Astronomical Operations at the Pulkova Observatory. 93 



observations of right ascension, and 0"-357, according to those of 

 declination, with a probable error of 0"-036. This agreement, for 

 two values entirely independent of each other, is remarkable. 

 Their mean gives 0"-339, with a probable error of 0"-025. 



If we admit with Struve 0"-2ll for the hypothetical value 

 which may be assigned to the parallax of a star of the first mag- 

 nitude, or to the angle which the radius of the earth's orbit sub- 

 tends from this star in a direction perpendicular to the visual ray, 

 it follows that the annual motion of the centre of gravity of the 

 solar system in the same direction, would be a little more than 

 once and a half this quantity, (1-54,) or about fifty-three millions 

 of leagues of twenty-five to the degree, (147,000,000 of miles.) 

 This is the first value, I believe, which any one has dared to as- 

 sign to a motion in which we all participate ; but in order to ob- 

 tain a value at all probable, there is required an astonishing degree 

 of perfection in the astronomical determinations. 



By comparing the particular motions presented by stars of dif- 

 ferent classes, with this motion of the solar system, the author 

 finds that the former, at the mean, are 2-4 times greater than that 

 °f the sun j whence it follows that this luminary may be ranked 



among those stars which have a comparatively slow motion in 

 space. 



Mr. O. Struve subjected the direction of the solar motion to a 

 ne w examination, and found that this motion is directed toward 

 a point in the heavens whose position, for the middle of the 

 ^ar 1792, was the following : R. A. 261° 23', Dec. 37° 36' N. 

 rgelander had found for these elements respectively : R. A. 

 457 SO', and Dec. N. 28° 50'. 



tie agreement in right ascensions in these two determinations 

 IS l ° Iera bly satisfactory, the difference being within the limits of 

 Probable errors. As to the values of declination which differ 

 °nsiderably, Struve thinks that it might result from small con- 

 errors in the differences of declination deduced from the 

 ^alogues of 1755 and 1830. These errors cause the stars \vhich 

 e a smaller proper motion to give a less northerly declination 

 those whose proper motion is greater, 

 foil Con:i ^ m ng these two systems of values, we arrive at the 

 nin ln ^' ^ ase( ^ u P° n the examination of seven hundred and 

 34o 6 %T V6n differe nt stars, viz. R. A. 259° 9'-4, and Dec. N. 

 d6 ''5, with the probable errors of 2° 57'-5, and 3° 24? -5 re- 



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