92 STATEMENT AND EXPOSITION OP 



published in 1852; and among tliose expositions is one, drawn out in detail, the 

 heading of which is "-The MUlcy Way — a Spiral " which is found in No. 37 of 

 the Journal specified, at p. 101; followed by some reasons for supposing that the" 

 spiral had four branches, and a dense central cluster.^ 



For a variety of other details as well as a more complete exposition of the 

 phenomena and their progress, reference must be made to the memoir itself; but 

 one of its concluding paragraphs should, if possible, be made emphatic ; and, there- 

 fore, we also introduce it here. It reads thus: — ■ 



" While it is even to be expected that errors may hereafter be found in the 

 various details which have been so fully exhibited, it is respectfully submitted 

 whether this same hypothesis of the spheroidal origin of so many of the clusters 

 and nebulae, in its most important features, is not adequate in mode ; or whether, 

 in the very least, the phenomena do not even require the admission of a dynamical 

 equilibrium destroyed, as the one pervading principle — guiding, as it would also 

 seem, to the explanation of all the other conditions." 



It would seem, indeed, to be in vain to look for an exposition of the phenomena 

 and their progress, if we do not keep in view and adhere to the hypothesis of a 

 dynamical ec[uilibrium destroyed ; a conservative view does not now suit the case. 



Among the conditions requiring just that, are the phenomena here briefly ad- 

 verted to ; and the fact that the centres of clusters do not exhibit the enormous 

 condensation anywhere, which the "clustering power" of Sir William Herschel, 

 it would seem, must somewhere have produced ; but, on the contrary, the central 

 portions uniformly appear as if, Avhen they were released from superincumbent 

 pressure, by the rupture of the outer portions of the spheroid, or other primitive 

 form, their feeble central attraction could no longer preserve them in form ; and so 

 the centres are always broken up. The sudden Gurvatu,re of the spirals, moreover, 

 seems to be more like that due to the ejection of material under the influence of 

 an excess of centrifugal force, than that which would result from a rushing inward, 

 in obedience to an excess of attraction. 



The supposition of orignial nehidous spheroids does not seem to be contradicted 

 by the revelations of the spectroscojje j but, on the contrary, to be consistent with 

 them. 



In further justification of an hypothesis, the distinguishing feature of which is 

 the utter destruction, on the large scale, of a dynamical equilibrium, we also re- 

 produce the conclusion of the communication already referred to, which is as fol- 

 lows : — 



The more condensed clusters (other things being equal) must, upon this plan, 

 be regarded as probably of the more recent origin; instead of being the older, as 

 supposed by Sir William Herschel (Phil. Trans, for 1789, pp. 224 and 225); and 

 if a continued dispersion is even yet in progress, the permitted collisions regarded 



■■ This assuredly must have been overlooked, or else — though noticed — have been forgotten; or 

 we would mi find among the Proceedings of the Royal Agronomical Societi/ (Dec. ISfifl), "A. New 

 Theory of the Milky Way, by R. A Proctor, B. A. ;" which describes and figures the Milky Way as 

 being a apiral — Ihough not, indeed, with four branches. 



