52-'^ BIBLIOGRAPHY OF HERSCHEL's WRITINGS. 



Hersehel, V/.: Synopsis of the Writings of — Continued. 

 AD. Yol. P. 



1782 72 143 t Boolis : "I suspect a motion in ono of the stars, Avliich another year 

 or two may show." 



143 V Draconis : ' ' From the x)ositiou in Flamsteed's catalogue " we gather 

 that in his time their distance was * * * *, The difference iu 

 the distance of tlie stars is so considerable that we can hardly ac- 

 count for it otherwise than by admitting a proper motion in one or 

 both of the stars or in our solar system ; most probably neither of 

 the three is at rest." 



147 a Lyme: I have often measured the diameters of the fixed stars, and 

 found they measui-ed less and less the more I magnified. With a 

 power of G450 I looked at this star for at least a quarter of an hour, 

 * * * having experimentally found that the aberration by this 

 means will appear less and less, a Lyrce was perfectly round ; its 

 diameter was 0".3553. 



150 Sixth Class of Double Stars [66 stars]. 



150 o Cell : " I can hardly doubt the motion of this star." 



157 Postscript to the Catalogue of Double Stars. 



Since delivering the paper on the Parallax of the Fixed Stars [P7n7. 

 Trans., 1782], in which I refer to the above Catalogue of Double Stars, 

 I have received a paper of Mr. Mayer's ' 'De novis i n Coelo sidereo phaj- 

 nomenis" wherein I see that the idea of ascertaining the proper mo- 

 tion of the stars by means of small stars near large ones has induced 

 that gentleman before me to look out for such small stars. My view 

 being that the annual parallax required stars much nearer than 



158 those that would do for Mr. May'er's purpose, therefore I exam- 

 ined the heavens with much higher powers, and looked out chiefly 

 for those that were exceedingly close. The above catalogue con- 

 tains 269 double stars, 227 of which, to my present knowledge, have 

 not been noticed by any j)erson. I hope they will prove no incon- 

 siderable addition to the general stock, especially as there are a 

 great many which are out of the reach of Mr. Mayer's and other 

 mural quadrants or transit instruments. 



158 A power of 70 or SO was not enough for the stars of Class I nor even 

 those of Class II. 



158 In settling the relative situation of very close double stars neither Mr. 



May'er's instrument nor his method were adequate to the purpose. 



159 Comparison of the measures of Mayer and Herschel on a Gevii- 



norum : 

 "Mr. Mayer: Distance, 9". 635 from center to center; position, 23° 

 14' n. preceding ; magnitude, extremely unequal. Mine : Distance, 

 5". 156, diameter included; position, 32° 47' n. preceding; magni- 

 tudes, a little unequal." [See Fig. 6, Plate IV, for a cut of the ap- 

 jiearance of this star with power of 460.] 



160 I do not mean to depreciate Mr. Mayer's method ; with stars of Classes 



IV, V, VI, and some of Class III, better can hardly be wished for ; 

 it is not sufficient for stars of Class II, much less for those of Class I. 



161 I have used the expression "double star " in a few instances of Class VI 



in rather an extended signification. I preferred that expression to 

 any other such as comes, companion or satellite, because, in my 

 opinion, it is much too soon to form any theories of small stars re- 

 volving round large ones. 



162 I shall not fail to take the first opportunity for looking out for those 



of Mr. Mayer's double stars which I have not in my catalogue, 

 amounting to 31, and also for [another in Connaissauce des Terns]. 



