n and plus of A- mlnary Is 



P, P s + P t A - 1 

 The dista 



as computed by logarithms here : 



log 1.919 - 8.28299 

 log sin 68" 39' - 9.95286 



log 2,141 - 8.83068 



The station and plus for A on the location i, 

 then, 21 + 41. 



Scale the map to roughly check these values. 



It is evident that station 21 + 41 on the location 

 survey should coincide with station 21 + 83.3 on 

 the prelimina; 



In cases in practice a check point may be con- 

 veniently obtained by producing: a location tan- 

 gent to intersect the preliminary, and making the 

 computation in the foregoing manner. 



CHECK LINE PC.Pt. When a crossing of the 

 location with the preliminary is not near at hand 

 for a desired check on the field work, a check 

 line, or tie line, is drawn between a chosen point 

 of the location and a chosen point of the pre- 

 liminary; and the bearing and length of the check 

 line are computed. As an example, draw the 

 check line PCPj, and find the bearing by the 

 equation: 



and find the length 



p/ P ~ 



log 470 - 2.07 log 470 - 2.HT 



tog 880 - 2.57978 log sin 51<> O8* - 9.89O81 



log tan 51 08' O.O9282 log 6O4.4 - 2.78129 



We find the bearing and length of PCP? to be 

 N 51 03' E, 604.4 ft. The location having been 

 carried In the field to the point PCt, the transit- 

 man deflects to the left at this point the angle 



^YtPC. - V.P, - W * - 51 (W : : 27 

 and the chalnmen lay off 004.4 on this course, and 



11 



