66 



The National Geographic Magazine 



for this reason they make it a practice 

 to use the published surveys of other 

 Powers as data for the construction of 

 charts of their own. We are compelled 

 to do likewise, and little by little are 

 utilizing the surveys of those foreign 

 nations, the work of which is known to 

 be reliable. This is a matter of dis- 

 crimination, but experience has shown 

 the necessity for discrimination. Many 

 charts of the Philippines, of Cuba, and 

 of islands of the West Indies have been 

 found to be inaccurate. 



This use of foreign work is not only 

 in the direction of a proper preparation 

 for possible times of national peril, but 

 in the end is a matter of economy. 

 Were this practice not carried on, it 

 would be necessary to purchase our 

 charts from foreign nations — a source of 

 suppty which would be closed to us in 

 time of war — and, when purchased, the 

 corrections made necessary by newly 

 discovered dangers and by changes in 

 buoyage, ranges, lighthouses, etc., 

 would have to be plotted by hand, which 

 is more expensive than making the nec- 

 essary changes on the plate from which 

 the chart is produced. 



AREA COVERED BY OUR CHARTS 



At the present time the Hydrographic 

 Office has in its possession nearly i , 200 

 engraved chart plates and about 50 

 photographic chart plates. These 1,250 

 plates have all been constructed from 

 the results of original naval surveys ; 

 from geographical and cartographical 

 data reported by the commanding officers 

 of vessels in the naval service ; from 

 information collected by the branch 

 hydrographic offices from incoming 

 mariners of all nationalities, and also 

 from the geographical information that 

 comes into the custody of the Navy 

 Department through the prosecution of 

 surveys by foreign governments. 



These charts represent about one- 

 third of what are actually necessary for 

 a complete set of navigational charts of 



the world for the use of the naval and 

 shipping interests of the United States. 



Besides the projecting, drawing, en- 

 graving, photographing, electrotyping, 

 and printing, which constitute the cen- 

 tral work of chart construction and chart 

 correction, the functions of the Hydro- 

 graphic Office embrace all that is kin- 

 dred and contributory to the construc- 

 tion of charts, and hence include the 

 mathematical computations for the pro- 

 jection, the adjustment of triangula- 

 tions, the investigations of the tides, the 

 discussion of observations of the mag- 

 netic elements of the earth in their bear- 

 ing upon charts and navigation, the com- 

 putation of navigational tables, and the 

 designing of instruments and machines 

 for securing maximum of economy. 



Of the 1,250 or more charts that are 

 now available for permanent issue, over 

 300 have been derived from original sur- 

 veys by the U. S. Navy. These, added 

 to the 450 or more charts that have been 

 constructed from surveys by the Coast 

 and Geodetic Survey, make a grand 

 total of 750 or more navigational charts 

 constructed from original United States 

 surveys, a result which places our" people 

 ahead of most of the older countries and 

 in the front rank of the most active na- 

 tions in marine hydrographic work. 



It must not be understood, however, 

 that if we were to become possessed of 

 engraved plates representing the charts 

 now issued by all other nations we 

 would be able to produce navigational 

 charts covering the world's entire water 

 area. Very much remains to be done 

 before the hydrographic features of the 

 world can be so charted as to warrant 

 the statement that dangers to navigation 

 due to lack of knowledge of geographic 

 positions and correct soundings have 

 been reduced to a minimum. 



There are numerous places in the West 

 Indies which we know to be inaccu- 

 rately charted, and this same statement 

 applies to locations in nearly all parts of 

 the world. In the North Pacific Ocean 



