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5 <br />77 <br />CURVE TABLES. <br />. <br />Published by KEUFFEL & ESSER CO. <br />..HOW TO USE CURVE TABLES. <br />H <br />Table I. contains Tangents and Externals to a 10 curve. Tan. and <br />Tan.- <br />® <br />6,a0 <br />�` <br />Ext. to any other radius may be found nearly enough, by dividing the <br />a, <br />or Ext. opposite the given Central Angle by 4.he given degree of curve. <br />Tangent: <br />To find Deg.. of Curve, having the Central Angle and <br />o� <br />Divide Tan. opposite the given Central Angle by the given,Tangent. <br />Curve, having the Central Angle and External: <br />To find Deg. of <br />Divide Ext. opposite the given Central Angle by the given External. <br />{ <br />To find Nat. Tan. and Nat. Ex. Sec. for any angle by Table L: 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 />1� <br />4).5 <br />Wanted a Curve with an Ext. of about 12 ft. Angle <br />of Intersection or I. P.=230 20' t©, the R. at Station <br />542+72. <br />'' <br />Ext. in Tab. I opposite 23° 2,d =120.87 <br />srh1 <br />120.87=12=10.07. Say a 10° Curve. <br />Tan: in Tab. I.-opp. 23'2V=1183.1, <br />1183.1-10=118.3L. <br />I' <br />Correction for A. 23°.20' for a 10° Cur. =0.16 <br />F <br />Qr� <br />118.31-0.16=11$.47=corrected Tangent. <br />a <br />(If corrected Ext. is required find in same way) <br />C. <br />Ang.23°20:=23.33°=10=2..3333=L. <br />s2° <br />19 def. for sta. 542 <br />« <br />I. P.—sta. - 542 k 72 <br />1 <br />4. 4� �, = s, . +50 <br />Tan. = .18.47 <br />�11-- <br />7° 193 _ aa ',a 543 <br />B. C, a- sta. 541- 53.53 <br />4912'= < +50 . <br />L. C. — 2 .33.33 <br />q <br />11° 40'= " 11 " 543+ <br />I. <br />—. <br />86.86 <br />E. C.—Sta. 543+86.86 <br />-- <br />$e� <br />�oG_caai. <br />100-53.53=46.47X3 (def. for 1 ft. of 10' Cur.) =139.41'= <br />P4 <br />def. for sta. 542.' <br />%L <br />Def.4or 50,ft. =20 30' for a 10° Curve. <br />Def. for 36.86 ft. =1° 502' fora 10°• Curve. <br />.7 <br />a <br />*o4 <br />r�.P.n�9.zs^zo <br />N Iy <br />--- <br />_ - - -- <br />- I0, Curve <br />_ <br />a m1 <br />I3ig <br />*. <br />