A Treatise on Levelling, Topography and Higher Surveying

Front Cover
D. Appleton, 1884
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Contents

AXT PA0K 19 Continuous Waterlevels
10
Visual Waterlevels
11
The Spiritlevel
12
Blocklevel
13
Level with Sights
14
The Telescope Level
15
The Y Level
16
The Crosshairs
17
Supports
18
First Adjustment
19
Second Adjustment
20
Centring the Objectglass and Eyepiece
21
Adjustment by the Peg Method
22
Verification by another Telescope v
23
Gravatts Level
24
Tripods
25
Target
26
Verniers
27
Speaking Rods
28
THE PRACTICE ART TAGE 52 Field Routine
30
Fieldnotes
32
First Form of Fieldbook
33
Second Form of Fieldbook
35
Third Form of Fieldbook
38
Best Length of Sight
39
Benchmarks
40
Limits of Precision
41
Crosslevels
42
DIFFICULTIES 67 Steep Slopes
43
When the Rod is too low
45
Levelling across Water
46
Through a House
47
Wind
48
Its Nature
49
Staking out Work
50
To Locate a Level Line
51
To run a Grade Line
52
Vertical Surveying
53
Vertical Angles
54
Instruments
55
Slopes
56
Adjustments
58
FieldWork
60
Angular Profiles
61
Burniers Level
62
CHAPTEE H SIMPLE ANGULAR LEVELLING A For Short Distances 98 Principle
63
B For Greater Distances 100 Correction for Curvature
64
Correction for Refraction
65
Correction for Refraction
66
Reciprocal Observation for cancelling Refraction
67
When the Height of the Signal cannot be Measured
68
Levelling by the Horizon of the Sea
69
COMPOUND ANGULAR LEVELLING 110 By Angular Coordinates in one Plane
70
By Angular Coordinates in several Planes
71
PRINCIPLES AND FORMULAS ART PAG 113 Principles
73
Correction for Temperature of the Mercury
74
Eules for calculating Heights
75
To Correct for Latitude
76
French Formulas
77
Babinets Formula
78
Mountain Barometers
79
The Aneroid Barometer
80
Accuracy of Barometric Observations
81
Forms of Ground
90
Sketching Ground hy Contours
91
Conventionalities
92
Their Direction
93
Degree of Shade
94
Shades by Contourlines
95
Diapason of Tints
97
CONVENTIONAL SIGNS 166 Signs for Natural Surface
98
Signs for Water
99
ART PAGE 169 Colored Topography
100
Signs for Miscellaneous Objects
101
Scales
103
UNDERGROUND OR MINING SURVEYING 172 Objects
105
The Old Method
106
The New Method
108
The Mining Transit
109
Second Object
110
When the Mine is entered by a Shaft Ill 181 To Dispense with the Magnetic Needle
111
Reducing Several Courses to One
112
Third Object
113
PART VI
115
Description of the Sextant
117
The Box Sextant
118
How to Observe
120
ABT PAGB 192 To Set Out Perpendiculars
121
To Measure a Line one end being inaccessible
122
Otherwise
124
Artificial Horizon
125
The Sun
126
To Measure Slopes
127
Oblique Angles
128
Advantages of the Sextant
129
PART VII
131
The Lowwater Line
132
In Narrow Water
133
Finding the Position of a Boat on a Seacoast
134
Trilinear Surveying
135
Instrumental Solution
137
Between Stations
138
The Soundingline
139
ART FAGS 220 Tides
140
Mean Level of the Sea
141
Tide Gauges
142
Tide Tables
143
Gauges in Bends
144
THE CHART 229 Methods of Fixing Points on the Chart
145
Conventional Signs
146
SPHERICAL SURVEYING OR GEODESY CHAPTER I THE FIELDWORK 231 Nature
147
Outline of Operations
148
Corrections of the Base
152
A Broken Base
153
Choice of Stations
154
Signals
157
Observations of the Angles
159
Reduction to the Centre 16
160
Spherical Excess
162
Correction of the Angles
164
Methods
165
Legendres Method
166
Problem 1
167
Second Solution i68 253 Problem II
168
Lees Formulas
170

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Page 144 - All buoys along the coast, or in bays, harbors, sounds, or channels, shall be colored and numbered, so that passing up the coast or sound, or entering the bay, harbor, or channel, red buoys with even numbers shall be passed on the starboard hand, black buoys with uneven numbers on the port hand, and buoys with red and black stripes on either hand. Buoys in channel-ways shall be colored with alternate white and black perpendicular stripes.
Page 171 - ... of rectangular axes referred to one of the points of the triangulation, the latitude and longitude of which are known, — y being the ordinate in the direction of the meridian, and x the ordinate perpendicular to it, — the...
Page 1 - ... a curved line, because it is parallel to the curvature of the sea. But for all ordinary purposes a level line and a horizontal line are synonymous even for leveling operations conducted over such great distances as to be affected by the curvature of the earth. A level surface may also be defined as one which is everywhere perpendicular to the direction of gravity as indicated by a plumb-line; and the spirit-level, like the plummet, is a device for utilizing the law of gravity to estab lish a...
Page 12 - ... that a longitudinal section is a segment of a circle. If the tube is not ground to an an even curvature the bubble will not travel the same distance for every minute of arc to the extreme ends of the tube, and an otherwise perfect instrument will not work well. Fig. C. A line tangent to the circular arc at its highest point, as indicated by the middle of the bubble, or a line parallel to this tangent, is called the axis of the bubble tube. This axis will bo horizontal when the bubble is in the...
Page 166 - ... of the true spherical excess, the sines of these angles will be proportional to the lengths of the opposite sides, and the triangle may therefore be calculated as if it were plane.
Page 14 - Otherwise, if the bubble.tube is capable of movement, raise half.way back to the middle by this means, and the other half by raising or lowering one end of the block, because the reversion has doubled the error. Repeat this, if necessary. Circular LeveL The upper surface of this is spherical. It will therefore indicate a level in every direction, instead of only one, as does the preceding. It is adjusted like the last one, but in two directions, at right angles to each other.
Page 43 - Steep Slopes. In descending or ascending a hill, the instrument and the rod should be so placed that the sight should strike as near as possible to the bottom of the rod on the up-hill side, and the top of the rod on the down-hill side. Try this by levelling over two screws, setting the instrument so that one pair of opposite plate-screws shall point in the direction of the line, but do not be too particular ; it is a waste of time.
Page 132 - For higher or lower temperatures add or subtract 1| foot for each degree of Fahrenheit. If a wind blows with or against the movement of the sound, its velocity must be added or subtracted. If it blows obliquely, the correction will evidently equal its velocity multiplied by the cosine of the angle which the direction of the wind makes with the direction of the sound.* If the gun be fired at each end...
Page 119 - The line of collimation of the telescope is an imaginary line, passing through the optical centre of the object-lens, and a point midway between the two parallel wires. These wires are made parallel to the plane of the sextant by revolving the tube in which they are placed. To see whether the line of collimation of the telescope is in adjustment, bring the images of two objects, such as the sun and moon, into contact at the wire nearest the instrument, and then, by moving the instrument, bring them...
Page 73 - ... water are determined by the difference of the depths below the top of the water. The desired height of the atmosphere above any point, such as the top of a mountain, or the bottom of a valley, is determined by weighing it. This is done by trying how high a column of mercury or other liquid the column of air above it will balance ; or what pressure it will exert against an elastic box containing a vacuum, etc., etc.

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