148 
SECOND REPORT - 1832 . 
stars that have yet been obtained. In the Monatlicke Corres¬ 
pondent , vol. 26, Bessel had speculated on the relative motion 
of the stars of 61 Cygni; and in the Phil. Trans. 1824, maps of 
the apparent relative motions of 61 Cygni and £ Bootis were 
given. In many cases it is doubtful whether the apparent mo¬ 
tion may not be produced by the motion of our system (sup¬ 
posing the stars unconnected and at very different distances), 
and whether a part of it may not depend on annual parallax. 
But in this paper it is shown that £ Cancri and £ Ursae Majoris 
have nearly completed an entire revolution since they were first 
observed; that y Coronae has probably made more than a re¬ 
volution ; and that Castor, y Virginis, cr Coronae, TO Ophiuchi, 
61 Cygni, and others, are undoubtedly connected as binary sy¬ 
stems, and have changed their position remarkably.—Other pri¬ 
vate observers, I believe, in this country, are employed on the 
measures of these objects. 
The belief in the connexion of double stars by some law of 
attraction naturally excited a desire of reducing their orbits to 
calculation. Every attempt that has been made has assumed 
the law to be that of gravitation. In the Conn, des Temps 
1830, Savary gave a method requiring four complete observa¬ 
tions of distance and position, which he applied to determine 
the relative orbit of the two stars of £ Ursae Majoris. (In the 
history of methods it is remarkable that one of the distances 
actually used by him for £ Ursae Majoris was concluded from 
the others by the ratio of the angular motions.) In the Berliner 
Jahrbuch 1832, Encke gave a method, also requiring four com¬ 
plete observations, which he applied to 70 Ophiuchi. But Sir 
John Herschel has lately communicated to the Astronomical 
Society a method which, for elegance and practical utility, must 
I think be placed above every other that has appeared. For 
reasons of which only an observer can judge, he rejects entirely 
the measures of distances; and from the observed angles of 
position only (of which any number can be used, and the more 
the better,) he obtains, by a singularly skilful mixture of graphi¬ 
cal construction and numerical calculation, all the elements of 
the orbit. This method has been applied to y Virginis, <r Co¬ 
ronae, Castor, 70 Ophiuchi, and £ Ursae Majoris; and an ephe- 
meris of the first (whose position will change very rapidly in 
the next few years,) is now published in the Supplement to the 
Nautical Almanac. This is really a new step in science. 
A very extensive series of observations of nebulae, it is under¬ 
stood, is nearly completed by Sir John Herschel; but nothing 
has yet been published. 
Among the changes in nebulae that have been suspected, one 
