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THE NATIONAL GEOGRAPHIC MAGAZINE 



granite: columns, TEMPLT5 OS' THE 

 SPHINX, GHIZE;h, EGYPT 



more scientific term is "Lines of Equal 

 Magnetic Declination." 



The first one to construct such a chart 

 was the noted Astronomer Royal of 

 England, Edmund Halley, who, at the 

 expense of the English government, 

 sailed over the Atlantic Ocean on the 

 ship Paranwur Pink between 1698 and 

 1700, and in 1701 published the first 

 "Lines of Equal Magnetic Variation," 

 chiefly, of course, for the Atlantic Ocean. 

 Since then various expeditions have been 

 sent out and new charts have been 

 issued. Of such expeditions, the most 

 recent and extensive was that of the 

 Challenger, 1 872-1 876, again supported 

 by the English government. In fact, to 

 that government and to its various scien- 

 tific bodies must be given the credit of 

 having contributed most hitherto, of any 

 nation, to the advancement of our knowl- 

 edge of the earth's magnetism. One of 

 its most noted scientific men, Prof. J. A. 

 Fleming, thus concludes his excellent ad- 

 dress* on "The Earth, a Great Magnet," 



* Published in the Journal "Terrestrial Mag- 

 netism and Atmospheric Electricity," vol 11 

 1897. 



delivered to the workingmen of Liver- 

 pool, September 10, 1896, at the time of 

 the meeting of the British Association 

 for the Advancement of Science : 



"That great empire which has its cen- 

 ter in these islands, but its dominions 

 scattered over distant seas, has been 

 built up primarily on the art of naviga- 

 tion, in which the magnetism of the earth 

 is a central fact. Neither its world-wide 

 commerce, nor the naval power which 

 defends its coasts, could exist for a day 

 without the aid of the magnetic com- 

 pass." 



THE MAGNETIC SURVEY OE THE EARTH 



But, if so much splendid work has 

 already been done, why is it necessary 

 for the Carnegie Institution of Washing- 

 ton to do so much? From 1905 to 1908 

 it had the brigantine, the Galilee, on the 

 Pacific Ocean, the aggregate length of 

 whose cruises amounted to 60,000 miles. 

 Now it has a specially constructed vessel 

 engaged in magnetic work on the Atlan- 

 tic. Its magnetic observers have already 

 penetrated to nearly every part of the 

 earth — Greenland, Baffin Land, Labra- 

 dor, Newfoundland, British North Amer- 

 ica, Mexico, Central America, Panama, 

 Colombia, Ecuador, the Guianas and 



FOUNTAIN IN THE ALABASTER MOSOUE O^ 

 MOHAMMED AEI, CAIRO, EGYPT 



