761 



HYDROGRAPHIC MANUAL 



Page 698 



During the plotting of the positions on the smooth sheet, continued reference should 

 be made to the notes in the "Remarks" column of the Sounding Record (see 815) and 

 to the notes that are kept during the progress of the field work from which the De- 

 scriptive Report is subsequently written (see 385). Quite frequently valuable informa- 

 tion will be found in these sources which will guide or influence the plotter during his 

 work. When the plotting of each day's hydrography has been completed, the smooth 

 plotter enters his initials with a colored pencil at the end of the day's entries in the appro- 

 priate space in Stamp No. 38, Processing (fig. 183), to indicate his responsibility for 

 the plotting of that day's work. 



Figure 158. — Protracting three-point fixes with three-arm protractor. 



761. Smooth-Sheet Covers 



To protect the surface of the smooth sheet while the protractor is being used, the 

 entire sheet should be covered with a piece of tracing cloth or heavy tracing paper, 

 otherwise the continual sliding of the protractor over the sheet will soil it excessively. 

 A small round hole, about three-eighths inch in diameter, is cut in the cover over each 

 station, exposing the center to permit accurate plotting. The holes should be cut cleanly 

 so that their edges will not fray out and catch the protractor arms. One method of 

 cutting the holes, after they have been marked in pencil, is by the use of a grommet hole 

 cutter. If the cover is difficult to see through, it is desirable to letter each station name 

 on the cover alongside its respective hole. Positions plotted by protractor are pricked 

 through the cover into the smooth sheet. 



