NATURE 
| dugust 5, 1886 
purifies the air. But when the rain first commences to 
fall, the number of bacteria increases. This Dr. Miquel 
explains by supposing that many of the first drops of rain 
evaporate—the atmosphere not being saturated with 
vapour—and deliver up the bacteria they hold to the air 
in the neighbourhood of the earth. Later on the air is 
saturated with vapour, and the bacteria floating in it are 
carried down to the ground in the drops of rain, and by 
this means the air is purified. 
Investigation of the organisms contained in rain show 
that the rain which first falls in a shower and that which 
falls after a period of dry-weather contain far larger 
numbers of bacteria than that which falls at any other 
times. Under such circumstances 200,000 microbes per 
litre is not an unusual quantity. The rain which falls 
during the warm months of the year—in summer and 
autumn—contains more microbes than that which falls in 
winter and spring. During the year 1883-84 the lowest 
monthly average was 1000 per litre in November, and the 
highest 6980 per litre in September. As the rain derives 
its organisins from the air which it purifies in its descent, 
we should expect the seasonal variations in the number 
of contained organisms in air and rain to correspond 
closely—as in fact they do. It is important to note that 
the organisms exist in the rain to a larger extent in the 
form of germs than in the adult state. Of 100 bacteri- 
form organisms found in rain, on an average 60 are 
micrococci, 25 bacilli, and 15 true bacteria. But the 
numbers here given are subject to great variation in 
different falls of rain: the bacilli may be more numerous 
than the micrococci, the true bacteria being almost 
always fewest in number. Dr. Miquel calculates that 
during a year at Montsouris 4,000,000 of bacteria are 
carried down in the rain to each square metre of surface. 
This number, though not probably representing anything 
like the real figure, demonstrates that rain is a powerful 
agent in diffusing aérial bacteria and fungi. We have 
yet much to learn as to the part these organisms undoubt- 
edly play when diffused into the soil, in altering or re- 
arranging its component parts or constituents so as to 
render it more fit for sustaining vegetable life and 
growth. 
The methods and apparatus employed by Dr. Miquel 
in his researches are very fully explained, and contrasted 
with other methods—especially those employed by Dr. 
Koch and other German observers—in terms that are 
not exactly those which a strict regard for international 
courtesy would dictate. It is somewhat of a reproach to 
bacteriologists that their leading authorities in all 
countries appear unable to keep clear of controversies 
which are conducted with an acrimony and animus more 
instructive than seemly. International jealousy would 
appear to lie at the root of much of this evil, and is 
plainly discernible in the writings of some of the ablest 
masters of the science. 
THE RECENT VOLCANIC ERUPTION IN 
NEW ZEALAND 
NTIL the report of a trained geologist has been re- 
ceived we must be content with the narratives, often 
conflicting, of the surveyors and of the Press corre- 
spondents who hurried to the scene of the great 
catastrophe that has recently devastated the wonderland 
of New Zealand. In the meantime, however, it is possible 
from the various accounts to trace the leading features of 
the eruption, and to note their resemblance to those of 
other recorded volcanic outbursts. It is impossible not 
to be struck with the analogy between the phenomena 
exhibited last June in New Zealand and those that 
accompanied the great Vesuvian eruption in the first 
century of our era. In both instances a mountain which 
had never been known to be an active volcano suddenly 
exploded with terrific violence, filling the air with ashes 
and stones. At each locality there were the premonitory 
earthquakes, the thick black pall of volcanic cloud hang- 
ing over the mountain, the descent of dust, sand, and hot 
stones, the discharge of mud, with, so far as known, no 
outflow of lava, and the overwhelming of an inhabited 
district under a deep covering of loose volcanic debris. 
In a region so subject to earthquake shocks as that 
which crosses the centre of the North Island of New 
Zealand in a north-east and south-west direction, it was 
natural that no special attention should have been given 
to any greater frequency or violence of the shocks before 
the date of this volcanic eruption. But no doubt facts 
bearing on this subject have been noted by local ob- 
servers and will in due course be published. From the 
newspaper accounts, indeed, there would appear to have 
been various precursory indications which in the light of 
subsequent events may not have been without import- 
ance. It is said, for instance, that the extinct volcano 
Ruapehu, the highest peak in the North Island, which 
since the discovery of New Zealand has never been known 
to manifest any activity, began to steam at the top some 
three weeks before the eruption. A fortnight previous to 
the catastrophe a wave 3 feet high suddenly arose on the 
Lake Tarawera, lying at the foot of the mountain of the 
same name, and in the very focus of the subsequent dis- 
turbance, and washed the boats out of the boat-houses. 
Doubtless there were other premonitory symptoms, be- 
sides earthquake activity, of the approaching event, 
though only a few days before their destruction, the 
famous White and Pink Terraces were visited by a party 
of tourists who observed no unusual vigour in the hot 
springs there, nor any indication whatever that these 
fairy-like deposits were so soon to be the theatre of violent 
volcanic energy. 
About half an hour after midnight on the morning of 
June Io the earthquake shocks that are familiar to the 
inhabitants of the Lake District assumed an altogether 
unusual vigour and frequency. At the settlement of 
Wairoa, which is about five miles from the warm lake 
and sinter terraces of Rotomahana, the ground shook 
violently for an hour or more, the more powerful shocks 
following each other at intervals of about ten minutes. 
The alarmed inhabitants, startled from sleep, ran out of 
their houses or clung to each other inside for mutual 
assistance and encouragement. At last, a few minutes 
after 2 a.m., a shock of exceptional severity was followed 
by a deafening roar, and suddenly what is described as a 
“pillar of fire” rose up from the crest of the mountain 
| range some five or six miles eastward on the opposite side 
of Lake Tarawera. The top of Mount Tarawera (about 
2000 feet high) had been blown into the air, leaving a 
huge chasm on the flank of the mountain. The glow of 
the white-hot lava in the interior ruddied the sky for miles 
around. Thousands of blocks of glowing lava described 
as ‘‘fire-balls” were shot into the air. The canopy of 
dark ashes that soon gathered over the mountain and 
spread out for miles around became the theatre of a 
violent electrical storm. It seemed to be torn asunder 
| with incessant flashes of lightning, and the continuous 
peals of thunder, mingling with the bellowing of the vol- 
cano, increased the terror of the night. 
That an eruption should ever take place from the three 
| huge truncated cones that frown over Lake Tarawera was 
not regarded by geologists as a future probability. They 
had been extinct even from the times of early Maori 
tradition. To their solitary and mysterious summits the 
natives had probably for centuries been accustomed to 
carry their dead. The bones of many successive genera- 
tions lay bleaching on that high lonely plateau, which had 
thus come to possess a peculiar sanctity in the eyes of the 
Maoris, who would not willingly allow a white man to 
approach it. Not only were these great cones to all 
appearance extinct, but the volcanic action of the whole 
district was of that type of waning energy which geolo- 
