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SURVEYING AND LEVELLING

By S. C. RANGWALA & P.S. Rangwala

Edition ISBN Size Binding Pages : 6th Revised and Enlarged Edition : 2011 : 978 - 93 - 80358 - 27 - 7 : 135 mm × 210 mm : Paperback with 4 color Jacket Cover : 584 + 24

Charotar

` 225.00 CoNteNt

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 : : : : : : : : : : : : : : : : : : : : : : : : INTRODUCTION SCALES LINEAR MEASUREMENTS OF DISTANCES CHAIN SURVEyING AND RANGING CROSS STAFF CHAIN SURVEyING AND INSTRUMENTS COMPASS SURVEy LEVELLING CONTOURING PLANE TABLE SURVEy COMPUTATION OF AREAS COMPUTATION OF VOLUMES MINOR INSTRUMENTS THEODOLITE PERMANENT ADjUSTMENTS OF LEVELS TACHEOMETRIC SURVEyING CIRCULAR CURVES TRANSITION CURVES VERTICAL CURVES FIELD ASTRONOMy THEORy OF ERRORS SETTING OUT WORKS HyDROGRAPHIC SURVEyING PHOTOGRAPHIC SURVEyING MODERN TECHNIQUES OF SURVEyING APPENDIx I MULTIPLE CHOICE QUESTIONS APPENDIx II ABBREVIATED TERMS

This text-book provides an up-to-date knowledge of the basic principles of Surveying and Levelling. The subject matter is canvassed alongwith therory, variety of examples, various types of survey techniques; survey instruments used in the field; measurement of distances, both vertical and horizontal; the direction of lines or agnles between the lines, where as various levelling instruments, principles, techniques, methods applied in levelling are given in this text book. The subject matter is expressed in a simple language and practical manner. The treatment is clear, methodical as well as interesting and easy to follow. The entire subject matter is systematically arranged in the chapters like: Introduction, Scales, Linear Measurements of Distances , Chain Surveying and Ranging, Cross Staff Chain Surveying and Instruments, Compass Survey, Levelling, Contouring, Plane Table Survey, Computation of Areas, Computation of Volumes, Minor Instruments, Theodolite, Permanent Adjustments of Levels, Tacheometric Surveying, Circular Curves, Transition Curves, Vertical Curves, Field Astronomy, Theory of Errors, Setting Out Works, Hydrographic Surveying, Photographic Surveying, Modern Techniques of Surveying. Appendix I contains Multiple Choice Questions and Appendix II showing abbreviated terms used in this book are added at the end of the book. All the articles have been given the numbers to enhance the readability and convenience of the reader. The book now contains * 367 * 218 * 22 * 480 self-explanatory and neatly drawn sketches solved problems useful tables questions at the end of the chapters.

About the book

The book should prove to be extremely useful to the Engineering students preparing for the Degree Examinations of all the Indian Universities, Diploma Examinations conducted by various Boards of Technical Education, Certificate Courses as well as for the A.M.I.E., U.P.S.C., G.A.T.E., I.E.S. and other similar competitive and professional examinations. It is also useful for the preparation of NATA (National Aptitude Test for Architecture), CEPT (Centre for Environmental Planning and Technology), SBST (School of Building Science and Technology), SID (School of Interior Design), AIEEE (Architecture), etc. It should also prove of interest to the practising professionals.

