48 Journal of the Mitchell Society [Scptemher 



For curves longer than 100 feet, the tabular values of the external, 

 tangent, and radius must be multiplied, and the degree of curve di- 

 vided, bj^ the ratio of the given curve length to 100. For example, 

 suppose A is 24° and the length of curve to be used is 400 feet, then 



24 

 E = 5.334 X 4 = 21.3, T = 50.744 X 4 = 203.0, D = — = 6°, 



4 

 R = 238.8 X 4 = 955.2. This tables gives conveniently a length of 

 curve that will always be a multiple of ten. The chords therefore 

 will always be an integral number of feet in length. 



Exatnple 1. 



Given A = 40°00'; P. I at Sta. 62 + 11.8 



From Table II, L = 100, E = 9.193, T = 52.135, D = 40°. 



Suppose local conditions are such that E should equal 4G feet 



46 

 approximately. Hence, ratio = — = 5. 



9.2 



L = 500, E = 46.0, T = 260.7, D = S°. 



500 

 = 50 == length of each chord to be applied 10 times. 



10 

 P. I. = 62 + 11.8 



T. = 2 + 60.7 



P. C. = 59 + 51.1 

 L. = 5 



P. T. = 64 + 51.1 



For A ^z= 40°00', the deflections are given directly in Table I as 

 follows : 



Points Deflections 



P. T. A 



1st 40° 29' 



2d 42°29' 



3d 47°58' 



4th 63°41' 



5th (E -= 46.0) n0°00' 



6th 156°19' 



7th 172°02' 



8th 177°31' 



9th 179°31' 



10th P. C. 180°00' 



