Charting the Dangers of the Deep 



«k! 



Disentangling and measuring the depth of the submerged wire-drag 

 after it has struck an uncharted rock. With the lead Une the 

 discovery of this rock would have been more or less a chance. 

 At left, the buoy or float with the upright and weight attached 



L' 



"AST summer 

 a submerged 

 rock was 

 found at the en- 

 trance to Boston 

 harbor, close to 

 which one or 

 more of our ten- 

 miUion-d o 1 1 a r 

 super-d re ad - 

 noughts had 

 repeatedly passed under the suppo- 

 sition that the water was forty-five 

 feet deep, whereas it was actually only 

 twent>--three feet deep. Before that a 

 rocky pinnacle was discovered in Alaska 

 waters, higher than the Washington 

 monument, lying directly in the steam- 

 ship lane. Only seventeen feet of water 

 covered it. These are striking examples 

 of the valuable service rendered the 

 world's shipping interests by the United 

 States Coast and (".eodetic Survey. 



No one branch of the C.overnment 

 plays a more important part in the wel- 

 fare of the coimtry than the Coast 

 Survey. It is not only the oldest scien- 

 tific bureau in the (iovernment, but the 

 oldest bureau of continuous service. 

 Although its chief work is defined as the 

 making of navigational charts of the 



United States and outlying territory, the 

 Coast Survey gives the man who follows 

 the sea a complete knowledge of the 

 coast, its nature and form, the character 

 of the adjacent sea-bottom, the positions 

 of reefs, shoals and other dangers to 

 na\'igation, the rise and fall of the tides, 

 the direction and strength ot the currents 

 and the character and amount of mag- 

 netic disturbance. 



The chief operation in a hydrographic 

 survey is sounding. A hand line or a 

 sounding machine is used, dcpendingon 

 the depth of the waters, but the compara- 

 tively recent wire-drag, introduced by 

 French hydrographefs and since de- 

 veloped and impnned by the Coast 

 Survey, has re\'olutionized hydrographic 

 surveying. The wire-drag was first used 

 on the Atlantic Coast in 1906, and from 

 that time to the present one thousand, 

 six hundred and sixty square miles have 

 been dragged and about fi\e thousand 

 shoals examined. On the Pacific Coast 

 this work was undertaken in 1914. 

 Probably one-half of the shoals examined 

 had less dei)lh tii.ui charted. 



On a mariner's chart the line of sound- 

 ings with the lead is represented by a 

 row of figures S|)aced more or less closely 

 together, and with tiie rows of numerals 



'204 



