7 



HYDROGRAPHY. 



[Sect, iir. 



station here again, and take a new leading mark. If 

 tlie eye cannot catch a leading object at the moment 

 drop the grapnel to maintain the spot, for much more 

 time is lost by over-running the lines than by coolly 

 waiting for a guide to direct the course. Proceed in this 



manner, running all the soundings in parallel lines or 



nearly so, until the anchorage is all sounded out. 



Having mapped all that is intended to be comprised in 

 the survey, protract the work carefully on board upon a 

 sheet of drawing paper. Draw in the coast hne, rocks. 



shoa 



s, hills, &c., and every other feature from your 

 rough, attending to the hydrographic method of delinea- 

 tion represented in plate A. 



21. The soundings follow next, when reduced to the low 

 water standard of the port by the tide gauge.* If there 

 be no station-pointer on board, protract the angles upon 

 a piece of transparent paper, and mark the stations with 

 their proper numburs. If the soundings have been taken 



equally, divide the spaces between the A 's in as many 

 parts as there are casts, and fill in the corrected sound- 

 ings in the order in which they occur. All soundings 

 which may have been taken when the tide was up and 

 by reduction to low water are dry : draw a line under. 

 very chart-box in the service will be found the abbre- 



I 



n e 



Ch 



No 



viations adopted in Admiralty 



strictly followed, and in Appen 



symbols which will be found useful in taking angles, &c., 



and in other surveying operations ; and in plate A are 



given the usual hydrographic delineations of banks, cliffs, 

 shoals, &c. 



* See Art. 24. 



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