Checklist

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Chapter 1 : INTRODUCTION 1-1 General 1-2 Object of survey (1) Details (2) Scale 1-3 Purposes of survey 1-4 Classification of surveys 1-4-1 Engineering surveys (1) Reconnaissance survey (3) Location survey (2) Preliminary survey 1-4-2 Geodetic surveys 1-4-3 Plane surveys (1) Depending upon the shape of framework (2) Depending upon the type of instrument employed 1-4-4 Miscellaneous surveys (1) Archaeological surveys (6) Marine surveys (2) Astronomical surveys (7) Military surveys (3) Cadastral surveys (8) Mining surveys (4) City surveys (9) Topographical surveys (5) Geological surveys 1-5 Principles of surveying (1) Principle no 1 (2) Principle no 2 1-6 Uses of survey 1-7 Measurements and their units (1) Linear measurement (2) Angular measurements 1-8 Roll of Surveyor (1) Field operations (3) Use of instruments (2) Office work 1-9 Precision and accuracyin surveying QUESTIONS 1 Chapter 2 : SCalES 2-1 General (1) Engineer's scale (3) Representative fraction (2) Graphical scale 2-2 Requirements of a scale 2-3 Classification of scales 2-3-1 Plain scale 2-3-2 Diagonal scale 2-3-3 Vernier scale (1) Direct vernier (4) Double vernier (2) Retrograde vernier (5) Double-folded vernier (3) Extended vernier 2-3-4 Miscellaneous scales (1) Comparative scales (3) Shrunk scale (2) Scale of chords 2-4 Plans and maps 2-5 Scale for survey maps and plans 2-6 Correction due to use of wrong scale QUESTIONS 2 Chapter 3 : lINEaR MEaSUREMENTS Of DISTaNCES 3-1 General (1) Direct methods (2) Indirect methods 3-2 Direct methods of linear measurements 3-2-1 Direct methods without instruments (1) judging the distance (2) Pacing (3) Time interval 3-2-2 Direct methods with instruments (1) Chain (4) Pedometer (2) Odometer (5) Perambulator (3) Passometer (6) Speedometer 3-3 Types of chains (1) Metric chain (4) Gunter's chain (2) Steel band (5) Revenue chain (3) Engineer's chain 3-4 Testing and adjusting of chain

Instruments for marking stations (1) Arrows (7) Plumb bob (2) Hammer (8) Ranging poles (3) Laths (9) Ranging rods (4) Nails or spokes (10) Whites (5) Offset rod (11) Twig splits (6) Pegs 3-6 Types of tapes (1) Cloth or linen tape (3) Metallic tape (2) Invar tape (4) Steel tape 3-7 Tape corrections (1) Correction for absolute length or standardization (2) Correction for height above mean sea level (3) Correction for pull or tension (4) Correction for sag (5) Correction for slope or vertical alignment (6) Correction for temperature QUESTIONS Chapter 4 : ChaIN SURvEyINg aND RaNgINg 4-1 General 4-2 Principle of chain survey 4-3 Survey stations 4-4 Survey lines (1) Base line (3) Tie line (2) Check line 4-5 Offsets (1) Definition (3) Taking perpendicular offsets (2) Types (4) Number of offsets (5) Degree of accuracy in taking offset (6) Limiting length of offset 4-6 Ranging (1) Definition (2) Purposes 4-7 Types of ranging 4-7-1 Direct ranging (1) Ranging by eye (2) Ranging by line ranger (3) Ranging by theodolite 4-7-2 Indirect ranging (1) Random line ranging (2) Reciprocal ranging 4-8 Chaining on plain ground 4-9 Points to be observed during chaining (1) Folding and unfolding of (3) Reading the chain chain (4) Testing and adjusting chain (2) Number of arrows 4-10 Chaining on sloping ground 4-10-1 Direct method of chaining (1) Direction of work (4) Length of step (2) Error due to sag (5) Record of steps (3) Horizontality of chain 4-10-2 Indirect method of chaining (1) Hypotenusal allowance (3) Measuring difference in level (2) Measuring angle of inclination 4-11 Errors in ordinary chaining 4-11-1 Compensating errors (1) Adding or omitting full (5) Incorrect holding length of chain (6) Reading from wrong end (2) Calling numbers wrongly of chain (3) Displacement of arrows (7) Reading wrong numbers (4) Imperfect alignment (8) Wrong booking 4-11-2 Cumulative errors (1) Chain not being horizontal (4) Error due to sag (2) Chain not being straight (5) Incorrect ranging (3) Chain of incorrect length (6) Variation in temperature 4-12 Degree of accuracy in chaining work 4-13 Field book 4-14 Instruments required in chain survey 4-15 Procedure for carrying out chain survey 4-16 Plotting work with conventional signs QUESTIONS 4

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Chapter 5 5-1 5-2 5-3 5-4 5-4-1 5-4-2

