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Sect. III.] 



HYDROGRAPHY. 



87 



extremely desirable that no opportunity sliould be lost of 

 perfecting their outline, the heavy boat? may be hoisted 

 out and sent in shore of the ship to run in the coast line 

 and the detail whilst the ship carries on a triangulation 

 and continuation of bases in the distance, making what 

 may be termed a running survey. 



Running Survey 



Whenever 



distance of 4, 5, or 6 miles at starting, and let them and 

 the ship anchor, if possible, to measure a base by sound 



to 



(Art. 19), and to get astronomical bearmgs and ar 

 the same points. Fix the ship's position by repeated 

 observations for the latitude and by chronometer ; then 

 weigh and put the patent log over and steer a steady 



course alon 



( 



admit of it, without stopping). One boat now runs along 

 the land from point to point, putting in the coast line 

 and its detail, getting astronomical bearings and angles 

 as she proceeds, especially of all transits of points and 

 headlands, and measuring her distance between them by 

 patent log, and sounding, but without stoppinsr. The 



other boat attends principally to the soundings, fixing 

 herself as she requires, by angles and bearings between 

 the points determined by the other "boat and the ship. 



At the end of a few miles' run, or at noon, or when 

 necessary to renew the angles and bearings, a signal is to 

 be shown and the logs are then to be hauled in and 

 read off, but not reset, fresh angles and bearings to be 

 taken and a new base commenced, the distance between 

 the ship and boats being again measured by sound. The 



