The Carnegie's Cruises, 1909-10 165 



of a voyage. Thus the magnetic data obtained on the trip from Long Island Sound to 

 Falmouth (September 1-October 18) were communicated, on arrival of the vessel at Fal- 

 mouth October 2, to the leading hydrographic estabhshments of the world, were laid before 

 the Russian Geographic Society at Petrograd by General Rykatchew on October 27, and 

 were pubUshed in Nature on October 28. 



Errors of importance to the na\agator were found on the Carnegie's first cruise. Thus, 

 along the track followed by the Atlantic liners from England to a point off Newfoundland, 

 the magnetic charts, in general, showed too large westerly dechnation (variation of the 

 compass) , the error reaching nearly a degree. From there to Long Island the charts gave 

 systematically too small westerly declination or variation of the compass, by amounts 

 reaching 1 ?5 in the maximum. Owing to the pecuUar and systematic nature of the errors, 

 their effect was always to set a vessel toward Sable Island or Newfoundland, when her 

 course had to be shaped entirely by compass and log, as is the case in time of fog or cloud. 

 Some of the skilled captains of our ocean liners had suspected the possibiUty of such errors, 

 but the Carnegie definitely proved and published the fact and revealed the cause. For 

 long stretches on other portions of the cruise, systematic and, hence, cumulative errors 

 were disclosed, the mariners' charts of the compass direction being found in error at times 

 as much as 2° to 2?5. 



The chart errors in magnetic dip amounted to 1?5 to 2?5, and in the horizontal com- 

 ponent of the Earth's magnetic force the error at times reached nearly one-tenth part. 

 The errors found in the three magnetic elements were partly due to errors in the assumed 

 values of the secular variation. 



The total length of Cruise I was 9,600 nautical miles; the time at sea (not counting 

 stoppages at ports) was 96 days; hence, the average day's run was 100 miles. (See 

 abstract of log and summary, pp. 330-332.) 



CRUISE II. JUNE 1910 TO DECEMBER 1913. 



The alterations and additions found desirable as the result of the first cruise were 

 completed in time to permit the Carnegie to set out from Brooklyn upon a three-years' 

 circumnavigation cruise on June 20, 1910, under the command of W. J. Peters. In con- 

 nection with these alterations, which were almost wholly in the auxihary propulsion plant 

 and its general arrangement, acknowledgment must be made of the cordial and effective 

 assistance rendered by the architect of the Carnegie, H. J. Gielow; by the constructing 

 firm, the Tebo Yacht Basin Company, then under the management of Wallace Downey; 

 by C. D. Smith and W. C. Bauer, consulting engineers; by James Craig, Jr., the builder 

 of the engine; and by D. F. Smith, the engineer-in-charge. 



The Carnegie first proceeded to Greenport, Long Island, and swung ship in Gardiners 

 Bay on June 22, 23, and 25, at the same place as in the preceding year. She was visited 

 and inspected at Greenport by President Woodward in company with the Director. Having 

 completed the determinations of instrumental constants, course was set on June 29 for 

 Vieques, Porto Rico, via latitude 34° north and longitude 46° west. After an unusually 

 favorable passage, during which observations of the tlii-ee magnetic elements were possible 

 on all but two days, Vieques was reached on July 24. Through the courtesy of Superin- 

 tendent O. H. Tittmann, of the United States Coast and Geodetic Survey, opportunity 

 was afforded, at this point, to compare the Carnegie magnetic instruments with the stand- 

 ards of the Vieques Magnetic Observatory, the local observer, G. Hartnell, assisting in 

 every way. The anchorage at Vieques was exposed, so, while the observations were 

 being made at this place, the vessel anchored at Culebra Island, and the observers lived 

 ashore. Upon completion of the comparisons, the vessel returned to Vieques to take on 

 the observers, and then, having made magnetic observations at the Culebra station for 

 secular-variation data, the expedition proceeded to Porto Rico, where valuable assistance 



