CHAPTER II.

SURVEYING WITH THE AID OF ANGULAR

INSTRUMENTS.

PAGES

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 Formulæ for the Solution of Plane

Triangles-Right-angled Triangles-Oblique Triangles - General
Trigonometrical Formulæ— 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 of Closing Error when the Error is considered to

be due to the Chaining only-Amount of 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

PAGES

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
Bearing

60-126

CHAPTER III.

LEVELLING.

on

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”
and " Height of Instrument" Systems—Example of Longitudinal
Section-Example of Level Book-Cross Sections-Checking

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-

PAGES

proximate Rule-Heights by Aneroid Barometer-Aneroid Baro-

metric Tables - Accuracy of Barometric Observations-Determina-

tion of Heights by Boiling Point Thermometer-Boiling Point

Thermometer Tables--Instruments: Aneroid Barometer—Mountain

Barometers-Boiling Point Thermometer—Levelling by Angular

Measurements or Trigonometrical Levelling-Calculation when

Curvature is allowed for- Calculation when both Curvature and

Refraction are allowed for– Reciprocal Observations for Cancelling

Refraction-Reduction of the observed Angles from the Summits

of Signals-Measurement of Heights by Observation to the Sea
Horizon-Precise Spirit Levelling - Instruments : Level — Kern
Level – Levelling Staff – Daily Adjustments—Field Work: Errors
from Unstable Supports – Atmospheric Errors-Available Working
Hours-Observing Staff Readings-Length of Sights-Corrections

– Accuracy and Cost of Precise Spirit Levelling-Adjustment of

Errors in Closed Circuits of Precise Levels-American Practice in

Precise Spirit Levelling ---Value of one Division of the Bubble Tube

-Correction for Inclination of Bubble to Upper Surfaces of Rings-

Correction for Collimation Line ---Correction for Inequality in the

Size of the Rings-Final Correction-Instructions for Precise Spirit

Levelling under the Mississippi River Commission

127-201

CHAPTER IV.

ADJUSTMENT OF INSTRUMENTS.

Chain - Thcodolite--Temporary Adjustments-To Set up the Instru-

ment over a Station--To Level up the Instrument --Focussing the

Object Glass and Eyepiece-Permanent Adjustments-Adjustment

of the Supports of the Horizontal Axis of the Telescope - Adjust-

ment of the Collimation Line-Accurate Method of Adjusting the

Collimation Line of Transit Theodolite-Adjustment of the Level

on the Telescope-Index Error of Vertical Circle-Centring of the

Object Glass and Eyepiece-Adjustment of the Diaphragm Ring

so that the Cross Hairs are truly Vertical and Horizontal —To

Replace the Cross Hairs—To Replace a Spirit Level or Bubble

Glass — Adjustment of the Sextant — Adjustment of the Box

Sextant - Adjustment of the Compass-To make the Needle truly

Horizontal - To make the Sights Perpendicular to the Compass

Plate - To Straighten the Needle-Adjustment of the Pivot Pin-

Pocket Magnifier--Magnetic Attraction about the Person-Sight

Slits - Remagnetising the Needle- Adjustment of the Level – To

make the Collimation Line coincide with the Axis of the Telescope

- To make the Spirit Level parallel to the Collimation Line-To

make the Telescope and Spirit Level together Perpendicular to the

Vertical Axis, or to make the Instrument “ traverse "-Adjustment

of the Y Level

CHAPTER V.

RAILWAY (INCLUDING ROAD) SURVEYS AND SETTING OUT.

PAGES

Home and Foreign Work-Parliamentary Surveys-Ordnance Survey

Maps — Special Local Considerations – Ruling Gradient and
Minimum Radius of Curve--Laying down Line on 6 in. Ordnance
Map-Fixing Gradients-Reconnaissance and Sketching in Loca-
tion on Map-- Plotting Sketched Location--Levelling the Longi-
tudinal Section-Correcting the 6 in. Ordnance-Reserencing-
Preparation of Parliamentary Plans-- Preparation of Parliamentary
Sections—Parliamentary Estimate-Board of Trade Regulations
for Light Railways—Example of Parliamentary Plan and Section
of Railway taken from actual practice - Working Surveys-
Revising and Improving Parliamentary Location-Final Location
of Line in Difficult Country-Pegging out Line-Pegs-Tangent
Points-Chainages and Survey of Existing Detail - Longitudinal
Section - Cross Sections — Working Plan -Working Section –
Fixing Gradients on Working Section-Levels on Working Section

