558 
support of the column oflava within the chimney. This lower- 
ing of level probably produced the extension outwards of the 
eastern dyke, and the lateral outlet of lava was consequently 
lowered. This was confirmed by the much increased outflow of 
lava coincident with the falling in of the cone. 
During the first week in July the volcano appeared from 
Naples to be very quiet ; indeed, less vapour was escaping from 
the summit than at any time during the last seven years. From 
time to time the vapour was, from the gradually increasing pres- 
sure, able to burst its way through the loose materials that 
choked the outlet, when a puff of smoke would be visible of a 
dark purplish-black colour, due to its being charged with vol- 
canic ash derived from the churning up and trituration of the 
lava fragments, scoria, and lapilli it had to traverse in its escape. 
At the same timea slight reflection was to be seen at night, indi- 
‘cating that the lava surface, although lowered, was not so to any 
great extent. 
On this day, July 8, the lava which had always been gradually 
advancing, had crossed the southern end of the Val d’Inferno, 
and flowing down one of the wooded ravines on the property of 
the Prince of Ottajano, where it destroyed a number of trees, it 
continued its course, overwhelming some vine-gardens. | On 
July 12 the number and quantity of the black smoke puffs was 
very great, and the crater was in the full ash-forming stage, and 
towards night the vent had been considerably cleared, so that 
the reflection was well marked. The next day the smoke issued 
freely and uncharged with ash. The change that took place on 
the 12th was no doubt due to the lava rising in the chimney 
-consequent upon the lateral outlet getting choked ; as on the 11th, 
the abundant flow of lava became very much diminished. 
On July 20 the puffs of dark smoke again appeared, indi- 
cating a return of the crumbling in of the crater ; this was again 
due to the lowering of the lava level, and, as was expected, the 
fluid rock issued in great abundance the following day, again 
destroying trees and vine-gardens. The next day the lava 
was still flowing in abundance, so as to form a bright streak on 
the slope of the great cone. The outflow continued to gra- 
dually diminish until the 3oth, the crater above remaining 
inactive. On the latter date, however, the lava rose again 
sufficient within the chimney to cause the vapour to find a 
passage through the materials choking the main vent, so that 
on that day the puffs of black smoke were again abundant, and 
accompanied by the ejection of partially triturated subangular 
old lava and scoria fragments. In the evening bright bursts 
were well marked, showing that the vent was again cleaved. 
The two following days the volcano maintained the third degree 
of activity (Rep. Brit. Assoc., 1885, p. 395)- 
During the first week of August the lava again flowed rather 
freely from the mountain’s side, whilst from its summit hardly 
any vapour escaped except from time to time a puff of blaek 
smoke. On August 7 a visit was paid to the crater. The cone 
of eruption has been reduced in height about 30 metres, and its 
remnants form a low crater ring inclosing a crater of oblong 
form having a diameter of about 80 X 60 metres. Its greater 
axis lies in a line from about E.S.E. to W.N.W., and its bottom 
is double, so that it seems to result from two craters closely 
overlapping each other. The crumbling-in process was still 
going on, and the trituration of the loose stones and the charging 
of the vapour puff by the ash or sand could be watched from a 
distance of a few yards. I was successful in obtaining two 
ordinary and two instantaneous photos of the interior of the 
crater, only the eastern half of which, however, was active. 
