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I <br /> i - - - - - --=- CURVE FABLES. <br /> Published by KEUFFEL & EMR CO. <br /> ------ - _ -- __ _ .------- __ HOW TO USE CURVE FABLES. <br /> Table I: contains Tangents and Externals to a 1°curve. Tan.and <br /> F Ext.to any other radius may be found nearly enough,by dividing the Tan. <br /> Or Ext.opposite the given Central Angle by the given degree of curve. <br /> To find D h 1 <br /> 1 Deg. of Curve, having t e Centra Angle and Tangent: <br /> - <br /> Divide Tan.opposite the given Central Angle by the given Tangenrnt. <br /> find.Deg. of Curve, having the Central Angle and Exteal: <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.Anile <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 oppp 23°20'=1183.1 <br /> 1183.1-1-10=118.31. <br /> Correction for A.23°20'for a 10°Cur.-0.16 <br /> 11&31+0-16-11&A7-corrected Tangent. <br /> (If corrected Ext.is re <br /> cauired find in same way) <br /> Ang.23°2(Y=23.33 +10=2.3333=L.C. <br /> 2°19}'=def.for sta. 542 I. P.-sta. 542-x-72 <br /> I 4°.4911= v ° " +50 Tan.= 1 .18.47 <br /> ---- -- - 4 - - -- -- 70 1911= 543 <br /> 9°49}'= a a a +50B. C.=sta. 541+53.53 <br /> ----_+ _ <br /> -t--- -- — = 11°40'-* a r a L.C.= 2 .33.33 <br /> 543+ <br /> _ 86.86 E.C.=Sta. 543-X88:86 <br /> -- 100-53.53-46.47X3'(def.ford 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°50j'for a 10°Curve. <br /> � .An9.Y3•YO� • <br /> _ � _ 10•CurN <br /> _ ` <br /> % �i <br /> -- <br />