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CURVE FABLES. <br />Published by KEUFFEL & ESSER CO. <br />HOW TO USE CURVE J.'A MLNS. <br />Table I. contains Tangents and Externals to a 1' 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. See. for any angle by Table I.: Tan. <br />or Ext. of twice the given angle divided by the, radius of a I' curve will <br />be the Nat. Tan.'cr Nat. Ex. Sec:, <br />EXAMPLE. <br />Wanted a Curve with an Ext. of about 12 ft. Angle <br />of Intersection or L. F. =2301 20' to the R: at Station <br />542-1-72. <br />Ext. in cab. I bppositc 23' 20' =120.87 <br />120.57 -12 =10.07. Say a 10' Curve. <br />Tan. in -Tab. I opp. 23°20'=1183.1 <br />1183.1 10 =118.31. <br />Correction for A. 236 20' for a 10' Cut.=0.16 <br />118 31-x-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 z' =def. for sta. 542 I. F. = sta.. 512+72 <br />4' 491' _ °' `:. " +50 Tan. = 1 .18.47 <br />7° 19`- .�, <: u 543 <br />B. C. sta. 54.1-1-•53.53 <br />9' 49:y' _ " " -1-50 2 .33.33 <br />110 40'= " 543+L . C. _ <br />86.86 E. C. =Sta. 543+86.86 <br />100-53.53=4(5.47X3'(def. for 1 ft. of 10-'c, ur.) <br />21 19V=def. for sta. 542. <br />Def. for 50 ft. =2° 30' fora 10' Curve. <br />Def. for 36.86 ft. =1° 50" for a 10' Curve. <br />%Al <br />