General Purpose Basic principle Instruments for setting out perpendiculars Chain or tape Cross-staff (1) Adjustable cross-staff (3) Open cross-staff (2) French cross-staff 5-4-3 Optical square (1) Mirror type optical square (3) Site square (2) Prism type optical square 5-5 Cross-staff survey 5-6 Obstacles in chaining 5-6-1 Chaining free but vision obstructed 5-6-2 Chaining obstructed but vision free 5-6-3 Chaining and vision both obstructed QUESTIONS 5 Chapter 6 : COMPaSS SURvEy 6-1 General 6-2 Traversing and triangulation (1) Area covered by survey (2) Checks (3) Measurements (4) Nature of area (5) Period of work (6) Reconnaissance survey 6-3 Methods of measuring direction (1) Chain angles (2) Included angles 6-4 Magnetic needle (1) Broad needle (2) Edge bar needle 6-5 Pivot 6-6 Compass (1) Prismatic compass (4) Trough compass (2) Surveyor's compass (5) Tubular compass (3) Compass over a level 6-7 Tripods (1) Solid leg type (3) Telescopic leg type (2) Split leg type 6-8 Bearings (1) Definition (2) Meridians 6-9 Magnetic declination 6-10 Classification of declination (1) Diurnal variation (3) Secular variation (2) Annual variation (4) Irregular variation 6-11 Methods of designation (1) Quadrantal bearing system (2) Whole circle bearing system 6-12 Fore bearing and back bearing 6-13 Included angles from bearings 6-14 Local attraction (1) First method (2) Second method 6-15 Chain and compass survey 6-16 Plotting of compass survey (1) Included angles (2) Parallel meridian 6-17 Closing error 6-18 Errors in compass survey (1) Errors due to external forces (3) Personal errors (2) Instrumental errors 6-19 Precautions in using the compass 6-20 Accuracy and precision (1) Accuracy (2) Precision 6-21 Limits of precision QUESTIONS 6

: CROSS STaff ChaIN SURvEyINg aND INSTRMENTS

Chapter 7 : lEvEllINg 7-1 General 7-2 Definitions of some common terms in levelling (1) Backsight, foresight and (8) Level line intermediate sight (9) Level surface (2) Bench mark (10) Line of collimation (3) Change point or (11) Mean sea level turning point (12) Reduced level (4) Datum (13) Station (5) Elevation (14) Vertical angle (6) Height of instrument (15) Vertical line or plumb line (7) Horizontal line 7-3 Methods of levelling 7-3-1 Direct levelling (1) Simple levelling (5) Cross-sectioning (2) Differential levelling (6) Precise levelling (3) Reciprocal levelling (7) Check levelling (4) Profile levelling (8) Fly levelling 7-3-2 Indirect levelling (1) Barometric levelling (3) Trigonometrical levelling (2) Hypsometry 7-4 Principles of levelling (1) Change point (3) Position of level (2) Lengths of BS and FS (4) Starting and ending 7-5 Instruments for levelling 7-6 Types of levels (1) Dumpy level (4) Cushing's level (2) Cooke's reversible level (5) Tilting level (3) Wye or y-level (6) Gradientor or gradiometer 7-7 Levelling staff (1) Self-reading staff (1) Holding the staff (2) Target staff (2) Reading the staff 7-8 Essential parts of a level (1) Bubble tube (3) Telescope and its working: (2) Levelling head 7-9 Parallax and focussing 7-10 Defects of a single lens (1) Spherical aberration (3) Coma (2) Chromatic aberration 7-11 Parts of a telescope (1) Objective (3) Diaphragm (2) Eye-piece (4) Body with focussing arrangement 7-12 Optical characteristics of telescope 7-13 Accessories to a level (1) Bubble reflector (4) Dust cap (2) Clamp and slow motion (5) Quick setting levelling head screws (6) Ray shade and ray shade (3) Compass clinometer 7-14 Bench marks (1) Arbitrary bench marks (3) Permanent bench marks (2) GTS bench marks (4) Temporary bench marks 7-15 Temporary adjustments of levels 7-16 Entering the staff readings 7-17 Reduction of levels (1) Collimation system (2) Simplicity (2) Rise and fall system (3) Use (1) Accuracy 7-18 Difficulties in levelling 7-19 Curvature and refraction (1) Curvature (5) Distance to the visible (2) Refraction horizon (3) Combined correction (6) Dip of the horizon (4) Methods of correction (7) Remedies 7-20 Errors in levelling (1) Instrumental errors (3) Personal errors (2) Natural errors 7-21 Precision of levelling QUESTIONS 7

