THE EARL OF ROSSE’S OBSERVATIONS ON SOME OF THE NEBULA3. 
323 
think that it was never examined when the instrument was in as good order, and the 
night as favourable, as on the several occasions when the resolvable character of 
fig. 26 was ascertained. 
Fig. 47 is one apparently of another class. It has a star in the centre, and is of 
unequal brightness; the nebulosity is in patches, and I have sometimes fancied, 
though probably erroneously, that I could discover in it a faint resemblance to fig. 
26. The star in the centre is easily seen, and there is nothing peculiar in its appear- 
ance ; it is exactly like other stars seen in nebulae ; still it may really be but the bril- 
liant condensed centre of a very remote cluster. I have not, however, detected any 
gradual increase of brilliancy towards the centre. 
Not to multiply sketches which soon may require correction, I shall merely add 
that in fig. 32 we also find a star in the centre, and in fig. 85 likewise a star in the 
centre, and many other minute stars in and close to it, so that it is really a cluster. 
The double nebula (fig. 72) consists of two clusters, between which there is a star 
easily seen on even an indifferent night. In fig. 49 there are minute stars between 
and about the three large stars, and I think there can be no doubt it is a cluster. Fig. 
25 abounds in stars mixed with nebulosity ; I have not seen it on a very fine night, 
but it was observed by my assistant, and by a gentleman who was with him, and 
they had no doubt but that the centre was completely resolved. In the little annu- 
lar nebula, fig. 48, I see nothing remarkable, farther than a star in the north pre- 
ceding edge ; it is tolerably conspicuous, and is about half-way between the exterior 
and interior circumference of the annulus. 
Fig. 45 is a very remarkable object. It is no longer a planetary nebula, but an 
annular nebula, like that of Lyra, with a similarly fringed edge, though much less 
distinctly seen: it is oval, but the central portion is not so dark as that of Lyra ; it 
very closely resembles the annular nebula of Lyra seen with an instrument of infe- 
rior power. 
In several of the other figured nebulae something has been discovered as to matters 
of detail. In some we have found perhaps a few minute and apparently accidental 
stars, in others a larger extent of nebulosity, and consequently a different form of 
outline, but nothing of sufficient importance to make it desirable further to prolong 
this paper. It appears to me, however, to be an important fact, that all we have seen 
strongly confirms the accuracy of Sir John Herschels judgement in selecting the 
nebulae which he places in the class designated as resolvable. It is important from 
its bearing on future researches ; for where the power of our instruments is insufficient 
to do more than to bring to light distinctly the peculiar characteristics of resolvabi- 
lity, these once observed with due caution and their reality ascertained beyond doubt, 
we shall conclude with little danger of error, that the object is really a cluster. We 
should err, however, were we to assume the converse of the proposition, that the 
absence of all symptoms of resolvability was evidence conclusive that the object was 
not a cluster. In some instances, with increasing optical power, the resolvable 
