440 
ME. W. HUGGINS ON THE SPECTRA OE SOME OP THE NEBULAL 
spectrum was suspected. This nebula contains probably a very small quantity of matter 
condensed into the liquid or solid state. 
The colour of the light of this nebula is greenish blue. 
Lord Rosse has not detected any central star, nor any perforation, as seen in some 
of the other planetary nebulse. He represents it with ansae, which probably indicate a 
nebulous ring seen edgeways*. 
[No. 4447. 2023 h. 57 M. R.A. 18 h 48 m 20 s . N.P.D. 57° S' 57"-2. An annular 
nebula; bright; pretty large; considerably elongated.] In Lyra f. 
The apparent brightness of this nebula, as seen in the telescope, is probably due to 
its large extent, for the faintness of its spectrum indicates that it has a smaller intrinsic 
brightness than the nebulae already examined. The brightest of the three lines was 
well seen. I suspected also the presence of the next in brightness. No indication what- 
ever of a faint spectrum. The bright line looks remarkable, since it consists of two 
bright dots corresponding to sections of the ring, and between these there was not dark- 
ness, but an excessively faint line joining them. This observation makes it probable 
that the faint nebulous matter occupying the central portion is similar in constitution to 
that of the ring. The bright line was compared with the induction-spark J. 
[No. 4964. 2241 h. 18 H. IV. R.A. 23 h 19 m 9 s -9. N.P.D. 48° 13' 57"*5. Planetary ; 
very bright; pretty small, round, blue.] 
With a power of 600 this nebula appears distinctly annular. The colour of its light 
is greenish blue§. The spectrum formed by the light from this nebula corresponds with 
that of 37 H. IV. represented in fig. 5, Plate X. 
* Philosophical Transactions, 1850, p. 507 and Plate XXXYIII. fig. 14. 
f Lord Rosse, in his description of this nebula, remarks, “ The filaments proceeding from the edge become 
more conspicuous under increasing magnifying power within certain limits, which is strikingly characteristic of 
a cluster ; still I do not feel confident that it is resolvable.”- — Philosophical Transactions, 1844, p. 322 and 
Plate XIX. fig. 29. 
In 1850 Lord Rosse further remarks, “ I have not yet sketched it with the 6-feet instrument, because I 
have never seen it under favourable circumstances : the opportunities of observing it well on the meridian, are 
comparatively rare, owing to twilight. It was observed seven times in 1848, and once in 1849. The only addi- 
tional particulars I collect from the observations are that the central opening has considerably more nebulosity, 
and there is one pretty bright star in it, s. f. the centre, and a few other very minute stars. In the sky round 
the nebula and near it there are several very small stars which were, not before seen; and therefore the stars 
in the dark opening may possibly be merely accidental. In the annulus, especially ,at the extremities of the 
minor axis, there are several minute stars, but there was still much nebulosity not seen as distinct stars.” — 
Philosophical Transactions, 1850, p. 506. 
' “Nothing additional since 1844, except a star s. f. the middle.” — Philosophical Transactions, 1861, p. 732. 
• t Already in 1850 Lord Rosse had discovered a connexion in general plan of structure between some of the 
nebulse which present small planetary disks in ordinary telescopes, and the annular nebula in Lyra. His words 
are, “There were but two annular nebulse known in the northern hemisphere when Sir Johx Heksohel’s 
Catalogue was published ; now there are seven, as we have found that five of the planetary nebulse are really 
annular. Of these objects, the annular nebula in Lyra is the one in which the form is the most easily recog- 
nized.” — Philosophical Transactions, 1850, p. 506. 
§ Eor Lord Rosse’s observations of this nebula, see Philosophical Transactions, 1844, p. 323; ibid.. 1850, 
p. 507 and "Plate XXXYIII. fig. 13 ; ibid. 1861, p. 736 and Plate XXX. fig. 40. 
