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Dr. Herschel has delineated the meeting of the arches, arising 

 from a calculation of the proper motions of the 36 stars in Dr. Mas- 

 kelyne's Catalogue, on a celestial globe ; and finds that, in the 

 northern hemisphere, no less than ten of those intersections are made 

 by stars of the first magnitude, in a very limited part of the heavens, 

 about the constellation of Hercules. Upon all the remaining surface 

 there is not the least appearance of any other than a promiscuous 

 situation of intersections, and only one of these made by arches of 

 principal stars. 



A table is then given of the calculated situations of the above- 

 mentioned ten intersections in right ascension and north polar di- 

 stance ; and it is observed, that if the intersections made by the 

 proper motions of some large stars of the next order, and the arches 

 in which the stars of the first magnitude move, are examined, no 

 less than fifteen unite with the former ten in pointing out the same 

 part of the heavens as a parallactic centre. This, Dr. Herschel 

 thinks, can hardly fail to be considered as a convincing proof of the 

 motion here treated of. 



The changes in the position of double stars are next considered ; 

 and these, Dr. Herschel thinks, it will be more eligible to ascribe to 

 the effect of parallax than to admit so many separate motions in the 

 different stars, especially as the parallactic motions of at least half 

 of the 56 double stars described by him, point out the same apex of 

 a solar motion by their direction to its opposite parallactic centre. 



Dr. Herschel then remarks, that if the proper motions of the stars 

 were such as they appear to be, they would exhibit an incongruous 

 mixture of great velocity and extreme slowness. Of this incongruity, 

 several instances are enumerated ; but it will, he says, be shown, 

 when the direction and velocity of the solar motion are explained, 

 that these incongruities are mere parallactic appearances. 



With respect to the occultation of a small star by a large one, 

 Dr. Herschel will, he says, prove, when the solar motion is esta- 

 blished, that the vanishing of the small star near $ Cygni is, as far 

 as we can judge at present, only a parallactic appearance. 



Dr. Herschel now proceeds to consider the direction of the solar 

 motion ; the expedience of admitting such motion being, he thinks, 

 after what has been said, no longer questionable. 



He begins by proving, that when the proper motions of two stars 

 are given, an apex may be found, to which, if the sun be supposed 

 to move with a certain velocity, the two given motions may be re- 

 solved into apparent changes, arising from sidereal parallax ; the 

 stars remaining perfectly at rest. The mode of proving this, in 

 which Arcturus and Sirius are used as examples, will not admit of 

 abridgement. But, from the nature of proper motions, it follows, 

 that when a third star does not lead us to the same apex as the 

 other two, its apparent motion cannot be resolved by the effect of 

 parallax alone : and, although we may account for the proper motion 

 of the third star, Capella for instance, by retaining the same apex of 

 the solar motion which explained the apparent motions of the other 



