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D OONC # <br /> ---__ <br /> _ CURVE TABLES. 7 <br /> - — ----- -- Published by KEUFFEL 8s ESSER CO. v 7r <br /> HOW TO USE CURVE TABLES. <br /> Table I. contains Tan ° <br /> ----_ _ -_ - Bente and Externals to a 1 curve. Tan.and <br /> - - --- E ttt�o <br /> any other radius may be found nearly enough,by dividing the Tan° <br /> pposlte the given Central ale by the given degree of cure, <br /> - t To find Deg. of Curve, having the Central Angle and Tangenvt: j <br /> Divide Tan.opposite the given Central ale 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 /> r <br /> 7s-7 To find Nat.Tan,#nd Nat.Ex.See.for any angle by Table I.:Tan. <br /> / - or.Ext.of twice the given angle divided by the radius of a V curve will <br /> Y, S �j,� s y� be the Nat.Tan.or Nat.Ex°Sec.-- / 9 z <br /> � ,�. 31 I 06 9 � <br /> EXAMPLE. <br /> - J 1 j - Wanted a Curve with an Ext. of about 12 ft. Angle /�YJ <br /> I ���� ��,� � ! of In <br /> tersection or I. P.=23° 20' to the R. at Station <br /> k 72•dr <br /> Ext.in Tab. I opposite 23°2O o 120.87 <br /> 9 <br /> 120.87+12=10.07. Say a 10 Curve. 7 <br /> --__----- -_-"�"'�' /! �' • J. b b Tan.in Tab. I opp.23 20'=1183.1 <br /> II} 1183.1-+-10=118.31. <br /> y v 1 P f, j ---""correction for A.23°20'for a 10°Cur.=0.16 <br /> )0,4'S_�11�8.31-00.16=118.47=corrected Tangent. <br /> 7 G rl f _ j <br /> corrected Ext.is reuired find in same way <br /> l Ang.23'20'.=23.336-* 10=2.3333=L. <br /> /� /� '�'• �� /U r L 2°19j'-def.for sta.. 542 I. P.=sta. 542 72 <br /> e1°491'= a a a <br /> 70 19j,= a a a +50 Tan.= 1 .18.47 <br /> — 904911= a a a +550 B. C. 41+...l '� 1-- 110401= a a a 543+ L.C.= 2 .33.33 <br /> __ p 9•y� 86.86 E.C.=Sta. 543+86.86 <br /> - 100-53.53=46.47XX(def.for 1 ft.of 10°Cur.)=139.41'= <br /> or /°`1 At J 2°191'=def.for sta.542. <br /> _ Def.for 50 ft.=21 30'for a 10°Curve. ' <br /> - .9J e 8•S '!l Def.for 36.86 ft.=1°501'for a 10°Curve. <br /> LP.An9.23°E0E <br /> —' N <br /> �y J.Yd <br /> - o S ! o io°cur,•. <br /> B M 7. 1 L a , <br /> /a9 ID <br />