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, 1�0 -A, <br />- t"CURVE TABLES. <br />_ Published by KEUFFEL & 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 otl er radius may be found nearly enough, by dividing the Tan. <br />or Ext. opposite the given Central Ankle 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. Sec. <br />EXAMPLE. <br />Wanted a Curve with an Ext. of about 12 ft. Angle <br />of Intersection or I. P. =23° 20' to the R. at Station <br />_ 542-j 72. <br />Ext. in'Tab. I opposite 23' 20' =120.87 <br />_ <br />120.87--1,2=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=118A7 =corrected Tangent. <br />(If corrected Ext. is required find in same way.) <br />Ang.23°20'=23.33'=10=2.3333=f.. C. <br />_ 2' 19 V = def. for sta. 542 1. P. = sta. .542+72 <br />40 49I' = " " +50 Tan. = 1 .18.47 <br />70 1912-1 543 B. C.=sta. 541+53.53 <br />904911 ' _ " 1 50 _ <br />11' 40'= " " " 543+ I C' 2 .33.33 <br />j' 86.86 E. C.=Sta. 513-'86.86 <br />— ` 100-53.53=46.47X3'(def. for 1 ft. of 10' Cur.)=MAI'= <br />I 2° 19,'=def. for sta. 542. <br />Def. for 50 ft. =2° 30' for a 10° Curve. <br />{ Def. for 36.86 ft. =1° 50-11 for a 10' Curve. <br />—i <br />1 <br />