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CURVE TABLES <br />= <br />f <br />¢, <br />Published by KEUFFEL & ESSER CO. <br />HOW TO USE CURVE TABLES <br />+: <br />Table I. contains Tangents and Externals to a 1° curve. Tan. and <br />t. to any other radius may be found nearly enough, by dividing the Tan. <br />r 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 />ivide Tan. opposite the given Central Angle by the given Tangent. <br />To findDeg. of Curve, having the Central Angle and External: <br />)ivide 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 />t Ext. of twice the given angle divided by the radius of a 1° curve will <br />e the Nat. Tan. or Nat. Ex. Sec. <br />EXAMPLE <br />p <br />Wanted a Curve with an Ext. of about 12 ft. Angle <br />of Intersection or I. P.=230 20' to the R. at Station. <br />a' <br />542+72. <br />l <br />j <br />' <br />Ext. in Tab. I opposite 23° 20'= 120.87120.87-12=10.07. Say a 10° Curve. r <br />Tan. in Tab. I opp. 23° 20'= 1183.1 <br />i <br />1183.1=10=118.31. <br />e1 <br />Correction for A. 230 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"=.def. for sta. 542 I. P. =sta. 542+72 <br />4° 491' _ x-50 Tan. = 1 .18.47 <br />7°19'= " " " 543 <br />9° 49' _ 50 B. C. =sta. 541+53.53 <br />11° 40'= « " ° i L. C. = 2 .33.33 <br />4 86.86 E. C. = Sta. 543x--86.86 <br />100-53.53=46.47X3'(def. for 1 ft. of 10° Cur.)=139.41'= <br />2° 192'=def. for sta. 542. <br />Def. for 50 ft. =2° 30' for a 10° Curve. <br />Def. for 36.86 ft. =1° 50j' for a 10° Curve. <br />i <br />i <br />sr <br />x� <br />I.P.An9.23•201 <br />N ' <br />p1 is9j <br />. - <br />\ xJ x <br />