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f <br />CURVE- TABLES <br />Published by KEUFFEL 8 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 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.Tabie.I.: Tan. <br />or Ext. of twice the given angle divided by the radius of a l'.. 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 L ;P. =23° 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° 1912'=def. for sta. 542 I. P. =sta. . 542.+72 <br />4° 4912, = a a +50 Tan. = 1 :..18.47 ; <br />70 1911= a a a 543 <br />B. C.=sta. 541 } 53.53 <br />9° 491'= u u+50 <br />11° 40' = " _" " 543+ <br />1 ' C. 2 .33.33 <br />86.86 E. C. =Sta. 543+86.86 <br />100 — 53. 53 = 46.47 x 3'(def. for 1 ft. of 10° Cur.=139.41'.= <br />20 192'=def. for sta. 542: _ <br />Def. for 50 ft. =2° 30' for a 10° Curve. <br />Def. for 36.86 ft. =11 50" for a 10° Curve. <br />a4� .- <br />