Page images

Undeveloped Country, and as these are conducted under very different conditions from home work, the information thus afforded should prove eminently useful to those who may be called upon to carry out surveys in new countries or undeveloped regions.

A chapter has also been devoted to Astronomical Observations Used in Surveying. These are generally necessary in surveys in new countries, and hitherto when such information has been required search has been necessary in various different works. Being here collected and treated in one chapter, the information will be readily available for reference.

Many examples of surveys, taken from actual practice, have been given throughout the volume.


July 1902.


Instruments: Chain-Reading the Chain-Laying out Chain on Ground
-Arrows-Ranging Rods and Flags-Laths-Whites-Steel Tapes

-Linen Tapes--Steel Band-Adjusting the Chain-Cross Staff

Optical Square-Line Ranger-Use of the Chain-Chaining on

Slopes-Accuracy of Ordinary Chaining-Obstacles to Measuring

-Setting out a Right Angle with the Chain-Chaining across a

River or other Obstacle-Surveying with the Chain only---Recon-

naissance-Sketching-Field Book-Testing the Chain-Chainmen

-Examples of Surveying with the Chain only-Tie Lines - Offsets-

Field Book-Sketch and Fixing Stations-Long Offsets-Best Form

of Triangles-General Principles to be observed in laying out the

Chain Lines-Surveying a Pond or Plantation with the Chain

only-Fully detailed Example of Chain Survey-Fixing Positions

of Buildings-Ranging Line across Elevations or Depressions-

Marking Stations with Pegs-Ranging Intermediate Points in Long

Lines--Cutting Down Hedges and Fences-Clearing-up Ground

after Survey--Plotting the Survey: Scales-Drawing Instruments

-Drawing Paper-Plotting Plotting Offsets-Colouring-Con-

ventional Signs for delineating various objects on Plans--North

Point-Margin-Printing-Survey executed with Incorrect Chain-

Measures of Length-Measures of Area--Computation of Areas-

Give and Take Lines-Area of Triangles: Ordinary Method-Cal-

culation of Area from Figures in Field Book-Area of Irregular

Strip of Ground-Simpson's Rule for Calculation of Areas-Instru-

ments for Measuring Areas: Amsler's Planimeter-The Hatchet

Planimeter-Stanley's Computing Scale-Area of Survey executed

with Incorrect Chain-Copying Plans-Enlarging and Reducing

Plans-The Pantagraph-The Eidograph-Lithographing Plans-

Reducing Plans by Photography -


Instruments: Theodolite- Everest Theodolite Plain Theodolite-
Vernier Circumferentor or Surveying Compass-Whitelaw's Theo-
dolite and Mining Dial-Sextant-Box Sextant-Use of Box
Sextant-Theory of the Sextant-Measuring Angles with Box
Sextant when Ground is not Level-Prismatic Compass-Pocket
Compass-Plane Table-Range Finders: The Labbez Telemeter-
The Weldon Range Finder-The Bate Range Finder--Care of
Instruments-Trigonometrical Formula for the Solution of Plane
Triangles-Right-angled Triangles-Oblique Triangles - General
Trigonometrical Formula-Measuring Angles with the Theodolite
-Method of Repetition-Using both Faces of the Instrument-
Accurate Method of setting Instrument in Line-Method of con-
ducting an Ordinary Small Survey with the Theodolite-Field
Book-Reconnaissance of Ground-Practical Hints-Obstacles to
Measuring-Crossing a River-Example of an Ordinary Small
Survey with the Theodolite-Traverse Surveying-Example of an
Unclosed Traverse Survey-Ordinary Method of taking Bearings
-Method of avoiding Errors of Adjustment of Instrument in
taking Bearings--Plotting by Distances and Bearings with Pro-
tractor-Latitudes and Departures-Example of Calculation of
Latitudes and Departures-Traverse Tables-Example of Use of
Traverse Tables-Plotting by Latitudes and Departures-Checks
on Unclosed Traverse-Example of Closed Traverse Survey——
Checks on Closed Traverse-Checks on Plotting of Closed Traverse
-Graphic Adjustment of Closing Error-Adjustment of Closing

