Astronomy 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 Occultations and Eclipses. 



H. M. S. 



Walker: From his observations before 1843 5 8 11.14 



Peirce : From the eclipse of 1851 II -57 



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



Peirce: From emersions of the Pleiades, 1856-61 . . I 3- I 3 



From Lunar Culminations. 



s. 



Walker : From Cambridge observations, 1843-45 10.01 



Loomis : From Hudson observations, 1838-44 9.03 



Gilliss : From Capitol Hill observations, 183842 .... 10.04 



Newcomb : From Washington observations, 1846-60 .... 11.06 



Newcomb : From Washington observations, 1862-63 .... 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 13-49 



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- 