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Chapter 8 : CONTOURINg 8-1 General 8-2 Contour lines 8-3 Contour interval (1) Importance of the work (3) Nature of the ground (2) Money and time available (4) Scale of the map 8-4 Horizontal equivalent 8-5 Characteristics of contours (1) Closed loops (4) Indication of slope (2) Contour of same level (5) Ridge and valley (3) Hills and hollows (6) Saddle or pass 8-6 Location of contours (1) Direct method (2) Indirect method 8-7 Interpolation of contours (1) Estimation (3) Graphical (2) Arithmetical calculations 8-8 Contour drawing 8-9 Contour gradient 8-10 Uses of contours (1) Calculation of reservoir (6) Measurement of drainag capacity area (2) Contour gradients (7) Selection of route (3) Drawing of sections (8) Strategic points (4) Earthwork calculations (5) Intervisibility between two stations QUESTIONS 8 Chapter 9 : PlaNE TaBlE SURvEy 9-1 General 9-2 Instruments required for plane table survey (1) Alidade (2) Drawing board 9-3 Accessories required for plane table survey (1) Plumbing fork (3) Trough compass (2) Spirit level (4) Miscellaneous 9-4 Temporary adjustments of plane table (1) Centering (3) Orientation (2) Levelling 9-5 Methods of plane table survey (1) Radiation (3) Traversing (2) Intersection (4) Resection 9-6 Two-point and three-point problems 9-6-1 Two-point problem 9-6-2 Three-point problem (1) Mechanical method (3) Trial and error method (2) Graphical method 9-7 Errors in plane table survey 9-8 Advantages of plane table survey 9-9 Disadvantages of plane table survey QUESTIONS 9 Chapter 10 : COMPUTaTION Of aREaS 10-1 General 10-2 Methods for the computation of areas (1) Analytical method (3) Mechanical method (2) Graphic method 10-3 Geometrical figures 10-4 Measuring grids 10-5 Ordinates (1) Offsets at equal intervals (2) Offsets at unequal intervals 10-6 Co-ordinates 10-7 Planimeter 10-8 Method of using a planimeter 10-9 Zero circle (1) Wheel between tracing point and hinge (2) Wheel placed beyond hinge QUESTIONS 10

Chapter 11 : COMPUTaTION Of vOlUMES 11-1 General (1) Accuracy of the field work (2) Accuracy of the plotting (3) Method of calculation 11-2 Methods for computation of volumes 11-2-1 Cross-sections (1) Level section (2) Two-Ievel section (3) Side hill two-level section (4) Three-level section (5) Multi-level section 11-2-2 Spot levels 11-2-3 Study of contour plan 11-3 Prismoidal correction 11-4 Curvature correction for volumes (1) Equivalent areas (2) Two-level section and (2) Pappu's theorem three-level section (1) Level section (3) Side hill two-level section QUESTIONS 11 Chapter 12 : MINOR INSTRUMENTS 12-1 General 12-2 Abney level 12-2-1 Essential parts of abney level (1) Bubble tube (3) Square tube (2) Graduated arc 12-2-2 Working of abney level 12-2-3 Testing of abney level 12-3 Box sextant 12-3-1 Essential parts of box sextant 12-3-2 Principle of box sextant 12-3-3 Working of box sextant (1) Angle greater than 110° (4) Setting out an angle (2) Brightness of object (5) Unequal distances (3) Measuring vertical angles 12-3-4 Optical requirements and adjustments of box sextant (1) Adjustment of horizon glass (2) Adjustment of the planes of two glasses 12-4 Ceylon ghat tracer 12-4-1 Essential parts of ghat tracer (1) Hollow tube (3) Weight (2) Horizontal raked bar 12-4-2 Working of ghat tracer 12-5 De Lisle's clinometer 12-5-1 Essential parts of De Lisle's clinometer (1) Frame (3) Radial arm (2) Graduated arc 12-5-2 Working of De Lisle's clinometer 12-6 Eidograph 12-7 Foot-rule clinometer 12-7-1 Working of foot-rule clinometer 12-8 Hand level 12-8-1 Working of hand level 12-8-2 Adjustment of the hand level 12-9 Indian pattern clinometer 12-9-1 Essential parts of Indian pattern clinometer : (1) Base-plate (2) Eye-vane (3) Object-vane 12-9-2 Working of Indian pattern clinometer 12-9-3 Adjustment of Indian pattern clinometer 12-10 Pantagraph 12-11 Proportional compass 12-12 Watkin's mirror clinometer QUESTIONS 12

