5oo 
Dr. Herschel's Catalogue 
he be convinced now, when changes in its shape and lustre have 
been seen, that its light is not, like that of the milky-way, com- 
posed of stars. To attempt even a guess at what this light may 
be, would be presumptuous. If it should be surmised, for in- 
stance, that this nebulosity is of the nature of the zodiacal 
light, we should then be obliged to admit the existence of an 
effect without its cause. An idea of its phosphorical condition, is 
not more philosophical, unless we could shew from what source 
of phosphorical matter, such immeasurable tracts of luminous 
phenomena could draw their existence, and permanency ; for, 
though minute changes have been observed, yet a general re- 
semblance, allowing for the difference of telescopes, is still to be 
perceived in the great nebulosity of Orion, even since the time 
of its first discovery. 
X. Of nebulous Stars . 
The nature of these remarkable objects is enveloped in much 
obscurity. It will probably require ages of observations, before 
we can be enabled to form a proper estimate of their condition. 
That stars should have visible atmospheres, of such an extent 
as those of which I have given the situation in this and my 
former catalogues, is truly surprising, unless we attribute to 
such atmospheres, the quality of self-luminous milky nebulosity. 
We can have no reason to doubt of the starry nature of the 
central point; for, in no respect whatever does its appearance 
differ from that of a star of an equal magnitude ; but, when the 
great distance of such stars is taken into consideration, the real 
extent of the surrounding nebulosity is truly wonderful. A very 
curious one of this kind will be found in the 4 th class, No. 6g , 
of the annexed catalogue. 
