BIBLIOGRAPHY- OF HERSCnEL's WRITINGS. 603 



Herschel, W.: Synopsis of the Wiutixgs of— Coutiniicil. 



A.D. Vol. P. 



1814 104 2(51 Class 2. Twonty-six objects of round or nearly round fij^uro. Tho 

 round figure of these show them to be globular. They nuist either 

 be in a condensed state jiurely nebulous, or else, if consisting of 

 stars, they nii^st be in an advanced order of compression, and only 

 appear nebulous on account of their very great distance from us. 

 A middle state between the progressive condensation of a globular 

 nebula and a cluster of stars can have no existence, because a glob- 

 ular nebulosity when condensed can only produce a single star. A 

 globular cluster may, however, intercept a uuiss of nebulous matter 

 in motion, in which case the nebulosity must soon assume the form 

 of the cluster, and will finally be absorbed by it. 

 Class 3. Twenty-six easily resolvable objects. 

 S62 Class 4. Twelve objects, probably clusters. 

 IX. Of the sidereal part of the Heavens. 

 Intimate connection between the nebulous and sidereal condition. 



263 Stars of first magnitude. [See Phil. Trans., 1785, p. G8.] 



264 Prismatic analysis of the light of Sirim, a Orionis, Procyon, Arciurus 



Aldcbaran and a Lyra:. 



265 X. Of the aggregation of stars. 



Star-gauges ijrove that the stars arc not equally distributed over the 



celestial regions. [See P/ii/. Trans., 1785.] 

 Forming clusters. This tendency to clustering is chielly visible in 



places extremely rich in stars. Its greatest effects will then be in 



and near the milky way. 



266 The twenty objects referred to are not given as instances of the actual 



formation of clusters, but merely to draw attention to a seemingly 

 aggregating arrangement. Fifteen of these are in the milky way 

 and five are near it. 



266 XI. Of irregular clusters. 



Clusters in very rich parts of tho heavens arc generally of irregular 

 form and imperfectly collected. One hundred and twelve such ob- 



267 jects are referred to ; eighty of size not noted, fifty-three of these in 

 the milky way, eighteen near it, nine at a distance from it. Also 

 thirty-two irregular clusters from 2' to 30' in diameter ; of these 

 twenty-two are in the milky way and ten near it. 



267 The great number of clusters in these two collections is not only an 



indication that they owe their origin to a clustering power residing 

 in the centre ; but the still remaining irregularity of their arrange- 

 ment additionally proves that the action of the clustering power 

 lias not been exerted long enough to produce a more artificial con- 

 struction. 



268 XII. Of clusters variously extended and compressed. 



Fifteen extended clusters named; twelve in the milky way, three 

 near it. Their descriptions show that the power which has drawn 

 tho stars together has acted under difierent circumstances in tho 

 several cases. 



269 XIII. Of clusters of stars of a peculiar description. 



Six sucli objects named: one in tho milky way, three near it, two at 

 a distance from it. 

 271 XIV. Of differently compressed clusters of stars. 



I have hitherto only considered the arrangement of stars in clusters 

 with a view to point out whether they are drawn together by a 

 clustering power in the same manner as tho nebulous matter has 