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Chapter 13 : ThEODOlITE 13-1 General 13-2 Essential parts of a transit theodolite (1) Telescope (7) Lower plate (2) Vertical circle (8) Upper plate (3) Index frame (9) Level tubes (4) Standards (10) Compass (5) Levelling head (11) Tripod (6) Two spindles (12) Plumb bob 13-3 Definitions and terms used for theodolite work (1) Axis of level tube (7) Horizontal axis (2) Axis of telescope (8) Line of sight (3) Centering (9) Swinging the telescope (4) Changing face (10) Transiting (5) Face left (11) Vertical axis (6) Face right 13-4 Micrometer theodolites 13-5 Temporary adjustments of theodolite (1) Setting up (3) Elimination of parallax (2) Levelling up 13-6 Measurement of horizontal angles 302 (1) Repetition method (2) Reiteration method 13-7 Measurement of vertical angles 13-8 Miscellaneous operations with theodolite (1) To lay off a horizontal angle (2) To lay off an angle by repetition (3) To locate the point of intersection of two straight lines (4) To measure deflection angles (5) To measure direct angles (6) To measure magnetic bearing of a line (7) To prolong a straight line (8) To run a straight line between two points 13-9 Theodolite traverse (1) By direct observation of angles (2) By fast needle method 13-10 Locating details in theodolite traverse (1) Locating by angle and distance from one transit station (2) Locating by angles from two transit stations (3) Locating by angle from one station and distance from another station (4) Locating by distances from two points on traverse line 13-11 Degree of accuracy in theodolite traversing 13-12 Plotting of theodolite traverse 13-13 Closing error 13-14 Angular error 13-15 Adjustment of bearings 13-16 Balancing the traverse (1) Bowditch's rule (2) Transit rule 13-17 Traverse table 13-18 Errors in theodolite work (1) Errors due to external forces (3) Personal errors (2) Instrumental errors 13-19 Fundamental lines and desired relations 13-20 Permanent adjustments of theodolite (1) To adjust the plate level (2) To adjust the line of collimation (3) To adjust the horizontal axis (4) To adjust the axis of the altitude bubble (5) To adjust the vertical circle (6) To adjust the striding level 13-21 Uses of theodolite 13-22 Typical problems on theodolite 13-23 Modern theodolites QUESTIONS 13

Chapter 14 : PERMaNENT aDJUSTMENTS Of lEvElS 14-1 General 14-2 Fundamental axes of the levelling instruments (1) Axis of the bubble tube and line of collimation (2) Axis of the bubble tube and vertical axis (3) Axis of the telescope and line of collimation 14-3 Principle of reversibility 14-4 Precautions to be taken during the permanent adjustments 14-5 Adjustments of dumpy level (1) Adjustment of the bubble tube (2) Adjustment of cross-hair ring (3) Adjustment of the line of collimation 14-6 Adjustments of y-level (1) To make the line of collimation coincide with the axis of the telescope (2) To make the axis of the bubble tube parallel to the line of collimation (3) To make the axis of the bubble tube perpendicular to the vertical axis: 14-7 Adjustments of Cooke's reversible level (1) To coincide the line of collimation with the axis of the telescope (2) To make the line of collimation perpendicular to the vertical axis (3) To make the axis of the bubble perpendicular to the vertical axis 14-8 Adjustments of Cushing's level 347 (1) To coincide the line of collimation with the axis of the telescope (2) To make the line of collimation perpendicular to the vertical axis (3) To make the axis of the bubble perpendicular to the vertical axis 14-9 Adjustments of tilting level (1) Adjustment of cross-hair ring (2) Adjustment of the line of collimation QUESTIONS 14 Chapter 15 : TaChEOMETRIC SURvEyINg 15-1 General 15-2 Instruments (1) Levelling or stadia rod (2) Tacheometer 15-3 Uses of tacheometry (1) Differential levelling (5) Topographic surveying (2) Photographic mapping (6) Traverses of low accuracy (3) Plane table (7) Trigonometric levelling (4) Profile levelling 15-4 Systems of tacheometric measurements 15-5 Stadia method (1) Principle of stadia method (8) Limiting length of sight (2) Determination of constants (9) Field work (3) Anallatic lens (10) Errors in stadia surveying (4) Inclined sights (11) Precision in stadia (5) Reduction of stadia notes surveying (6) Holding the staff (12) Typical problems of stadia (7) Reading the staff method 15-6 Subtense method (1) Principle of subtense method (2) Determination of constants (3) Advantages and disadvantages (4) Horizontal base subtense method (5) Subtense bar (6) Effect of angular error on horizontal distance (7) Typical problems of subtense method 15-7 Tangential method (1) Cases of observed vertical angles (2) Disadvantages (3) Typical problems of tangential method QUESTIONS 15

