CHAPTER XX 



SUPPLEMENTAL 



Simplified Metliod of Ship Sounding — Roller Sounding — Sounding 

 Traveller — Sweeping — Vacuiim Tide Gauge Tidal Observations 

 from Ship at Anchor — Plotting — Fixing Positions — Rectangular 

 Co-ordinates — Recent Development. 



SIMPLIFIED METHOD OF SHIP SOUNDING. 



By this method, devised by Captain B. T. Somerville, R.N., 

 and put in practice by him on board H.M.S. Research, many 

 more soundings may be obtained in a given time, and with less 

 labour, than by the ordinary method. 



Fig. 88. » 



Cepth line, % Extra special 

 flexible galmnized wire 



Fore 



^^after j" 



The only lines required are a 1-inch special flexible steel 

 wire fore and after, with |-inch special flexible wire depth-line, 

 both of which are attached to a 112-pound lead slung horizon- 

 tally (see Fig. 88). 



422 



