BIBLIOGRAPHY OF HERSCHEL's WRITINGS. 009 



Herschel, W.: Synopsis of the Writings of— Continuctl. 



4. V. Vol. p. 



We shall be able to say that a distant celestial object is so far from 

 lis, provided the stars of which it is composed are, of a size and 

 lustre equal to the size and histrc of such stars as Sirius, Arctnrus, 

 etc. 

 1817 107 3)J1 The stars of the tenth, eleventh, and twelfth order of distances are 

 not only more compressed than those in the neighborhood of the 

 sun, but, moreover, their compression in different parts of the 

 heavens must be very unequal. 

 IX. Of the construction and extent of the milky wai/. 

 322 General description of it. 



The sun is within its plane, for to an observer in latitude 60°, when 

 at 100° R. A. the milky way is in the east, it will at the same time 

 be in the west at 280° ; while in its meridional situation it will pass 

 through Cassiopeia in the Zenith and through the constellation of 

 the Cross in the Nadir. 

 323-4 Examination of the cluster in the Sword Handle of Perseus, with 

 various space-penetrating powers. 



325 [Beside the 8G3 gauges published in Phil. Trans., 1785, p. 221, above 



400 more have been taken in various parts of the heavens and are 

 not published.] 



326 The twenty-foot telescope cannot fathom the profundity of the milky 



way. 



326 If the stars of the 5th, 6th, and 7th magnitudes cannot bo supposed 



to be gradually of a smaller physical size and brightness than those 

 of the^lst, 2d, and 3d, how much less can a supposition be admitted 



■ that would require that the stars which, by a long series of ganging 

 powers, have been proved to make their gradual telescopic appear- 

 ance should also be gradually of a different construction with re- 

 gard to physical size and brightness from those which we see with 



the naked eye? . , , , , ^u 



327 The telescopic breadth of the milky way considerably exceeds the 



extent which, in our maps, is assigned to it. 

 328-30 Observations— sweeps— which confirm this. 

 330 X. Concluding Bemarks. 



What has been said of the extent and condition of the milky way m 



mv papers on the construction of the heavens, with the addition of 



■ this attempt to give a more correct idea of its profnndity.in space 

 will contain nearly all the general knowledge we can ever have of 

 this magnificent collection of stars. 



Our sun with all the stars we can see with the eye are deeply im- 

 mersed in the milkv way, and form a component part of it. 

 meibCLL . William Herschel. 



[ Dated] Slough, near Windsor, May 10, 1817. 



Astronomical ohservations and experiments, selccied for the purpose of as- 

 'certaininq the relaiwe distances of clusters of stars, and of investigating 

 how far the poicer of our telescopes may le expected to reach tn to space 

 'l/lv.cJ to a^liguous celesHal oljects. By «- William Hek- 

 ^rHEL Knt. Guelp., LL. D., F. R. S. Read Juno 11, 1818. 



The method of equalization of star light will show the relative dis- 

 tances of stars ; from this a method was explained in Phil T,-ans., 

 1817 by which means the profundity in space of every object con- 

 sisting of stars can be ascertained as f^ir as the light of the telescope 

 S. Mis.. 31 39 



331 



1818 108 429 



429 