- Cuttings and Banks on Working Section-New Works and

Existing Details on Working Section-Examples of Working Plan

and Working Section of Railway taken from actual practice-

Kuling Gradients-Train Load-Speed-Locomotive Power and

Train Resistance-Maximum Gradient_“ Pusher” Gradients -

Minimum Radius of Curve-Compensating Gradients on Curves-

Cost of Line, Light Railway-Details of the Field Work of Working

Survey and Pegging out : Instruments—Steel Band and Tapes -

Ranging Rods, &c.—Chainmen - Pegging out Centre Line -Chain-

ages and Survey of Detail — Bridges--Setting out Curves --Calcula-

tion of Length of Tangents - Calculation of Deflection Angles-

Exact Formula for Calculation of Deflection Angles-Calculation

of Length of Curve-Chainage of Tangent Points and Deflection

Angle for each Peg on Curve-Check on Calculation of Deflection

Angles--Laying off the Deflection Angles and Putting in Pegs on

Curve-Check on Laying off the Deflection Angles - Check on

Chaining Round Curve --Final Error in Setting out Curve-Con-

tinuing Work after Setting out Curve –Chaining to be “through

--Shifting the Instrument forward to Intermediate Point on

Curve — Curve to Lest - Transition Curves - Froude's Curve of

Adjustment-Setting out Transition Curves—“Cant”—Transition

Curves between Reversed Curves Vertical Curves at Changes

of Gradient-Setting out of Work during Construction : Transser-

ring Tangent Points-Setting out Fence Widths-Levelling in

Tops and Bottoms of Slopes-Setting out Bridge and Culvert

Foundations-Setting out Culverts—Setting out Bridge Abutments

-Other Setting out : Centre Lines and Levels in Cuttings and

Banks—“Boning Rods”—“Crossheads "-Allowance for Shrink-

age and Settlement-Bench Marks and Checking through Levels --

To Locate a Given Level

PAGES

CHAPTER VI.

TACHEOMETRY OR STADIA SURVEYING.

Tacheometry-Principle of the Stadia -Distance and Height Measure-

ment by Simple Vertical Angles, Bell-Elliott Tangent Reading

Tacheometer - Barcenas' Tangential Method — Principle of the

Tacheometer— Distance apart of Stadia Hairs-- General Rules in

Stadia Work—Methods of Determining Distance apart of Stadia

Hairs and other Constants-Porro's Stadia Telescope—Troughton

& Simms' Tacheometer-Specially Graduated Staff-Stadia Tables

for Horizontal Sights-Inclined Sights: Staff held Vertical-

Inclined Sights: Staff held Perpendicular to Line of Sight-Errors

in Distance and Level with Staff held Perpendicular to Collimation

Line -- Error from badly held Staff — Tables for making the
Reductions Stadia Table for Inclined Sights -- Reducing the
Levels-For Back Sights-For Fore Sights-Field Book-Field
Work-Micrometer for Long Sights-Best Class of Instrument for
Tacheometry-Office Work — Special Protractor – Accuracy of
Tacheometry or Staclia Surveying-Tangential System -Subtense
System--Comp:ırison of the two Systems—Levelling—American
Practice in Tacheometry or Stadia Surveying – Example of
Tacheometer or Siadia Survey

255-284

CHAPTER VII.

TUNNEL ALIGNMENT AND SETTING OUT.

Sursace Alignment-Surface Alignment over Hills--Example of Surface

Alignment over Hills: Alignment of the Totley Tunnel - The
Alignment Aboveground—The Alignment Underground-Surface
Alignment in Towns-Instruments for Setting out Tunnels-Setting
out Curves in Tunnels—Taking Measurements-Observing Angles
-- Marking Centre Line on Surface-Traversing between Shafts-

Transferring Surface Line down Shafts—Setting out Underground

Line-Marks for fixing Underground Line — Transferring Surface

Line down Shasts when Plumb Bobs cannot be used-Underground

Sights and Lamps-Illuminating Cross Hairs of Telescope-Ar-

rangement for Sighting on Wires Suspended in Shast — White

Reflectors to Verniers-Alignment of the Mersey Tunnel-Align-

ment of Dunmail Rise Tunnel on Thirlmere Aqueduct – Examples

of Errors in Alignment of Long Tunnels-Levels-Transferring

Levels down Shafts — Underground Bench Marks — Checking

Underground Levels and Centre Line through between Shafts-

Setting Ribs and Profiles--Setting Segments of Iron-lined Tunnels