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Chapter 16 : CIRCUlaR CURvES 16-1 General (1) Horizontal curves (2) Vertical curves 16-2 Classification of circular curves 16-3 Simple curves (1) Definition (2) Designation (3) Notations 16-4 Elements of simple curve (1) External distance (2) Length of the curve (3) Length of the long chord (4) Mid-ordinate (5) Tangent distance 16-5 Location of tangents 16-6 Location of tangent points 16-7 Peg Interval 16-8 Normal chords and sub-chords 16-9 Setting out simple curves 16-9-1 Linear methods (1) Offsets or ordinates from the long chord (2) Successive bisection of arcs (3) Offsets from the tangents (4) Offsets from the chords produced 16-9-2 Angular methods (1) Rankine's method of tangential angle (2) Two theodolite method (3) Tacheometric method 16-10 Special problems in simple curves 16-11 Compound curves (1) Definition (2) Elements of compound curve 16-12 Setting out compound curves 16-13 Reverse or serpentine curves (1) Definition (2) Uses (4) Reverse curve between parallel straights (3) Elements of reverse curve QUESTIONS 16 Chapter 17 : TRaNSITION CURvES 17-1 General 17-2 Requirements of transition curve 17-3 Composite curve 17-4 Super-elevation 17-5 Centrifugal ratio (1) For roads (2) For railways 17-6 Length of transition curve (1) By arbitrary gradient (2) By time rate (3) By rate of change of radial acceleration 17-7 Ideal transition curve 17-8 Cartesian co-ordinates of the points 17-9 Calculation of deflection angles 17-10 Modifications of ideal transition curve (1) Cubic parabola (2) Cubic spiral 17-11 Characteristics of a transition curve (1) For cubic parabola (2) For cubic spiral 17-12 Lemniscate transition curve 17-13 Comparison of transition curves QUESTIONS 17

Chapter 18 : vERTICal CURvES 18-1 General 18-2 Grade or gradient (1) Percentage (%) (2) Ratio 18-3 Rate of change of gradient 18-4 Types of vertical curves (1) Summit or convex curves (2) Valley or sag or concave curves 18-5 Equation of vertical curve 18-6 Length of vertical curve (1) Permissible rate of change of grade (2) Sight distance 18-7 Sight distance of vertical curve at summit 18-8 Sight distance of vertical curve at sag (1) Sight distance is less than length of curve (S < L) (2) Sight distance is more than length of curve (S > L) 18-9 Vertical curve passing through a fixed point 18-10 Setting out vertical curves (1) Tangent correction method (2) Chord-gradient method 18-11 Typical problems on vertical curves (1) Tangent correction method (2) Chord-gradient method QUESTIONS 18 Chapter 19 : fIElD aSTRONOMy 19-1 General (1) Earth (2) Satellites (3) Stars (4) Sun 19-2 Some astronomical terms (1) Celestial sphere (14) Longitude (f) (2) Celestial horizon (15) Altitude (a) (3) Zenith (16) Co-altitude (4) Nadir (17) Azimuth (5) Terrestrial poles (18) Declination (d) (6) Terrestrial equator (19) Declination circle (7) Celestial poles (20) Co-declination (8) Celestial equator (21) Hour circle (9) Vertical circle (22) Hour angle (H) (10) Observer's meridian (23) Ecliptic (11) Prime vertical (24) Equinoctial points (12) Latitude (q) (25) Solastices (13) Co-latitude 19-3 Terrestrial latitude and longitude 19-4 Parallel of latitude 19-5 Nautical mile 19-6 Spherical trigonometry 19-7 Spherical triangle (1) Properties of a spherical triangle (2) Area of spherical triangle (3) Right-sangled spherical triangle 19-8 Some useful data 19-9 Astronomical triangle 19-10 Star at elongation 19-11 Star at prime vertical 19-12 Star at culmination or transit 19-13 Circumpolar stars 19-14 Star at horizon 19-15 Relationships between co-ordinates 19-16 Time (1) Sidereal time (2) Solar apparent time (3) Mean solar time (4) Standard time QUESTIONS 19

