514 THE POPULAR SCIENCE MONTHLY. 



the islands shown on the present charts with queries, in regions not 

 yet sufficiently explored, will prove to have been similarly misplaced 

 at that early date. 



The science of hydrography, by which the correct establishment 

 of positions and exact delineations of the shores are attained, I'eniained 

 meagre until the middle of the eighteenth century, when it may be 

 said to have fairly commenced with the expeditions of Captain James 

 Cook under the auspices of Great Britain, which were soon followed 

 by similar undertakings by other nations, especially by France and 

 Russia, and at a later period by the United States. Almost all these 

 voyages of discovery and explorations were of circumnavigation, and, 

 though many localities were examined more or less in detail, in gen- 

 eral they could only result in skeleton charts to be filled in by sys- 

 tematic surveys, at a future period, conducted under the direction of 

 organized institutions. In the first quarter of the present century 

 hydrog^aphic offices were established by the principal maritime na- 

 tions for the survey of their waters at home and in their colonies. To 

 the hydrographic office of Great Britain, which has been liberally 

 provided with means by the Government, belongs the credit of hav- 

 ing taken the lead in extending systematic surveys into almost every 

 water traversed by vessels, and to its zeal and energy all navigators 

 and commercial communities will ever be deeply indebted. At pres- 

 ent almost every nation having a seaboard has it hydrographic office 

 for the survey of its own coast, and to participate in the survey of 

 such waters as are considered the common possession of nations, and 

 of the coasts of countries which do not provide for surveys. Almost 

 every European nation has provided for the trigonometrical survey 

 of its entire domain. 



The British Ordnance Survey, commenced in 1*783, will probably 

 take ten years yet to complete ; the trigonometrical surveys of 

 France, Germany, the Netherlands, Belgium, and the European por- 

 tion of Russia, are in course of completion ; in other countries they 

 are in progress. The several governments have also agreed on meas- 

 ures for the careful connection of the triangialations across the bor- 

 ders of their states. Where such rigid geodetic operations were 

 instituted previous to the hydrographic survey of the coasts and wa- 

 ters, they furnish the hydrographic surveyor, not only with the correct 

 outlines of the coast, but also with the precise position of the land- 

 marks upon which he may base his work, or, in other words, a skele- 

 ton for the same. But, when such surveys are not existing, he is com- 

 pelled to lay down the coast-line also, with its detail as far inland as 

 there are landmarks auxiliary to navigation, thus performing the 

 labors of the topographer as well as those of the hydrographer. 

 Both require the greatest care, for on the precise establishment of the 

 landmarks depend in a great measure the delineation of the shore- 

 line, the establishment of outlying dangers, and the exact location of 



