84 



HYDROGRAPHY. 



[Sect. lit. 



exists, also raise the level there, so that vcbsek which 

 cannot enter during the dry season are at such times ' ^ - 



to pass over the bar. 



biiri 



,s 



to rise, when it attains its maximum, when it begins to 

 subside and regains its mean or ordinary level, should be 

 carefully noted, and with it the elevation of the water in 

 feet, both in its ascent and descent. 



Discovery of Land. 



On 





the first endeavonFj after the vessel is placed in safety, 



bllOil 



as 



as 



the means of observation admit, and not to quit the 

 spot until the danger is satisfactorily placed upon the 

 chart.* Describe it as accurately as you can ; detei^.ine 

 its extent, height, and configuration ; the adjacent sound- 

 ings, and the quality of the ground ; and give a sketch 

 of its outline. If it be extensive, a running survey will 



t If it be 



within sig 



5 



it 



* 



.^ 



position must be fixed by bearings or angles between 

 known points of the coast, and some conspicuous objects 

 upon the land selected, which being hronght in a line 

 will lead ships clear of the danger. Do this for t^^^h 

 sides, and give correct bearings of the transits, and, if 

 possible, sketches of the objects. 



F 



* See Raper's ^ Navigation/ 855, d. 328; and 856, p. 329. *'No com- 

 mander of a vessel/' observes that talented oflScer, " who might meet 

 miexpectedly any danger (before unknown), could be excused, except by 

 urgent circumstances, from taking the necessary steps both for ascer- 



taiuing Its true position and for giving a description as complete as a pru- 

 dent regard to his own safety aUowed/' 

 t See Ait. 29, 



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