1872.] The Construction of the Heavens. 321 
admitted that we should attach especial value to the an- 
nouncements he then made. Yet the striking words with 
which he prefaces the paper of 1811 seem almost to have 
escaped notice :—‘‘I must freely confess,” he says, ‘that 
by continuing my sweeps of the heavens my opinion of the 
arrangement of the stars and their magnitudes, and of some 
other particulars, has undergone a gradual change; and, 
indeed, when the novelty of the subject is considered, we 
cannot be surprised that many things formerly taken for 
granted should, on examination, prove to be different from 
what they were generally but incautiously supposed to be. 
For instance, an equal scattering of the stars may be 
admitted in certain calculations; but when we examine the 
Milky Way, or the closely compressed clusters of stars, of 
which my catalogues have recorded so many instances, this 
supposed equality of scattering must be given up. We may 
also have surmised nebule to be no other than clusters of 
stars disguised by their very great distance; but a longer 
experience and a better acquaintance with the nature of 
nebulz will not allow a general admission of such a prin- 
ciple, although undoubtedly a cluster of stars may assume a 
nebulous appearance when it is too remote for us to discern 
the stars of which it is composed.” 
In the paper of 1811, however, Herschel does not (save in 
these prefatory remarks) consider the structure of the 
sidereal heavens. The paper is devoted exclusively to the 
discussion of the nebular hypothesis as to the formation of 
stars. It was not until 1814 that he endeavoured to extend 
his reasoning so as to include the subject of stellar 
grouping. ‘‘ The observations contained in this paper,” he 
says in 1814, ‘‘are intended to display the sidereal part of 
the heavens, and also to show the intimate connection 
between the two opposite extremes, one of which is the 
immensity of the widely diffused and seemingly chaotic 
nebulous matter; and the other, the highly complicated 
and most artificially constructed globular clusters of com- 
pressed stars.” In this paper he enters also into a discus- 
sion of ambiguous objects,—that is, objects ‘‘ of such a con- 
struction or at such a distance from us, that the highest 
power of penetration which hitherto has been applied to 
them, leaves it undecided whether they belong to the 
class of nebulze or stars.” 
But the chief interest of the paper of 1814 resides (in 
my judgment) in the remarks which Herschel makes 
respecting the clustering condition of parts of the heavens. 
He explains that his expression ‘‘ forming clusters,’ was 
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