerial 

oblique photographs .....

2F 10. Supplemental control from

terrestrial photographs.....

Part 2G. Miscellaneous processes

Chapter 2G1. Transformation of coordinates, 

Lambert projection. ....

2G2. Transformation of coordinates, 

transverse Mercator projection

2 G 3. Transformation of coordinates, 

universal Mercator projection.

2G4. Transformation of coordinates, 

interpolation method

2 G 5. Grid coordinates from shoran 

distances .........

2G6. Readjustment of triangulation 

datum. .........

2G7. Solution of equations in least 

squares.........

2 G 8. Survey adjustment by electrical 

analogue .........
TABLE OF CONTENTS (Ch. 1A2) 9

BookS. MAPPING PROCEDURES

Part 3 A. General procedures for mapping 

Chapter 3 A1. Project plans and specifications ..

3 A 2. Assembly of control data and

source material .........

Date Date 

Issued Revised

3 A3. Construction of map projections ..

3 A4. Symbols for photogrammetric

sheets .............

3 A5. Symbols for field sheets

Part 3 B. Mapping photography

Chapter 3B1. Geometry of the photograph ....

3B2. Photogrammetric cameras .....

3B3. Qualities of acceptable photography.

3B4. Planning vertical photography. . ._

3 B 5. Planning oblique and terrestrial 

photography .........

3B6. Planning twinplex photography . .. 

3 B 7. Planning trimetrogon photography..

3 B 8. Methods of procuring aerial

photographs ...........
10 (Ch. 1A2) TOPOGRAPHIC INSTRUCTIONS

Part 3 C. Photogrammetric mapping

Chapter 3 C 1. Outline of photogrammetric 

methods ........

3C 4. Planning and coordination of

photogrammetric operations . .

3 C 5. Base sheet preparation for

photogrammetric operations . .

3C6. Diapositive preparation. ....

3C7. Multiplex procedure .......

3C8. Kelsh Plotter procedure ....

3C9. Stereoplanigraph procedure . . . 

3CIO. Wild A6 procedure . ......

3 C 11. Wild A5 procedure . ......

3C12. Mahan Plotter procedure . . . .

3C13. Twinplex procedure .......

3C 14. Radial control for trimetrogon 

mapping ..........

3 C 15. Photo-interpretation for 

trimetrogon mapping

3C16. Photoalidade procedure. 

3C 17. Slotted templet procedure.

3 018. Utilizing shoran-controiled 

photography ......

Date Date 

Issued Revised

3C2. Sources of errors in

photogrammetric systems ....

3C 3. Training manual for beginners

in photogrammetry .......

3019. Photogrammetric rectification . .

3020. Mosaic preparation and use. . . .

3021. Map revision from photographs . .
TABLE OF CONTENTS (Ch. 1A 2) 111

Date Date 

Issued Revised

Part 3D. Field mapping

Chapter 3 D1. Fundamentals of plane-table 

operation ........

3 D 2. Specific operations in plane-table 

surveying ..........

3 D 3. Plane-table mapping without bases _

3D4. Plane-table mapping on planimetric 

bases ............_

3D5. Plane-table mapping on ph6tographic bases .......

3D6. Sheet-edge corrections in the field..

3D7. Field revision ........

3D8. Small-scale surveys . .....

3D9. Special project surveys ....

Part 3E. Field completion surveys 

Chapter 3 E 1. Advance field completion....

3E2. Preparing sheets for field completion surveys.........

3 E 3. Field inspection and completion 

surveys..........

3E4. Accuracy-testing surveys . . .

Part 3F. Office completion and preparation 

of manuscripts

Chapter 3 F1. Correction and assembly of 

original manuscripts. . .

3 F 2. Sheet-edge joining
112 (Ch, 1A2) TOPOGRAPHIC INSTRUCTIONS

Book 4. CARTOGRAPHIC PROCEDURES

Part 4 A. Drafting for color separation 

Chapter 4A1. Preparation of blue-line guides .

4 A2. Preparation of manuscripts for 

color separation .......

4 A3. Materials for map drafting . . . 

4A4. Color-separation drafting . . .

4 A 5. Symbols for color-separation

drafting...........

4A6. Style sheets. .........

4 A7. Relief shading procedures . . .

Part 4B. Preparation for engraving 

Chapter 4B1. Preparing copy for engraving. . 

4B 2. Editing sheets to be engraved . .

Part 4 C. Map checking and editing 

Chapter 4 C 1. Scope and function of map editing

4C2. Checking of color-separation

drawings ...........

4C3. Map editing.

4 C 4. Map lettering

4 C 5. Marginal data,

4C6. Lettering check and review of 

drawings .........

Date Date 

Issued Revised

4C 7. Composites (purpose and preparation) ............

4C8. Review edit. . . . 

4 C 9. Editing for reprints

4 C10, Editing maps prepared by other 

agencies .........
TABLE OF CONTENTS (Ch. 1A2) 13

Date Date 

Issued Revised

Part 4D. Compilation of small-scale maps

Chapter 4D1. United States and state map series .

4D2. Alaska reconnaissance series. . ..

4D3. Transportation maps. .......

4 D 4. International map of the world. . .

4D5. Index maps ...........

4D6. Status maps. ..........
'14 (Ch. 1A2) TOPOGRAPHIC INSTRUCTIONS

Book 5. MAP FEATURES AND TREATMENTS

Date Date 

Issued Revised

Part 5 A. Cultural features

Chapter 5 A1. General list of cultural features. .. 

5 A 2. Roads and road classification....

5 A 3. Buildings and urban areas .....

5A4. Railroads ............

5 A 5. Names and name over sheets ....

5 A6. Bridges, recreation facilities, and 

miscellaneous landmark features.

5 A 7. Civil boundaries. .........

5 A 8. Mapping public land subdivisions ..

5A9. Airports and military installations.

Part 5B. Hydrographic features 

Chapter 5Bl. Natural drainage features. .....

5B2. Artificial or controlled drainage

features. ............

5 B 3. Coastal features.

Part 5C. Hypsographic features 

Chapter 5 C 1. Topographic expression . . . 

5C2. Contouring special features. . 

5C3. Supplementary contours . . .

5C4. Spot elevations and other published 

elevations. ...........

5C5. Miscellaneous relief features. . .. 

5C6. Relief shading. ...........
N TABLE OF CONTENTS (Ch. 1A2) 15

Date Date 

Issued Revised

Part 5D. Land surface features 

Chapter 5 D1. Woodland . . .

5D2. Sand, gravel, rock, and lava 

areas..........

5 D 3. Mining ar eas
16 (Ch. 1A2) TOPOGRAPHIC INSTRUCTIONS

Book 6. ADDENDA

Part 6 A. Reference information 

Chapter 6 A1. Symbols on published maps .... _ 

6 A 2. Approved abbreviations ..... _

6 A 3. Glossary of names for topographic

features. ..........._

6 A 4. The public land survey system . . _ 

6 A5. The Board on Geographic Names ._

Part 6 B. Contract specifications

Chapter 6 B1. Specifications for aerial photography 

contracts ...... ....._

Date Date 

Issued Revised

6B2. Specifications for topographic 

mapping contracts .....

6 B 3. Specifications for control surveys 

contracts ..........

Part 6 C. Tables

InUrier Bupiieatins Station, Washlngten, B. c.