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Chapter 20 : ThEORy Of ERRORS 20-1 General (1) Climatic conditions (3) Instruments (2) Human limitations 20-2 Accuracy and precision (1) Accuracy (2) Precision 20-3 Types of errors (1) Mistakes (3) Accidental errors (2) Systematic errors 20-4 Some definitions (1) Conditional equation (8) Normal equation (2) Conditioned quantity (9) Observation equation (3) Direct observation (10) Observed value of (4) Independent quantity a quantity (5) Indirect observation (11) Residual error (6) Most probable error (12) True error (7) Most probable value of (13) True value of a quantity a quantity (14) Weight of an observation 20-5 Laws of accidental errors 20-6 Probability curve (1) Probable error of a single measurement (2) Probable error of the mean or average (3) Probable error of the sum 20-7 Most probable value 20-8 Average error and maximum error 20-9 Mean square error 20-10 Method of least squares (1) Direct observations of equal weight (2) Direct observations of unequal weight 20-11 Laws of weights 20-12 Rules for giving weights to the field observations 20-13 Distribution of error to the field observations QUESTIONS 20 Chapter 21 : SETTINg OUT WORKS 21-1 General 21-2 General considerations (1) Checking (4) Instruments (2) Direct scaling (5) Structural work (3) Important pegs 21-3 Control stations (1) Duration (3) Numbering (2) Location 21-4 Horizontal control 21-5 Vertical control 21-6 Setting out of structure (1) Co-ordinates from the site grid (2) Offsets from the base line (3) Offsets from the existing building 21-7 Setting out of important structures (1) Setting out bridges (4) Setting out dams (2) Setting out buildings (5) Setting out sewers (3) Setting out culverts (6) Setting out tunnels QUESTIONS 21

Chapter 22 : hyDROgRaPhIC SURvEyINg 22-1 General 22-2 Requirements of hydrographic survey (1) Bed profile (3) Shore details (2) Horizontal control (4) Vertical control 22-3 Shore line survey 22-4 Soundings (1) Sounding boat (4) Sounding machine (2) Sounding rods or poles (5) Fathometer (3) Lead lines 22-5 Location of soundings (1) By cross rope (2) By intersecting ranges (3) By one angle from the shore and one from the boat (4) By range and one angle from the boat (5) By range and one angle from the shore (6) By range and time intervals (7) By tacheometry (8) By two angles from the boat (9) By two angles from the shore 22-6 Reduction of soundings 22-7 Tides 22-8 Tide gauges (1) Non-registering tide gauges (2) Self-registering tide gauges QUESTIONS 22 Chapter 23 : PhOTOgRaPhIC SURvEyINg 23-1 General 23-2 Classification of photogrammetry (1) Aerial photogrammetry (2) Terrestrial photogrammetry 23-3 Application of photogrammetry 23-4 Mosaics (1) Nature of features (3) Scale (2) Projections QUESTIONS 23 Chapter 24 : MODERN TEChNIqUES Of SURvEyINg 24-1 General 24-2 Electronic distance measurement instruments (1) Geodimeter (3) Total station (2) Tellurometer (4) Distomat DI 1000 24-3 Global positioning system 24-4 Geographic information system (1) Raster method to store data in GIS (2) Vector method to store data in GIS 24-5 Remote sensing (1) Passive remote sensing (2) Active remote sensing QUESTIONS 24 Appendix I MULTIPLE CHOICE QUESTIONS Appendix II Abbreviated terms

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