to the plotter » the new azimuth is computed and set on the drafting 

 machine to orient the plotter. Then the orthogonal is extended using 

 the right angle-straightedge. Thus there is no loss of time in chang- 

 ing from one method to the other. In beginning the trace of each new 

 orthogonal from deep water, the azimuth on the drafting machine is 

 again set at zero degree; thus the plotter is properly oriented with- 

 out other reference. 



For convenience the proper table of values of Cj^/C_ may be 

 attached to the plotter as shown on the photograph in Figure 2. 



16 



