7121 



HYDROGRAPHIC MANUAL 



Page 660 



the configuration of the shorehne, the availabihty of the signals, aad the necessity for 

 controlUng ofi'shore hydrography from shore signals. But the maximum size, which 

 shall never be exceeded under any circumstances, is 42 by 72 inches. 



For projections made in the Washington Office on the projection ruling machine 

 the maximum size of the area on which lines can be ruled and the maximum size of the 

 paper are given in 7327. 



7121. Dog-Ears 



Dog-ears are small drawing paper extensions to the smooth sheet used for including 

 control stations or portions of sounding lines that plot beyond the limits of the sheet 

 unavoidably or tln-ough an error in the original layout. 



Dog-ears must be avoided wherever possible. Eventually they almost always tear 

 off or become so mutilated that they must be removed, and the smooth sheet itself is 

 generally buckled in the process of adding the extension. Extreme care must be exercised 

 in makmg the layout in order to ensure that all the needed control will fall within the 

 limits of the sheet. 



Wliere it is necessary to use a permanent dog-ear, the paper shall be neatly stapled 

 to the smooth sheet with a wire stapler, usmg the minimum number that will ensure 



permanence, and avoiding inter- 

 ference with plotted information. 

 Under no circumstances shall a 

 permanent dog-ear extend more 

 than 6 inches beyond the edge of 

 the sheet. 



If only a single station is to be 

 included, the dog-ear shall be made 

 of tracing paper, temporarily added 

 to the smooth sheet by rubber ce- 

 ment or in any other way which 

 will not damage the sheet. Three 

 fine inked lines shall be drawn on the smooth sheet toward the station on the dog-ear, 

 of such lengths and azimuths as will permit relocating the station in the future on another 

 temporary dog-ear, should that become necessary. Each such line shall be marked 

 thus: "to A MARKO" (see fig. 143). 



713, Auxiliary Plotting Sheets 



Grained or painted aluminum sheets and drawing paper mounted on aluminum 

 sheets are occasionally useful as accessories to the smooth sheet for — 



(a) Plotting and adjusting the positions of survey buoys located by any of tlie methods described 

 in section 25, when plotting is preferable to computation. For exanjple, where the computations are 

 too involved, as in the case of cuts obtained from a vessel whose position is determined by a three- 

 point fix (see 2514 and 2552) ; where buoys are located by taut-wire distances; or where they are located 

 by subaqueous sound ranging. 



(6) Plotting and adjusting hydrographic positions located by; dead reckoning, astronomic sights, 

 R.A.R., and combinations of these. 



In all cases in which aluminum sheets are used as intermediaries the final results 

 must be transferred to the smooth sheets; in the case of control, by dms. and dps. 

 (see 7411); and in the case of hydrographic positions, either by dms. and dps. or by a 

 tracing-paper transfer similar to that described in 7413. As finally plotted, the smooth 



Figure 143. — Temporary dog-ear for smooth sheet. 



