Treatise on Levelling, Topography and Higher Surveying

Front Cover
D. Appleton, 1875 - Surveying - 173 pages
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Contents

WATERLEVELS ART PAGB 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
The Level IT 31 Supports
18
First Adjustment
19
Second Adjustment
20
Centring the Objectglass and Eyepiece
21
Adjustment by the Peg Method
22
Verification by another Telescope
23
Gravatts Level
24
Tripods
25
Target
26
Verniers
27
Speaking Rods
28
ART PAGS 62 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
Steep Slopes
43
When the Rod is too low
45
Levelling across Water
46
Through a House
47
Wind
48
LEVELLING LOCATION 81 Its Nature
49
To Locate a Level Line
51
To run a Grade Line
52
METHODS AND INSTRUMENTS ABT PAGE 87 Vertical Surveying
53
Vertical Angles
54
Instruments
55
Slopes
56
Adjustments
58
FieldWork
60
Angular Profiles
61
Burniers Level
62
CHAPTER 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
By Angular Coordinates in one Plane
70
By Angular Coordinates in several Planes
71
ABT PAGE 113 Principles
73
Correction for Temperature of the Mercury
74
Rules for calculating Heights
75
To Correct for Latitude
76
French Formulas
77
Babinets Formula
78
INSTRUMENTS 126 Mountain Barometers
79
The Aneroid Barometer
80
Accuracy of Barometric Observations
81
Forms of Ground
90
Sketching Ground by Contours
91
Conventionalities
92
Their Direction t
93
Degree of Shade
94
Shades by Contourlines
95
Diapason of Tints
97
Signs for Natural Surface
98
Signs for Water
99
ABT PASS 169 Colored Topography
100
Signs for Miscellaneous Objects
101
in Scales
103
PART V
105
The Old Method
106
The New Method
108
The Mining Transit
109
CHAPTER H LOCATING NEW LINES 178 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 1
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
ABT PAGE 220 Tides
140
Mean Level of the Sea
141
Tide Gauges
142
Tide Tables
143
Ganges in Bends
144
THE CHART 229 Methods of Fixing Points on the Chart
145
Conventional Signs
146
PART VIII
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
160
The Angles
162
Correction of the Angles
164
ART PAGE 247 Methods
165
Legendres Method
166
Problem 1
167
Second Solution T
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 89 - ... lines of greatest slope when looking along them from below upwards. They can be readily determined by the slope level. On these lines are found the projecting or protruding bends of the contour lines. Valley lines are the reverse of ridge lines. They are indicated by the water courses which follow or occupy them. They are the lines of greatest slope when looked at from above and of least slope when looked at from below. On these lines are found all the receding or reentering points of the contour...
Page 171 - In terms of the coordinates 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...
Page 30 - The rodman holds the rod on the starting-point, which may be a peg. a door-sill, or other "bench-mark." He stands square behind his rod, and holds it as nearly vertical as possible. 2. The leveler sets up the instrument, somewhere in the direction in which he is going, But not necessarily, or usually, in the precise line. He then levels the instrument by the parallel platescrews, sights to the rod, and notes the reading, whether of target or speaking-rod, as a
Page 43 - VII. DIFFICULTIES. • (67.) 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 iti the direction of the line, but do not be too particular ; it is a waste of time.
Page 159 - ... Captain Kater. By means of this a station 48 miles distant was observed. The most powerful night signal is, however, Drummond's light. This was invented by Lieutenant Drummond, and consists of a ball of lime about \ in. diameter placed in the focus of a parabolic reflector and raised to an intense heat by a stream of oxygen gas directed through a flame of alcohol. This produces a light eighty times the intensity of an Argand burner. In boisterous and hazy weather this light was brilliantly visible...
Page 154 - ... reports, and to which the personal knowledge of the members of the committee could not be presumed to extend. MEASUREMENTS OF BASES. — There have been measured in all, up to the date of the present report, nine principal baselines, two of which are now connected by a primary triangulation. These two are the Fire Island base, on the south side of Long Island, and the Kent Island base, in Chesapeake bay. Both of these, and also a third one in Massachusetts, were measured with the apparatus designed...
Page 170 - K = distance in yards between two stations, the latitude and longitude of one of which is known, and u" this same distance converted to seconds of arc. L = latitude of 1st station. M = longitude of 1st station, -(- if west. Z = azimuth of 2d station at 1st, counted from the south round by the west, from 0 to 360. The algebraic signs of the sine and cosine of this angle must be carefully...
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 89 - ... of valleys. The former are lines which divide the water falling upon them, and from which it passes off on contrary sides. They are the lines of least slope when looking along them from above downward, and they are the lines of greatest slope when looking from below upward. They can therefore be readily determined by the slope level, etc. They are the lines of least zenith distances when viewed from either direction. On these lines are found all the projecting or protruding bends of the contour...

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