84 COSMOS 



appear constantly to vary, sometimes appearing separated into 

 round or elliptical disks, single or in pairs, occasionally con- 

 nected by a thread of light ; whiles at another time, these 

 nebulae occur in forms of larger dimensions, and are either 

 elongated, or variously branched, or fan-shaped, or appear like 

 well-defined rings, inclosing a dark interior. It is conjectured 

 that these bodies are undergoing variously developed formative 

 processes, as the cosmical vapor becomes condensed in con- 

 formity with the laws of attraction, either round one or more 

 of the nuclei. Between two and three thousand of such un- 

 resolvable nebulae, in which the most powerful telescopes have 

 hitherto been unable to distinguish the presence of stars, have 

 been counted, and their positions determined. 



The genetic evolution — that perpetual state of development 

 which seems to affect this portion of the regions of space — 

 has led philosophical observers to the discovery of the analogy 

 existing among organic phenomena. As in our forests we sec 

 the same kind of tree in all the various stages of its growth, 

 and are thus enabled to form an idea of progressive, vital de- 

 velopment, so do we also, in the great garden of the universe, 

 recognize the most different phases of sidereal formation. The 

 process of condensation, which formed a part of the doctrines 

 of Anaximenes and of the Ionian School, appears to be going 

 on before our eyes. This subject of investigation and conject- 

 ure is especially attractive to the imagination, for in the study 

 of the animated circles of nature, and of the action of all the 

 moving forces of the universe, the charm that exercises the 

 most powerful influence on the mind is derived less from a 

 knowledge of that which is than from a perception of that 

 whiish tvill be, even though the latter be nothing more than 

 a new condition of a known material existence ; for ef actual 

 creation, of origin, the beginning of existence from non-exist- 

 ence, we have no experience, and can therefore form no con- 

 ception. 



A comparison of the various causes influencing the develop- 

 ment manifested by the greater or less degree of condensation 

 in the interior of nebulae, no less tharl a successive course of 

 direct observations, have led to the belief that changes of form 

 have been recognized first in Andromeda, next in the constel- 

 lation Argo, and in the isolated filamentous portion of the 

 nebula in Orion. But want of uniformity in the power of the 

 instruments employed, different conditions of our atmosphere, 

 and other optical relations, render a part of the results invalid 

 as historical evidence. 



