line P t P 3 a ~ (y s y) / (x s x s ) (1 ,7<><> t>i><>) 

 (2,600 1,000) = 1,1 on 1 .01 m - l.l ; and b y, ax f = 

 600 1.1 (1,600) - 1,160. Equation of line P,P 8 is 

 therefore, 



y - 1.1 x + (- 1,160) 

 or y - 1.1 x- 1,160. 



For line P^i 



d - 3V*fe = 9,*'0-0 - 0.4-954 

 XV-XT, 3,250-0 



and 



& = y fi -<*>x fi - o-a>j-o 



making the equation of PjVj 



y 0.4954 x. 



We now compute the co-ordinates of the point A 

 of intersection of PaPa and PiVi. 

 If the equation of the first line be written 



y - ax + b 

 and the equation of the second be written 



y = a' x + b' 

 then the co-ordinates of this common point are : 



and a check is had in the equation 



y -a'x +V 



Substituting numerical values of a, b, a', b', for rou 

 point A, we get : 



v; = 0-(-1, ?6 ) - 7 > je0 ea / 919 



A 1.1-0.4-95* 0.6046 



y A = 1.1(1J3lty + (- t,160)<=951 



We scale the map to get a rough check on the computations. 

 It remains to find for A the station and plus 

 via each ime. 

 The .distance 



log 319 = 2.50379 

 log sin 42 16' = 9.82775 



log 474.8 = 2.67604 

 The logarithmic computation makes P 2 A 474.3. 



10 



