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6Z X32.0 <br />3 �/ x`46 /. <br />•a <br />O 0 <br />r '' <br />-•X <br />e <br />' <br />a <br />I <br />• <br />.�q�..-.S` ' <br />s <br />rq <br />(J I., �.� �/ � �Z fib <br />�,p 9�S' <br />� � I <br />• <br />`j' <br />I <br />t <br />1 <br />0 <br />I <br />1e <br />J826, 13zS,S <br />19,'6'1 13 2s S 6°7,IL � <br />Z. �j 778 , / <br />CURVE TABLES." r <br />Published by KEUFFEL & ESSER CO. <br />HOW TO USE CURVE TABLES <br />Jfo -on. <br />156- 20' <br />199�f�' <br />l2 <br />Table I. contains Tangents and Externals to a 1° curve. Tan. and <br />Ext. to any other radius may be f ound nearly enough, bydividing theTan. sz/, <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. 3Z/, <br />or Ext. of twice the given angle divided by the radius of a 1° curve will /43,5 <br />be the Nat. Tan. or Nat. Ex. Sec. <br />EXAMPLE. <br />Wanted a Curve with an Ext. of about 12 ft. An.-i-- <br />of <br />noof Intersection or 1. Y.=230 20' to the R. at Station. <br />542+72. <br />Ext. in Tab. I opposite 23° 20' =120.87 <br />420.87-- 12=10. 07. Say a 10° Curve. <br />Tan. in Tab. I Opp. 230 20' =1183.1 2 <br />. 1153.1=10=118.31. <br />Correction for A. 23° 20' for a 10° Cur. =0.16 <br />118.31-{-0.16 =118.47 =corrected Tangent. 2 <br />(If corrected Ext. is required find in same way) <br />2° 19:1V= def. for sta. 542 1. 1'. = stn.. 542-x-72 <br />4° 49"= " (( (' SI <br />+50 Tan. = 1 .18.47 <br />9° 491' _ (� Q0 /( -}-50 B. C. =stn. _ 541 -I-53. 53 21 <br />110 40'.= °` (' '° 543+ L. C. = 2 .33.33 <br />86.86 E. C. = Sta. 543+86.86 <br />100-53.53=46.47X3'(def. for 1 ft. of 10° Cur.) =139.41'= <br />2° 191'=def. for sta. 542. <br />Def. for 50 ft. =2° 30' for a 10° Curve. <br />Def. for 36.86 ft. =1' 501' for a 10° Curve. <br />i <br />1 _ 1 <br />N r� <br />10° Curve <br />xr <br />``W Q0i <br />t _ <br />