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_ CURVE TABLES:. <br />Published by KEUFFEL 85 ESSER CO. <br />HOW. TO USE CURVE TABLES. <br />Table I. contains Tangents and Externals to a 1° curve. Tan. and <br />— Ext. to any other radius may be found nearly enough, bydividing theTan. <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 fiii& 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 Est. of twice the,given. angle divided by the radius of 'a 1°" curve will <br />be the Nat. Tan. or Nat. Ex. Sec. <br />EXAMPLE. <br />— Wanted a Curve with an Ext. of about 12 ft. Angle <br />of Intersection or 1. P.'=230 20' to the R. at Station <br />542+72. <br />Ext. in Tab. I opposite 23° 20, =120.87 <br />120.87+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. 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°19Y=def. forsta.542 I.P.=sta. 542-72 <br />4° 499 = " " " +50 Tan. = 1 .18.47 <br />--- T 1911= . n . 543. <br />9° 49+}'= . u . +50 - B C. =sta. 541+53.53 . <br />110 40'= '° ° « . 5Q+ L. C.= 2 .33.33 <br />86.86 E. C.=Sta. 543+86.86 <br />100-53.53=46.47X3'(def. ford ft. of 10° Cur:)=139.41'= <br />'20 19;'=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 />