Page 853 miscellaneous 9336 



omitted. In general the cartographer should be guided in omitting overlapping soundings by the 

 same rules as when inking soundings on coinciding or closely spaced adjacent lines. 



Do not transfer bottom characteristics from an overlapping sheet, unless the latter is to be super- 

 seded. 



Where comparative soundings occur within the overlapping area, transfer only one of each pair 

 of soundings. It is immaterial which one is transferred, but if it is the vertical cast, omit the letters 

 "VC". 



Transferred soundings should always be in color. Red, blue, and green are the preferred colors. 

 It is permissible to use the same color for overlaps from two different sheets provided the sheets are 

 not contiguous. For example, red can be used for overlap at the top and bottom of a sheet. 



The notation "JOINS H- " should always be placed just outside the limits of the hydrography 



and in the same color as the transferred soundings. A similar notation should be placed on the sheet 

 from which the overlap was taken. Where adjoining surveys have been registered but not verified, 

 such notations should be made in pencil. These notations should be made with the Leroy lettering 

 set, using No. 100 template (slanting letters). 



Soundings from overlapping sheets are to be shown only to just outside of the limiting line of 

 soundings on the principal sheet. Where no actual overlap exists between the two sheets, only the 

 nearest line of soundings need be transferred. 



Where the scales of the two adjoining sheets are the same, soundings are to be transferred by the 

 tracing-paper method. Where the scales are different and the lines regular, proportional dividers, or 

 a projector, should be used for making the transfer. The ends of straight portions of lines can be 

 transferred by proportional dividers and intermediate soundings filled in with the spacing dividers 

 either from the sheet proper or from the Sounding Records. Where the lines are irregular a projector 

 shall be used, or a photostat of that portion of the sheet should be made to the desired scale and the 

 soundings transferred by the tracing-paper method. 



Where an enlargement of more than twice needs to be made, the overlapping soundings should be 

 plotted directly on the sheet if the control is available. Otherwise the enlargement should be made 

 by projector, by photography, or by proportional dividers, whichever is more economic, great care 

 being taken in such cases when using the latter method. 



Wherever overlap is transferred, the curves on the two sheets should be made identical in the 

 overlap. 



Where a sheet is surrounded by a number of sheets, always show all overlaps on one sheet, where 

 possible to do so. Where the scale is the same on overlapping sheets the overlap should be placed on 

 the inshore sheet. 



9336. Depth Curves 



The depth curves shall be drawn lightly in pencil by ^he verifier in accordance with 

 7762 and, after they have been aj)proved, they shall be inked in the standard colors given 

 in table 27 in accordance with 7763. In general, all applicable curves given in the table 

 shall be inked, except those marked "omit," which are only to be used where needed 

 to delineate submarine relief that might otherwise be overlooked. All curves not 

 inked shall be erased. (See also 93426.) 



9337. Confidential Sheets and Records 



Survey sheets and records of a confidential nature are plainly stamped "Confiden- 

 tial" when they are received at the Washington Office. They are kept in locked com- 

 partments in the vault in the Division of Charts and are removed therefrom only on 

 approval of the Chief or Assistant Chief of the Division of Charts. They must be 

 replaced in the locked compartments each evening before the close of the day's work. 

 Insofar as practicable any work requiring their use shall be completed within one 

 working day. 



Confidential sheets and records are to be reproduced only as approved by the Chief 

 or Assistant Chief of the Division of Charts. Negatives made in reproduction shall be 

 destroyed immediately afterward. Reproduction copies sent out of the Office are to 



