PREVIOUS CRUISES AND PURPOSES OF CRUISE VII 7 



reaching. For example, the compass-bearing of hnes surveyed 

 in London in 1580 differed 35° from their compass-bearings in 

 1812. 



Besides this, the dream of the mariner had to be abandoned that 

 some day longitude might be determined by simply noting the 

 declination of the compass. This was a great disappointment 

 indeed, for chronometers keeping accurate time had not yet been 

 discovered, and there was no satisfactory method for finding 

 longitude at sea. In fact, there were large prizes offered to any- 

 one who could solve this pressing problem. The only known 

 method was to rely on estimations of each day's run and the course 

 followed; and there were uncharted currents in the ocean which 

 might carry one unawares many miles a day in an unknown direc- 

 tion. Even Halley, the noted astronomer, was three hundred 

 miles out of his reckoning from this cause, on one of his voyages. 



The first to construct a chart showing the declination of the 

 compass was Edmund Halley, whose name is associated in our 

 minds with the great comet. At the expense of the English 

 Government, he sailed over the Atlantic Ocean in the Paramour 

 Pink, between 1698 and 1701, and his cruises were thus the fore- 

 runners of those of the Carnegie. He brought his important 

 work to the attention of the Royal Society by modestly presenting 

 to them "my magnetic chart and some barnacles which I observed 

 to be of quick growth." 



Halley's excellent chart could not be used for finding longitude 

 at sea, since no one knew how much the declination changed from 

 year to year in any one place. Dr. Bauer, the founder of our 

 Department, used to give the following illustration to show the 

 change in the pointing of the compass in the course of time: 



"The Carnegie on her maiden voyage in 1909, in sailing 

 from St. John's, Newfoundland, to Falmouth, England, 

 followed almost the identical path of Halley's Para- 

 mour Pink. The observations on board the Carnegie 

 showed that the variation of the compass as observed by 

 Halley had changed to such an extent that if the Car- 

 negie had followed the same compass-courses as those of 

 the Paramour Pink, instead of coming to anchor in Fal- 

 mouth Harbor, in the south of England, she would have 



