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.1�7 1 34-2- <br />CURVE TABLES. <br />Published by KEUFFEL & ESSFUZ CO. <br />43-7 <br />7 0) 0)9 4- <br />1a <br />HOW TQ USE CURVE TABLES. <br />-2 <br />3 1p 9 <br />Table I. contains Tangents and Externals to a I' curve. Tan. and <br />Ext. to any other radius may be found nearly enough, by dividing the Tan. <br />or Ext. opposite the given Central Angle by the given degree of curve. <br />To find Deg. of Curve, having the Central Angle and Tangent: <br />Divide Tan. opposite the given Central Angle by the given Tangent. <br />To find Deg. of Curve, having the Central Angle and External: <br />Divide Ext. opposite the given Central Angle by the given External. <br />To find Nat. Tan. and Nat. Ex. Sec. for any angle by Table I.: Tan. <br />or Ext. of twice the given angle divided by the radius of a 1' curve will <br />be the Nat. Tan. or Nat. Ex. See. <br />EXAMPLE. <br />Wanted a Curve with an Ext. of about 12 ft. Angle <br />of Intersection or 1. P. =23' 20' to the R. at Station <br />542+72. <br />7 6 1,5 4- <br />42 <br />C7 Z <br />Ext in Tab. I opposite 23' 20' =120.87 <br />126.87 =12 = 10.07. Say a 10P Curve. <br />Tan. in Tab. I opp. 23* 20'=1183.1 <br />1183.1=10 = 118.31. <br />Correc'tion for A. 23' 20' for a 10' Cur. =0.16 <br />118.31+0.16=118.47=corrected Tangent.. <br />(If corrected Ext. is required find in same way) <br />Ang. 23' 20' 23.33* + 10 = 2.3333 L. C. <br />2* 19'2' = def. for sta. 542 I. P.=sta. 542+72 <br />40 491'= CC CC - +50, Tan. = 1 .18.47 <br />70 19',-r= a 99 <br />543 1 <br />90 491 B. C. - sta. 541+53.53 <br />Y 7- +50 L. C-. - 2 .33.33 <br />110 40'- 543+ <br />86.86 E. C. = Sta. 543+86.86 <br />100 - 53.53 46.47 X 3'(def. for I ft. of 10° Cur.) = 139.41'= <br />i - 2'19"=def.for.sta.542. <br />Def. for 50 ft. =20 30' for a 10* Curve. <br />Def. for 36.86 f t. =1' 50j' f or a 100 Curve. <br />dx <br />10* G%LrVG <br />