

86 



HyUROGKAPHY. 



[Sect III. 



sites of any volcanic islands wliich may have risen and 

 disappeared-"^ 



Bailing along a Coast. 

 28. When sailing along a coast or islands which may 



even be known and charted, it is advisable, as a general 



practi 





r^ 



coast 



"^ 



as the ship sails alon 

 indifferently explored, no opportunity should be omitted 

 of determining as accurately as possible the position of 

 every part within your power* 



The position of places is determined: from a ship with 

 the least disadvantage, by being brought to bear east or 

 w^est when the latitude is taken, and north or south when 

 longitude is observed. And as these observations may 

 be made during several hours of the day,! much may be 



done in a snigle day's run, especially if patent log bases 



connect the stations, and astronomical bearings be em 



ployed. And upon all occasions the noting of transits, 

 or the coming in a line of remarkable objects and of 

 points of interest, should form a necessary portion of 



our duty, although we may believe them to be already 



satisfactorily determined, as they afford the most critical 

 test of the accuracy of former surveys, and are especially 



useful in cases where longitudes of contiguous places 

 may have been had by different observers. 



If time admits of more than this being done, and in 

 some of the countries which are but little explored, it is 



* Set rlso Art. 4, 



t See Rapers Navigation, 830 et eeq., p. 320 j also 834, p< ^^i? 

 second edition. 



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