Error by Calculation-Example of Adjustment of Closing Error

by Calculation-Adjustment of Closing Error when some of the

Measurements may be considered more accurate than others-

Adjustment Closing Error when the Error is considered to

be due to the Chaining only-Amount Closing Error allow-

able in practice-Compass Traverse Surveys-Variations of the

Compass: Annual Variation-Diurnal Variation-Dip of Magnetic

Needle-Local Attractions-Town Surveys: Example of Town

Survey-Surveying with the Box Sextant-Surveying with the

Prismatic Compass-Instruments for Approximate Measurement

of Distances-By a 2 ft. Rule-Perambulator-Pedometer and

Passometer-Trocheameter-Example of Prismatic Compass and

Passometer Survey - Surveying with the Pocket Compass ·

Surveying with the Plane Table Photographic Surveying

Advantages of the Photographic Method of Surveying — Field

Work-Office Work-Levels - - Contours by Photographic Sur-

veying-Cost of Photographic Surveying Plotting the Survey:

Protractors-Section Paper - Computation of Areas: Areas of


Triangles-Calculation of Area of Closed Polygon from Lengths
and Bearings-To Cut Off a Given Area by a Straight Line Start-
ing from a Given Point in the Boundary of a Survey-To Cut Off
a Given Area from a Survey by a Straight Line with a Given

[ocr errors]



and "

Instruments: Water Level-Spirit Level—Radius of Curvature of
Bubble Tube Sensibility-Accurate Measurement of Small Vertical
Angles by means of Bubble Tube of Spirit Level-Angular Value
of one Division of Bubble Tube-Measurement of Small Angles
with Bubble Tube-Circular Spirit Level-Dumpy Level—The Y
Level-Levelling Staff-Levelling with the Spirit Level: Detached
Levels-Continued Series of Levels-Field Book: "Rise and Fall"
System-Booking the Levels-Reducing the Levels-Check on
Reducing the Levels-Datum-Bench Marks-Reduced Levels-
Plotting the Levels: Longitudinal Section-Readings near Top
of Staff-Field Book: "Collimation" or "Height of Instrument"
Method-Intermediate Sights-Comparison of "Rise and Fall"
Height of Instrument" Systems-Example of Longitudinal
Section-Example of Level Book-Cross Sections-Checking
on to Bench Marks or "Checking Back" Hand Level-
Clinometer - Cross Sectioning with the Clinometer -- Cross
Sectioning with the Theodolite - Contours - Vertical Distance
between Contour Lines - Determination of Contour Lines-
Second Method-Interpolation of Contours-Graphic Method of
Interpolating in Contours-Ridge and Valley Lines-Sketching
and Inking in Contours-Calculation of Contents from Contour
Lines Delineation of Ground by Hatchings — Delineation of
Ground by Shades from Light Falling Vertically - French
Method-German Method or Lehmann's Method-Delineation of
Ground by Shades from Light Falling Obliquely-Correction of
Levels for Curvature - Refraction-Other Instruments: Plumb
Line Levels-Reflecting Levels-Boning Rods-Practical Hints,
Obstacles and Difficulties-Change Points-Steep Slopes-Levelling
Across a Hill-When the Staff is too low or too high-When the
Staff is too near to read the Divisions-Board Fence-Wall-House
-Sun-Personal Error-To Locate a Given Level-Reciprocal
Levelling-Hypsometry or Levelling with the Barometer-Correc
tion for Temperature of Mercury-Correction for the Temperature
of the Air-Correction for Latitude-Correction for Height of
Lower Station-Correction for Decrease of Gravity on a Vertical-
Mercurial Barometric Tables-Example of Use of Tables --French
Barometers-Babinet's Simplified Formula-Belville's Short Ap-

[ocr errors]



« PreviousContinue »