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THE NATIONAL GEOGRAPHIC MAGAZINE 



representatives now living of the tribes 

 who had made such advancement in the 

 industries and had attained to such vast 

 numbers in the great southwest hundreds 

 of years before the arrival of Columbus 

 in the New World. However, the work 

 is to be continued, and it is altogether 



probable that more extensive excavations 

 and researches will bring to light addi- 

 tional facts hitherto undreamed of. Cer- 

 tain it is that the subject is a most 

 fascinating one, and the great interest 

 recently awakened cannot but be pro- 

 ductive of valuable results. 



HIDDEN PERILS OF THE DEEP* 



By G. R. Putnam, U. S. Coast and Geodetic Survey 



NAUTICAL charts are known to 

 have been in use since the thir- 

 teenth century A. D., but sys- 

 tematic surveying and chart-making date 

 back little more than a century, and most 

 of the information shown on modern 

 charts has been gathered in that time. Of 

 the total area of the earth's surface nearly 

 three-fourths, or about 145,000,000 square 

 statute miles, is occupied by the oceans. 



The charting of this immense area, 

 and particularly of the great lengths of 

 coast line and of the island and reef- 

 strewn portions, is evidently a work of 

 magnitude. To aid in this work is an 

 obligation resting upon all maritime na- 

 tions, not only for the benefit of their own 

 commerce, but for the common good of 

 the world. At present many of these na- 

 tions have made or are extending and 

 perfecting the surveys of their own 

 coasts, and a number of them are adding 

 to the general knowledge of the hydrog- 

 raphy of the seas. 



Great Britain especially has done an 

 immense work in improving the charts 

 of many parts of the world. About eigh- 

 teen nations are publishing nautical 

 charts, and it is estimated that a million 

 copies are issued annually. The British 

 series includes 3,725 different charts, 

 covering practically all oceans and coasts. 



Notwithstanding the amount of work 

 done and the number of charts now pub- 

 lished, but a comparatively small por- 



tion of the continental borders and of the 

 waters of the oceans can be considered as 

 completely surveyed at the present time. 

 Parts of the coasts have been simply 

 sketched by passing vessels, and other 

 areas have been surveyed rapidly to get 

 the information for a preliminary chart. 

 In some cases the original surveys were 

 made to a standard and scale to meet the 

 reasonable requirements of the time, but 

 without counting on the needs of the 

 future, depending on the growth of popu- 

 lation, the building of cities, and the 

 changes in the trend of trade. 



TREMENDOUS INCREASE IN THE SIZE 



OE STEAMERS NECESSITATES 



NEW CHARTS 



With the increase of commerce and of 

 the speed of vessels, more direct routes 

 are demanded for reasons of economy. 

 Inside passages not originally used are 

 sometimes developed for defensive rea- 

 sons. The average draft of the larger 

 vessels has also increased remarkably 

 since the modern hydrographic surveys 

 were commenced, and surveys once made 

 to insure safety for the deepest vessels of 

 that time are no longer adequate. The 

 average loaded draft of the 20 largest 

 steamships of the world has increased as 

 follows: 1848, 19 feet; 1873, 24 feet; 

 1898, 29 feet; 1903, 32 feet. The aver- 

 age length of these vessels was 230 feet 

 in 1848, 390 feet in 1873, 541 feet in 1898, 



* This article is in the main taken from the book "Nautical Charts," by G. R. Putnam, pub- 

 lished by John Wiley and Sons, New York, igo8. Most of the illustrative material is from the 

 work of the U. S. Coast and Geodetic Survey; some of the sketches of Haulover Break are 

 from a paper by F. P. Gulliver. 



