GENERAL STATEMENT OF THE PROBLEM. 



These are the only observations at hand for combining with the magnificent series of Lieu- 

 tenant Gilliss, according to the method suggested by Professor Gcrling, and contemplated by 

 the expedition. It is impossible to refrain from the expression of deep regret that, from all the 

 observations of the well equipped and richly endowed observatories of the northern hemisphere, 

 so few materials could be found toward rendering available, according to its original purpose, 

 an expedition to which so much labor and enthusiasm had been consecrated, and to which an 

 accomplished observer, already known for the precision of his measurements, had devoted his 

 entire energies during so long a sojourn ; moreover, after the preparation and wide dissemina- 

 tion of ephemerides and charts of the comparison stars for both the planets during the whole 

 period. 



The deduced corrections to Encke's values of the solar parallax corroborated the inferences 

 deducible from the notes, and made palpable the necessity for a recourse to some other method 

 than the desired one of correspondent observations. These corrections, of which the detailed 

 computations will be given, have been found to result as follows, from the correspondent obser- 

 vations already cited : 



CORRECTIONS TO ADOPTED SOLAR PARALLAX RESULTING FROM CORRESPONDENT OBSERVATIONS. 



* 



I. Washington and Santiago. 



Greenwich and Santiago. 



III. Cambridge and .Santiago. 



The large mean error, and striking non-accordance of these results, renders any reliance 

 upon them impossible ; and the only course remaining has been to make use of the largest 



