14. ; REPORT—1862. 
On some of the Characteristic Differences between the Configuration of the 
Surfaces of the Earth and Moon. By Professor Hunnissy, F.R.S, 
The author pointed out that the peculiarities observed on the surface of our 
gatellite should be ascribed to the sole action of volcanic forces, whereas those which 
we find on the earth result from a combination of volcanic and atmospherical 
agencies. In order more perfectly to study these contrasts, he called attention to 
the most characteristic feature of all lunar volcanos, namely the ring- or hoop-shaped 
crater, surrounded by circular, nearly concentric ridges. On the earth’s surface, 
volcanos deviated more or less from this type; and if the deviations are due to the 
differences between terrestrial and lunar superficial forces, it must follow that such 
differences will be most distinctly manifested in those cases where such terrestrial 
forces possess the highest degree of energy. He illustrated this proposition by re- 
ferring to the peculiar structure of the volcanos in the island of Java, where the 
action of tropical rains and hurricanes has been effective in producing the widest 
differences between the terrestrial volcanic summits and those observed on the 
moon’s surface. While the hooped structure of the latter cannot be traced among 
the views of Javanese volcanos which are presented in the comprehensive work 
published by Dr. J unghuhn, we frequently find diagrams of volcanic cones show- 
ing radiating ribs like those of a folded lamp-shade or an umbrella half closed, an 
appearance due to the very recular manner in which the tropical torrents scoop out 
the friable and scoriaceous summits of the craters. The contrast which arises by 
comparing some of these drawings with the best lunar diagrams and photographs 
may prove highly interesting to geologists as well as to selenographers. 
On aBrilliant Elliptic Ring in the Planetary Nebula, AR 20° 56',N.P.D.101° 56’. 
By Wurm Lassett, .RS.; in a Letter to Dr. Len, RS, 
9 Piazza Sliema, Malta, 26th Sept. 1862. 
My prar Sir,—In directing my large equatorial upon the well-known plane- 
tary nebula situated in AR 20" 56", N.P.D. 101° 56’ (1862), it has revealed so 
marvellous a conformation that I cannot forbear to send you a drawing of it, with 
some description of its appearance. With comparatively low powers, e. g. 231 and 
285, it appears at first sight as a vividly light-blue elliptic nebula, with a slight 
prolongation of the nebula, or a very faint star at or near the ends of the transverse 
axis. In this aspect the nebula resembles in form the planet Saturn when the ring 
is seen nearly edgewise. Attentively viewing it with higher powers, magnifying 
respectively 760, 1060 and 1480 times, and under the most favourable circumstances 
which have presented themselves, I have discovered within the nebula a brilliant 
elliptic ring, extremely well defined, and apparently having no connexion with the 
surrounding nebula; which indeed has the appearance of a gaseous or gauze-like 
envelope, scarcely interfering with the sharpness of the ring, and only diminishing 
somewhat its brightness. This nebulous envelope extends a little further from the 
ends of the conjugate than from the ends of the transverse axis; indeed it is but 
yery faintly prolonged, and only just traceable towards the preceding and fol- 
lowing stars. There is a star near its border northwards, in the projection of the 
conjugate axis. 
The breadth or thickness of the ring is, unlike that of Saturn, nearly uniform or equal 
in every part, so that its form most probably is either really elliptic, and seen by us 
in aline nearly perpendicular to its plane ; or if really circular and seen foreshortened, 
a section through any part of it limited by the internal and external diameters must 
be acircle. In other words;it will be like a circular cylinder bent round. It could 
scarcely fail to bring to my mind the annular nebula in Lyra, especially as there is 
a conspicuous central star (proportionally, however, much brighter than that which 
is in the centre of that nebula) ; and yet the resemblance is only rudely in form ; for 
this ring is much more symmetrical and more sharply defined, suggesting the idea 
of a solid galaxy of brilliant stars. 
The ring is not perfectly uniform in brightness, the south-preceding part being 
slightly the most vivid. ‘The transverse axis is inclined to the parallel of declina~ 
tion about 13°, A, series of micrometrical measures of the length and breadth of 
