Image from the Biodiversity Heritage Library.
Contributed by Yale Peabody Museum of Natural History.
| www.biodiversitylibrary.org
Transcription
CURVE TABLES.
Published by KEUFFEL & ESSER CO.
HOW TO USE CURVE TABLES.
Table I. contains Tangents and External to a 1° curve. Tan. and
Ext. to any other radius may be found nearly enough, by dividing the Tan.
or Ext. opposite the given Central Angle by the given degree of curve.
To find Deg. of Curve, having the Central Angle and Tangent:
Divide Tan. opposite the given Central Angle by the given Tangent.
To find Deg. of Curve, having the Central Angle and External:
Divide Ext. opposite the given Central Angle by the given External.
To find Nat. Tan. and Nat. Ex. Sec. for any angle by Table I.: Tan.
or Ext. of twice the given angle divided by the radius of a 1° curve will
be the Nat. Tan. or Nat. Ex. Sec.
EXAMPLE.
Wanted a Curve with an Ext. of about 12 ft. Angle
of Intersection or I. P. =23° 20' to the R. at Station
542+72.
Ext. in Tab. I opposite 23° 20'=120.87
120.87÷12=10.07. Say a 10° Curve.
Tan. in Tab. I opp. 23° 20'=1183.1
1183.1÷10=118.31.
Correction for A. 23° 20' for a 10° Cur.=0.16
118.31+0.16=118.47=corrected Tangent.
(If corrected Ext. is required find in same way)
Ang. 23° =23.33°÷10=2.3333=L. C.
2° 19½'=def. for sta. 542 I. P.=sta. 542+72
4° 49½'=" " " +50 Tan.= 1 .18.47
7° 19½'=" " " 543 B. C.=sta. 541+53.53
9° 49½'=" " " +50 L. C.= 2 .33.33
11° 40'=" " " 543+ E. C.=Sta. 543+86.86
86.86
100-53.53=46.47×3'(def. for 1 ft. of 10° Cur.)=139.41'=
2° 19½'=def. for sta. 542.
Def. for 50 ft.=2° 30' for a 10° Curve.
Def. for 36.86 ft.=1° 50½' for a 10° Curve.