ASTRONOMICAL OBSERVATIONS AND GEOGRAPHICAL POSITIONS. 163 



ginis, and Alpha Leonis, gives 118° 56' 00". Again at Clay Creek, the chronometer 

 gives 116° 09' 13", while by lunar distances it is 116° 05' 45", a difference not great 

 when it is remembered that the chronometer has been transported over 800 miles, and 

 most of the way through a rough country, where there was no road. 



3d. Two sextants made by Gamby (Paris), and one by Wiedemann. All of these 

 were used, simultaneously, by as many observers, in taking an observation for longi- 

 tude by lunar distances. 



The one marked "No. 1," was used by Lieutenant Smith, in all the observations 

 made for time and latitude, and the results obtained from it were very satisfactory. 

 In some cases a set of six pairs of equal altitudes of the sun would be taken, and on 

 computing each pair separately, the greatest difference between any two errors, thus 

 found, would seldom exceed a small fraction of a second ; a proof of the extreme nicety 

 of the observation. 



I am, captain, very respectfully, your obedient servant, 



Lieutenant Tnpor/rapli 'ten! Engineers. 

 Capt, J. II. Simpson, 



Corps Toj/niji-aplutti! Engineers. 



Mr. Major submits results if eai< stations j'or Jongihule. 



Washington, D. C, February 6, I860. 



Dear Sir: I have tlie honor herewith to inclose the essential calculations, and 

 final results of the series of astronomical observations for longitude. 



The transit work requires no explanation; the usual method of discussion having 

 been adopted, so far as the data afforded. 



The lunar distances have been computed by the improved method of Chauvenct, 

 Astronomical Journal, vol. 2, also American Ephemeris, vol. 1. The places of the moon 

 and stars, also other data, are taken from the American Ephemeris, with but one or 

 two instances from the British Nautical Almanac. 



I have to express regret that this work has been delayed, owing to an accident, by 

 wliich the former calculations were destroyed. The inclosed results differ (in most 

 cases very slightly), from those previously deduced on account of using these last as 

 close approximations in the reductions. 

 Yours very truly, 



1). G. Major. 



Captain Simpson, 



Topograph ical JSng ineer 



