104 



NAUTICAL CHART MANUAL 



CURVATURE CORRECTIONS 



Curvature correction = AX 

 (see note) 



Case No. 1 

 (^age 102) 



8.15X 



194 m. 



NOTE: In computing A, use uncorrected latitude of point whose 

 geographic position is being computed. 



TABLE OF CURVATURE FOR 10,000 METERS 



STATE PLANE COORDINATES 



The State Plane Coordinate Grid may be computed and plotted on charts when using U.S. 

 Corps of Engineers blueprints with State Grid control, by one of two methods: 



1. Computing the geographic positions of the State Grid coordinates found on the blue- 

 prints and plotting them on the chart. There are special publications of Plane Coordinate 

 Projection Tables for all states. There is a detailed example of the necessary computations in 

 each. If the number of computations warrant it, the computations may be obtained from 

 the Electronic Computing Division within a few days. The computer is all programmed, so 

 it is just a matter of punching cards for the desired grid intersections, and the time to run them 

 through the computer. 



2. By use of the special publication of Plane Coordinate Intersections Tables (2^ minute). 

 These tables give the Plane Coordinates of every 2)^ minute Geographic Intersection by states. 

 The even 5- or 10,000-foot grid may be measured from the nearest 2K minute intersection 

 by setting, on a pair of dividers, the difference (at map scale) from the 2^ minute intersection 

 value found in the table, and the even 5- or 10,000-foot grid value. Using this value and the 

 2)i minute intersection as a center, swing an arc. The grid line may be obtained by drawing 

 a line tangent to two arcs of the same value. 



