November 6, 1903.] 



SCIENCE. 



591 



Longitude 



of Transit of Venus 



Pier, Honolulu. 



John Gaetano, 1555, no chronometers, no log g 



Cook, 1785, observatory on Hawaii jq 



Vancouver, 1790, baseil on Cook, various points 



Freycinct, 1819 ^ 



Wilkes, 1840, based on Cook 



LjTnan, 1845-1846, moon culminations, predicted places 



Fleuriais, 1808, 27 moon culminations, first computation 



Fleuriais, 1808, second computation 



Tupman, 1874, 700 culminations, 13 occultations, 540 zenith dis- 

 tances of moon, first computation 



Tupman, 1874, second computation 



Tupman, 1874, combined with first computation of Fleuriais 



Tupman, 1874, combined with second computation of Fleuriais 



Tupman, 1875, 20 chronometers, one trip, Honolulu to San Francisco. 



Hawaiian Government Survey, 1884, chronometers, 2 round trips, 

 Honolulu to San Francisco 



Hawaiian Government, adopted in furnishing time 



Hawaiian Government, adopted for mapping purposes 



23 



31 45 

 45 

 26 

 35 

 15 

 21. 

 25. 



15 

 27. 

 26. 

 26. 

 33. 



Error of 

 Longitude. 



+ 18' 

 + 18 too 



— 1 

 4- 8 

 —12 



- 5.4 



— 1.3 



—12 

 0.0 



— 0.9 



— 0.5 



+ 6.0 



— 1.4 



— 1.2 

 0.0 



In the Spanish chart found by Lord 

 Anson on board the galleon which he cap- 

 tured in 1743, a group of islands was laid 

 down in the same latitude as the Hawaiian 

 Islands, but 17° too far east. 



The southernmost and largest island was 

 named La Mesa, which seems to refer to 

 Hawaii with its high tableland. North of 

 it were La Desgraciada, probably RIaui; 

 and three small islands called Los Monjes, 

 which may have been Kahoolawe, Lanai 

 and Molokai. 



This chart was published in the narra- 

 tive of Lord Anson's voyage in 1749. 



An official letter from the Spanish Ily- 

 drographical Department to the Hawaiian 

 Goveriiinont, dated Madrid, February 21, 

 1865, states that an ancient manuscript 

 chart exists in the archives of that office, 

 in which this group is laid down as in the 

 chart of the Spanish galleon, with the name 

 'Islas de Jlesa,' and a note declaring that 

 they were discovered and named by Juan 

 Gaetano in 1555. 



The large error in the longitude of La 

 Mesa, of 17°, more than 1,000 nautical 

 miles, is not surprising when it is con- 

 sidered that chronometers were not yet 

 dreamed of. that the Spanish navi- 



gators depended entirely on dead reckoning 

 for their longitudes, that the use of the log 

 for measuring the velocity of a ship was 

 not known before 1607, and that the equa- 

 torial current would be effective in pro- 

 ducing an error of the sign actually found. 

 Thus La Perouse, coming from California, 

 found that the error in his dead reckoning 

 caused by this current, when he arrived 

 oii" Hawaii, amounted to 5° to the east, and 

 Vancouver, coming from the south, found 

 a similar error from the same cause, 

 amounting to 5° 14'. 



When Captain Cook discovered Hawaii, 

 in 1768, he was not aware that he had acci- 

 dentally rediscovered La Mesa, and his 

 successors at first retained both La Mesa 

 and the Sandwich Islands on their charts, 

 as may be seen in the atlas accompanying 

 the early editions of Cook 's ' Voyages. ' 



Seven years later, in 1785, two of CookV 

 officers, Portlock and Dixon, on their way 

 to the northwest coast, as their crews were 

 sutTering from scurvy, headed their ships 

 for the supposed position of La I\Iesa, sailed 

 over it, and ran down the parallel of lati- 

 tude till they arrived at Hawaii. A few 

 days later La Perou.se, after searching In 

 vain for La Mesa, did the same, and be- 



