Fan. 26, 1882 | 
NATURE 
295 
has been overflown by lava at various times, but especially 
by the eruptions of the last two years. Last June, arising 
from the plain or platform of lava formed by the filling of 
the crater, was the cone of eruption. This was situated 
east-north-east of the axis of the mountain. It formed a 
small steep-sided cone till the eruption of July destroyed 
the northern portion, forming a large low crater. Its 
condition on November 5, when I visited the crater or 
craters, was most instructive, and reminds one of a figure 
and description given by Sir W. Hamilton in his “ Campi 
Phlegrei.” 
Arriving at the edge of the 1872 crater from the west 
one crosses the crater plain, and arrives at a low semi- 
circular ridge with an average height of about twenty feet. 
Ascending this rim-like heap of scoria, one observes occu- 
pying its irregular bottom fumaroles and yellow patches 
of decomposing lava. The complete crater of July is 
formed of this ridge, together with the southern portion 
of the former cone of eruption. Within this space rose 
another cone of eruption whose centre was occupied by 
the main vent. On this occasion it was possible to ap- 
proach within a few yards of the great mouth, from which 
issued the column of vapour and momentary puffs of fluid 
lava fragments. Thus it will be seen that there are at 
present three cones and craters one within the other. 
This, however, was not the most interesting point. In 
the lava of the great plain we discovered a large cone or 
lava tunnel about eight feet high, twenty or thirty feet 
long, and fifteen feet broad, but with a general slope 
downwards. The roof was composed of lava about eight 
months old, but much decomposed. The whole cave 
presented one glistening forest of stalactites, some three 
hundred about were counted ; also stalagmites. Most of 
these were from two to three feet long, and a few twicc 
that length ; many, however, with a uniform diameter of 
less than an inch throughout and tubular, divided by 
septa, reminding one of an Crthoceras in structure. The 
colours most various and beautiful: bird’s-egg blue, acqua 
marine, salmon white, yellow, and reddish brown, and 
many variegated in these colours. The effect after the 
eyes quitting the rugged and fierce scenes around seemed 
to rest on some fairy cave. : 
On attempting to approach the entrance the gust of hot 
air, redundant with hydrochloric acid vapour, almost 
prevented one from making an attempt at an entrance. 
However, these beautiful and interesting prizes determined 
me to make an endeavour. Nose and mouth muffled, 
and having placed my friends on each side of the entrance 
with a strap, | made a dive down some steps. The effect 
was at first almost suffocation, stinging of the conjunctiva, 
and a profuse perspiration. To grab a few of those sta- 
lactites near at hand and return was the work of a minute, 
then the hearty pull-up by my friends, a fit of coughing 
and a little fresh air restored me. This was repeated 
eight times, during which I was able to obtain all the 
best specimens, some thirty examples, and reach the ex- 
tremity of the cavity. These prizes were carried carefully 
to Naples, where they have been placed under glass in a 
dry atmosphere, since they were highly deliquescent. A 
qualitative analysis gives the chief component as chloride 
of sodium, with chlorides of potassium, iron, manganese ; 
sulphates of soda, potash, iron, and copper. 
They were undoubtedly formed in the following man- 
ner :—The heavy rains we have had here lately dissolved 
out the materials from the decomposing lava above. The 
solution as it descended was evaporated by the current of 
hot air continually circulating through the cave, thus 
driving off the water and depositing the salt. Many 
showed within their cavities crystals of Halite Sylvine, 
and a few also Molysite. 
December.—In the early part of this month lava com- 
menced to flow down the eastern or Pompei side ; this, 
although not seen from Naples, gave a brilliant reflection 
at night which could be observed from the city. This 
aurora continued with variable intensity until December 
25, 1881, when it reached its climax. The lava had com- 
menced to issue by a fissure nearly north of the base of 
the cone of eruption. During the three weeks that it 
flowed this fissure had become widened and opened up. 
On Christmas and the following day the quantity of lava 
increased much in quantity, and altogether Vesuvius was 
much more active. The rent at this time had extended 
down the slope about one-third the distance of the Vesu- | 
vian cone and formed at its upper or wider part, an 
opening of about 120 feet in breadth by the same in depth. 
The floor which I visited and walked up on December 29 
was covered by the scoria and lava blocks continually 
falling from its edges. This floor sloped downwards to 
the end of the fissure at a small inclination. From its 
termination issued the larva already spoken of. 
This was a good example of the opening up of a dyke 
to the surface of a volcanic cone, so lucidly described by 
Mallet (“ Mechanism of Production of Volcanic Dykes, 
and on those of Mount Somma,” Quart. Journ. Geol. Soc. 
vol. xxxii. p. 472). 
The lava that issued at first descended the cone, crossed 
the Valle dell’ Inferno, following the course of the 1834 
stream, and threatening Otajano. It stopped, however, 
and followed a course across the Atrio in a north-east 
direction, where it can do no harm, 
An important fact was brought out by this eruption, 
small as it was. When the level of the lava in the vent 
had been lowered by exclusion of the fissure downwards 
an entire change of ejectamenta took place. The soft 
masses of pasty lava as ejected generally was replaced by 
rounded fragments of solid and old lava and volcanic 
ashes. The cone of eruption having no Jonger the column 
of lava to support it internally had crumbled in and was 
being ejected piecemeal by the explosions in the form of 
stones and ash. ‘This we had practical experience of. 
At one time approaching somewhat incautiously through 
the mist we were practically warned to beat a hasty 
retreat by hearing the rattle around us of small, and the 
heavy thud of larger stones. The beautiful yellow crater 
plane of 1872 had been covered by the dull grey ash, only 
relieved by numerous green-coloured saline crusts rich in 
copper. This was made evident on looking at our boot- 
soles, where we found the nails thickly plated with 
metallic copper. a 
Near the end of the above-mentioned fissure the lavas 
were flowing down the mountain in a tunnel. The roof 
had broken through at one place, and standing a few 
yards above this a fine sight presented itself. Figure a 
long fairly regular arched passage of about a metre and a 
half wide by the same in depth, along which one could 
see for one or two hundred yards. 
This was bright red-hot, and flowing along its floor 
with considerable rapidity was a stream of bright orange- 
coloured lava with the liquidity almost of water. In this 
we were able to carry on some experiments on the specific 
gravity of molten and cold lava, which reverse the results 
obtained on former occasions by Palmieri and others, and 
which will prove that cold is of higher specific gravity 
than molten rock, as theoretically should be the case. 
These facts, however, will be described elsewhere. 
H. J. JOHNSTON-LAVIS 
ILLUSTRATIONS OF NEW OR RARE ANIMALS 
IN THE ZOOLOGICAL SOCIETY’S LIVING 
COLLECTION * 7 
ne Aves Beatrix Antelope (Oryx Beatrix).—The ante- 
lopes of the genus Oryx constitute a well-defined 
and most beautiful group of the Bovine Family. Although 
not amongst the largest of the antelopes, they are animals 
of above the average size in the group. The males are 
t Ccntinued from vol. xxiv. p. 534- 