The principal facts that may be gathered from the study of 
the phenomena of Vesuvius during these few months are rather 
confirmations of what the author has described as the mechanism 
of lateral eruptions, which may be summed upthus. The lower- 
ing of lava level within the chimney due to a lateral outlet 
removes the support the former gave to the walls of the crater 
and vent, which in consequence tumble in and choke more or 
less of the main outlet. Next the vapour contained in the lava 
may be compelled to escape laterally, but has a natural tendency 
not to do so, but rather to seek its path straight upwards. If 
the lateral outlet becomes choked, the lava immediately com- 
mences to rise in the chimney, and the escaping vapours burst 
through the loose materials in the chimney in puffs, grinding 
and triturating them, carrying upwards their dust, which tints 
the smoke of a dark colour, and, falling around the volcano, 
constitutes one of the forms of ‘‘volcanic ash,’ the chemical 
‘composition of which represents that of all the rocks triturated 
plus the saline substances condensed from the smoke. If one 
NATURE 
[Oct. 7, 188 
walks across this ash when damp, one may notice the immediate 
plating of their boot-nails with copper, showing the abundance 
of the chloride of that metal. H. J. JounsTon-LAvis 
THE ADELAIDE BOTANIC GARDEN AND 
GOVERNMENT PLANTATION 
HE report of Dr. Schomburgk on the progress and condition 
of the Botanic Garden and Government Plantation, Ade- 
laide, during the year 1885 has just reached us. Speaking first 
of the rainfall, Dr. Schomburgk says that the year was one of 
the driest and most ungenial that he ever had to contend with, 
the rainfall being no more than 15°887 inches, which was 2°851 
inches less than the fall of 1884, and 5:°272 below the average 
rainfall during the previous forty years. During September, 
October, November, December, and January no more than 3 
inches of rain fell, and the keat during these months was abnor- 
mally great. The drought and heat combined had an injurious 
effect upon the vegetation, especially upon many of the trees 
and shrubs in the Botanic Garden, natives of cooler countries ; 
the losses sustained, however, were not so great as was ex- 
pected, owing to an abundant supply of water. On the other 
hand, in May and June severe frosts were experienced, so that 
tropical and sub-tropical plants and shrubs suffered greatly. 
On the question of the introduction and acclimatisation of 
new economic plants, Dr. Schomburgk records his experience 
with many that have been widely distributed through the agency 
of the Royal Gardens, Kew, and have become known and esta- 
blished in other colonies as well as in India, such, for instance, 
as the Kumara (/fomea chrysorrhiza), the tubers of which form 
an article of food in New Zealand. Dr. Schomburgk says he 
believes that the plant will grow well in the gullies, because the 
climate there is cooler and moister than on the plains, and to some 
extent approaches that of New Zealand. The Gingelly oil plant 
(Sesamum indicum) is also reported upon favourably. The seeds — 
were sown in drills in the open ground in October, and came up 
in about fourteen days. Considering that neither the dry spring 
nor the summer heat affected the plants, there seems no doubt 
that the species can be successfully cultivated in South Australia. 
The plant is an annual, and is very largely grown in warm 
countries for the sake of the sweet limpid oil now so much used 
for mixing with olive oil. 
Under the head of XAofala sp. an* announcement is made of 
the receipt from Kew of a parcel of seeds of a tree belonging to 
the above-named genus, a native of Columbia, with the follow- — 
ing extract from a letter of Mr. W. T. Thiselton Dyer :—*‘ The 
Rhopala is a small contorted tree growing to about twenty feet 
in height. It is remarkable for being absolutely indestructible 
by fire, in large districts where the dry pastures and bush are 
burnt twice a year. Its resistance to fire enables it to exist to 
the exclusion of all other trees and bushes as a perfect natural 
plantation. The periodical burning destroys everything except 
this tree. The resemblance to a plantation is moreover en- 
hanced by the circumstance that the trees never form thickets, 
and they are thickly and almost systematically dispersed over the 
land. ‘The tree delights in the most sterile soils, but always of 
a stony or shingly character. Sometimes it grows in places 
so barren that even grass cannot exist. “This suggests the 
idea that it may be turned to account in sterile districts within 
the tropics.” “Dr. Schomburgk expresses some doubt whether 
the plant will thrive out of doors with them, but thinks it may 
do well in the Northern Territory. 
The Herbarium and Museum have both been considerably 
enriched by additional specimens during the year, so that the 
utility and efficiency of the whole establishment are thoroughly 
maintained, 
THE AMERICAN ASSOCIATION 
fp ROM the report in Scéence of the Buffalo meeting of the 
American Association we condense the following brief 
summary :— 
Prof. Gibbs’s maslerly address, in the Section of Mathematics 
and Astronomy, upon the subject of ‘‘ Multiple Algebra,” was 
too long and of too technical a nature for presentation in full to 
our readers. His opening remarks were as follows:— 
“Tt has been said that ‘the human mind has never invented 
a labour-saving machine equal to algebra.’ If this be true, it is 
but natural and proper that an age like our own, characterised 
