Memoir of Frank Russell Firth

Front Cover
Lee and Shepard, 1880 - 143 pages
 

Contents

SECTION
12
Leveller
13
Rodmen
14
The level
15
The clinometer
16
Transit points
17
Obstacles to alignment and measurement
18
General problem
19
Lines at a large angle
20
SECTION
24
Choice of routes
55
Resistance due to grade
61
Train load reciprocals
67
Comparison of routes
75
SECTION
77
Establishing grade lines
81
Central angle and length of curve
87
Formula for external distance
93
Deflection angles
101
Selection of angles 21
104
Ratio of correction to excess of
107
By offsets from the chords produced
113
By tangent offsets
119
SECTION PAGE 173 To find a new P C C and last radius R for new direction of tangent through same P T
124
Do beginning with any subchord
125
To replace a simple curve by a threecentred compound curve between the same tangent points
127
To find the distance between the middle points of a simple curve and threecentred compound curve
129
To pass an obstacle on a curve
131
The curve sharpened at the tangents
132
To replace a tangent by a curve compounded with the adjacent curves
134
When the perpendicular offset p is assumed
136
To find a new radius for a parallel tangent
137
Locus of the centre 02
138
To find new tangent points for two parallel tangents
139
To replace the middle arc of a threecentred compound by an arc of different radius
140
When the radius of the middle arc is the least
141
When the radius of the middle arc is intermediate
142
To find new radius for a given radial offset
145
CHAPTER VII
147
Single turnout from straight track in terms of frog angle
148
Single turnout from straight track in terms of frog number
149
To find new radius from same P C for new position of
151
Double turnout middle track straight and three given frogs
152
Double turnout on same side of straight track to calculate the middle frog F
153
Double turnout on same side of straight track with three given frogs
155
Definition
157
b When the middle track is straight beyond F
158
When the middle track is reversed at F
159
Turnout on the inside of a curved track
161
AB VAB VBA and R₂ to find A A and R₁
163
Tongue switches
164
Tongue switch double turnout to find F
165
Tongue switch double turnout with three given frogs
166
Tongue switch double turnout on same side of straight track with three given frogs
167
b The middle track compounded at F
168
To find a new P C C for a parallel tangent
169
To find the connecting curve from frog to parallel siding on a curve in terms of F and perpendicular distance p
170
To find new P C and new radius for a parallel tangent
171
To locate a crossing between parallel tracks
172
To locate a reversed curve crossing between straight tracks
173
To locate a reversed curve crossing between curved tracks
174
Profiles
184
Simple levelling test levels
185
Errors due to curvature of the earth
186
Errors due to refraction
187
Levelling by transit or theodolite
188
To find the H I by observation of the horizon
189
Stadia measurements horizontal sights
191
Stadia measurements inclined sights vertical rod
193
Stadia measurements inclined sights inclined rod
195
CHAPTER IX
196
Clearing and grubbing
197
Cross sections formulæ for
198
Cross sections staking out
200
Cross sections on irregular ground
201
Compound cross sections
203
Form of crosssection book
204
Extended cross profiles
205
Isolated masses
206
Officework
207
Drains and culverts
208
Arch culverts
209
Foundation pits Bridge chords on curves
210
Cattleguards
214
Location Alignment Shafts Curves Levels Grades Sections Rate of progress Ventilation Drain age
216
Retracing the line
222
Side ditches and drains
223
CHAPTER X
225
Formulæ for sectional areas
227
Prismoidal formulæ for solid contents
229
Tables of equivalent depths
231
Formula for equivalent depth in terms of slope angle
232
Conditions necessary for correct results in use of tables
233
Exact calculation of context examples
234
Wedges and pyramids
236
Sidehill sections irregular ground
237
Systems of diagrams
238
Correction for curvature in earthwork
239
Haul Centre of gravity of prismoid
243
Final estimate
245
Monthly estimates
246
SECTION PAGE
247
The theodolite
253
Geometrical Propositions
270
Trigonometrical Formulæ
273
Curve Formulæ 277
3
Middle Ordinates for Rails 304
xii
Grades and Grade Angles 305
xiv
Barometric Heights in feet 307
Coefficient of Correction for Atmospheric Temperature 309
Coefficient for Reducing Stadia Measurements 310
Minutes in Decimals of a Degree 313
Inches in Decimals of a Foot 314
Squares Cubes Roots and Reciprocals 315
1
Rocky shores Tielines 22
22
System of plotting map 23
23
Logarithmic Sines Cosines Tangents and Cotangents 359
24
Natural Sines and Cosines 449
45
Natural Tangents and Cotangents 458
54
Natural Versed Sines and External Secants 470
61
Useful Numbers and Formulæ 498
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Page 204 - A + 75 it is -f^M; and the same for corresponding points on the other side of B. The corrections in the case shown are subtractive, since M is negative. They are additive when M is positive, and the curve concave upward.
Page 261 - To find the angle or arc corresponding to a given logarithmic sine, tangent, cosine, or cotangent. — If the given logarithm is found in the proper column take out the degrees and minutes directly; if not, find the two consecutive logarithms between which the given logarithm would fall, and adopt that one which corresponds to the least number of minutes; which minutes take out with the degrees, and divide the difference between this logarithm and the given one by the adjoining tabular difference...
Page 208 - ... feet below grade. The embankment is protected at the upper end of the drain by a bit of vertical wall, enclosing the end of the pipe. If necessary, a paved gutter may lead to it. Where stone abounds, the bed of a dry ravine may be partly filled with loose stone, extending beyond the slopes a few feet, which will prevent the accumulation of water. When the flow of water is estimated to be too great for two lines of the largest pipe, a culvert is required.
Page 258 - ... of the calculation. By this rule we have Number Logarithm 1.384 0.141136 .1384 9.141136 .01384 8.141136 .001384 7.141136 etc. etc. No confusion need arise from this method in finding a number from its logarithm; for although the logarithm 6.141136 represents either the number 1,384,000, or the decimal .0001384, yet these are so diverse in their values that we can never be uncertain in a given problem which to adopt.
Page 258 - ... number are given in the first column, the fourth at the top of the other columns. The first two figures of the mantissa are given only in the second column, but these are understood to apply to the remaining four figures in either column following, which are comprised between the same horizontal lines with the two. If a number (after cutting off the ciphers at either end) consists of not more than four figures, the mantissa may be taken direct from the table ; but by interpolation the logarithm...
Page 263 - Find in the. proper column two consecutive logarithms between which the given logarithm falls. If the title of the given function is found at the top of that column read the degrees from the top of the page; if at the. bottom read from the bottom. Find the value of (q...
Page 261 - The above rules do not apply to the first two pages of this table (except for the column headed cosine at top) because here the differences vary so rapidly that interpolation made by them in the usual way will not give exact results. On the first two pages, the first column contains the number of seconds for every minute from 1...
Page 262 - These two pages may be used in the same way when the given angle lies between 88° and 92°, or between 178° and 180°; but if the number of degrees be found at the bottom of the page, the title of each column will be found there also; and if the number of degrees be found on the...
Page 185 - ... reading, proportional to the distance of the rod from the instrument. But the errors being equal for equal distances, and the backsights and foresights having opposite signs in our calculations, the errors cancel when the distances are equal. Hence, to avoid errors in elevation, each new...
Page 261 - ... fourth are the last three figures of a logarithm which is the difference between the log sin and the logarithm of the number of seconds in the first column. The first three figures and the characteristic of this logarithm are placed, once for all, at the head of the column. To find the log sin of an arc less than 2° given to seconds. Reduce the given arc to seconds, and take...

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