254 



result, but also the difference between the greatest and least mean? 

 taken, or the limits within which all the measures necessarily lie. 



The stars themselves are arranged in order of right ascension for 

 convenience of reference. After the statement of the mean results 

 of the several sets of observations both of angle and distance, a final 

 mean with a mean date for an epoch is deduced. In the case of Sir 

 William Herschel's stars, a comparison of the measures now obtained 

 with those given in his catalogues, or now for the first time brought 

 to light by a careful examination of his manuscripts, is subjoined. 

 By this comparison several fresh instances have been found of double 

 stars, in which the relative motion of the individuals composing them 

 is satisfactorily proved. In one remarkable case (that of the star 

 $ Equulei,) this change has gone to an enormous extent, and is sa- 

 tisfactorily referred to proper motion in the large star. In another 

 not less singular, all the three stars of a triple star ( Cancri) are 

 ascertained to be relatively in motion, describing orbits about each 

 other, and forming probably a ternary system by the mutual gravita- 

 tion of its members, thus completely justifying the views taken by 

 Sir William Herschel of this subject, in his papers published in the 

 Transactions of this Society in 1802 and 1804. 



Annexed, as an appendix to these observations, is a re-examination 

 of about 27 stars measured in the former paper already alluded to, 

 and which were considered as presenting peculiar interest, from the 

 evidence then obtained of their relative motion and of their connexion 

 in binary systems. The results of this re-examination are in the 

 highest degree satisfactory, as, with only two or three exceptions, 

 these stars have been found to continue their motions in the direc- 

 tions, and in the greater number of cases with nearly the velocities, 

 predicted. In the most remarkable case, that of the double star 

 Ursse Majoris, an angle of nearly 14 has thus been described by the 

 two stars about their common centre of gravity in an interval of less 

 than two years, thus affording every probability that in a very few 

 years we shall arrive at a perfect knowledge of the figure, elements, 

 and position of their orbits, and be enabled by strict calculation to 

 answer the important question, whether the Newtonian law of at- 

 traction is confined to our own system or obtains also in the sidereal 

 heavens. 



An Account of the Construction and Adjustment of the New Standards 

 of Weights and Measures of the United Kingdom of Great Britain 

 and Ireland. By Captain Henry Kater, F.R.S. Read November 

 24, 1825. [Phil. Trans. 1826, Part II. p. 1.] 



The author, after stating that the weights and measures of the 

 United Kingdom are founded on a standard whose length is deter- 

 mined by its proportion to that of a pendulum vibrating mean time 

 in London, which has been ascertained by him to be 39' 13929 inches 

 of Sir George Shuckburgh's scale, considers it necessary, on account 

 of the importance of the result, to consider what degree of confidence 



