Astrono7ny 



597 



gitude depended on less exact methods. The following table, 

 abridged from Doctor Gould's memoir, gives the differences 

 of longitude : 



GREENWICH OBSERVATORY — WASHINGTON OBSERVATORY, AS DETERMINED 



BEFORE 1866. 



From Occtdtatio7is and Eclipses. 



n. M. 



Walker: From his observations before 1843 5 8 11. 14 



Peirce : From the eclipse of 185 1 ii-S7 



Peirce : From emersions of the Pleiades, 1839. ... ii-45 



Peirce: From emersions of the Pleiades, 1856-61 . , 'i^Z-'^Z 



From Lunar Culminations. 



Walker: From Cambridge observations, 1843-45. . 



Loomis : From Hudson observations, 1838-44 . . . 



Gilliss : From Capitol Hill observations, 1838-42 . 



Newcomb : From Washington observations, 1846-60 . 



Newcomb : From Washington observations, 1862-63 . 



s. 

 10.01 



9-03 

 10.04 



1 1.06 



9.08 



From Transportation of Chronometers betiveen Boston and Liverpool. 



s. 



Mean from 373 chronometers previous to 1849 12.52 



Bond: From 175 chronometers, 1849 11.20 



Walker: From 175 " 1849 12.06 



Bond: From 175 " 1849 12.26 



Bond: From 52 " 1855 1349 



The Superintendent of the Coast Survey, Professor A. D. 

 Bache, determined to take advantage of the Atlantic cable as 

 soon as practicable, and plans for a longitude campaign were 

 made by Doctor Gould. 



The methods employed on land lines required serious mod- 

 ifications in the transatlantic work, and even the Canadian 

 land-lines (Calais, Maine, to Heart's Content, in Newfound- 

 land), could not be worked according to the methods usual in 

 the Survey. The Astronomer- Royal, Professor Airy, had in- 

 tended to make a transatlantic longitude campaign in June, 

 1867; but with his characteristic devotion to science, he en- 



