7. REPORTS AND MISCELLANEOUS 



263 



be sufficiently accurate for use in computing 

 echo-sounding corrections. 



One diagram is for velocities for the 

 range of temperatures from 0° to 15° C. 

 and the other is for the range of tempera- 

 tures from 15° to 30° C. Both diagrams 

 are used in the same way. Enter the dia- 

 gram with the temperature at depth on the 

 scale at the top of the diagram and drop 

 vertically to the diagonal line representing 

 the salinity, then follow horizontally to the 

 diagonal line representing the depth of the 

 observation, and from here drop vertically 



to the abscissa scale at the bottom of the 

 diagram and read the velocity of sound. If 

 the upper series of depth curves is used the 

 upper of the two velocity scales should be 

 used, but if the lower series of depth curves 

 is used the velocity should be read from the 

 lower of the two velocity scales. 



7-30 Standard widths of lines. — Stand- 

 ard widths of lines are shown in Figure 89 

 by reference to which the draftsman can 

 gage the width prescribed for use in any 

 given class of drafting. A linescope should 

 be used when available. 



10 MILLIMETER - 0.0039 INCH 



. 0.15 MILLIMETER - 00059 INCH 



. 0.20 MILLIMETER = 0.0079 INCH 



. 25 MILUMETER - 00098 INCH 



. 030 MILLIMETER -= 0.0118 INCH 



. 40 MILLIMETER = 0.0157 INCH 



. 050 MILLIMETER = 00197 INCH 



1 0.75 MILLIMETER = 0295 INCH 



1.00 MILUMETER = 00394 INCH 



1.50 MILLIMETERS = 00591 INCH 



t 2 00 MILLIMETERS = 0787 INCH 



Figure 89. — Standard widths of lines. 



