August 26, 1886] 
NATORE 
393 
But I have been informed that at the whaling settlement 
of Tawaite, on the east entrance of Tory Channel, from 
six p.m. up to about eight p.m. on the evening of the 9th 
(the night preceding the eruption), loud booming reports 
were heard as through the earth. As these reports were 
previous to any symptom of the loud disturbances at 
Tarawera, this suggests that they may have resulted from 
a slight movement along the great fault-lines that traverse 
the North and South Islands in a north-easterly direc- 
tion ; and, in this case, the immediate cause of the Tara- 
wera outburst may be found in a local fracture resulting 
from such movement. 
“VIII. Premonitory Symptoms.—The only premonitory 
symptoms of the coming outburst which have been de- 
scribed were an oscillation in the level of Tarawera and 
Rotorua Lakes, and the occurrence of earthquakes for 
some months past in that district, where, as a rule, earth- 
quakes are rarely felt. But neither of these are very 
characteristic incidents, nor would it be safe on future 
occasions to base any expectation of an eruption on such 
phenomena alone. The increased activity of the geysers 
and hot springs during the past season has also been 
advanced as having been a symptom of an approaching 
outbreak ; but those who were most familiar with the 
district will agree that their variation was no greater than 
is usual under the influence of rapid changes of wind and 
atmospheric pressure. The reports of sympathetic out- 
breaks in other places along the line of volcanic energy 
from White Island to Ruapehu appear to be quite un- 
founded. The outburst has shown conclusively that the 
springs at Rotorua and Rotomahana are quite inde- 
pendent of each other, and of those at other places, thus 
confirming the observations made by Von Hochstetter 
long ago, that all the various points at which thermal 
springs occur are situated round the margins of lakes 
formed by subsidence of circular areas, and are not 
connected by an underground system of gravitational 
drainage. 
“IX. Conclusion.—From the foregoing sketch of the 
character of the eruption I think there can be little 
question that it is a purely hydro-thermal phenomenon, 
but on a gigantic scale; that it is quite local and not of 
deep-seated origin, and that all danger is past for the 
present, so far as one can venture to form an opinion on 
such a subject. The extraactivity of the wzas which has 
been observed is no doubt owing to the heavy rains that, 
on the 9th, set in after the longest period of drought 
which has been experienced in that district for many 
years, and probably the frequent earthquakes which have 
of late agitated the ground have contributed to this 
activity by stirring up the sources of the water-supply, 
and facilitating the access of drainage-waters to the 
sources of the heat. But beyond what may be accounted 
for in this manner I believe there is no increased dis- 
turbance at Rotorua, Wairakei, Taupo, and other places. 
The quiescent condition of Tongariro and Ngaurahoe 
was plainly shown by the manner in which we observed 
it to be enveloped in snow. Asa rule,on the scoria cone 
of Ngaurahoe, snow rarely lies, excepting in a few of the 
gullies, but melts almost as rapidly as it falls. On the 
morning of the 17th, however, the cone of Ngaurahoe was 
covered with a great mantle of snow; while the puzas on 
Tongariro showed less than their usual amount of steam 
escaping. The only fresh activity which may be reason- 
ably expected is that which I anticipate when sufficient 
rain has fallen to cause the overflow of Okaro Lake into 
the south end of the great fissure, as its former drainage 
outlet to the Rotomahana Lake appears to me to be com- 
pletely filled up. If this should occur, and a fresh ex- 
plosion takes place in consequence, it will be comparatively 
moderate in its effects, as, unlike Rotomahana, the soft, 
incoherent pumice deposits between the fissure and Okaro 
Lake are not sealed down by an enormous weight of 
siliceous sinter. 
“(For some time to come great variations must be 
expected in the activity of the newly-formed fuzas 
according to the manner in which changes occur in the 
atmospheric pressure ; but, unless it can be shown that 
any local change in the barometer is experienced which 
is not shared by the surrounding district, the barometer 
affords no indication as to whether an eruption is or is 
not imminent. One of the most unfortunate results of 
the eruption, in addition to the disastrous loss of life and 
the destruction of the country, is the disturbance of the 
sense of security which has grown up amongst those 
residing at the Hot Springs; and I believe that many 
persons are so thoroughly shaken by the horrors ex- 
perienced on the morning of the roth that they will not 
recover their equanimity until they have been for some 
time resident away from the sounds, smells, and shocks 
that characterise the district. “JAMES HECTOR” 
IN QUEST OF THE ORIGIN OF AN 
EPIDEMIC 
A our issue of the 8th ult. (vol. xxxiv. p. 213) we dwelt 
on certain general aspects of the reports lately laid 
before the President of the Local Government Board by 
the Medical Officer of the Department on milk-scarlatina, 
but these documents deserve more detailed consideration, 
for they show us our modern organisation for combating 
death and disease, by prevention, at its best. They show 
us, too, the men to whom the task of guarding public 
health is primarily committed at their best—patient, 
watchful, wary, tenacious of the thread of their investiga- 
tion, eliminating this or that doubtful element, until 
finally they have tracked their quarry to its lair. In 
reading Mr. Power’s report, we have been constantly 
reminded of that famous description of the contest be- 
tween the man and the gun in Hugo’s “ Toilers of the 
Sea.” Here the fight was man against disease, and the 
former has succeeded in his task. We shall endeavour 
in this article to show how Mr. Power, of the Local 
Government Board, succeeded in tracing, step by step, 
an epidemic of scarlatina to its source. 
On December 18, 1885, Mr. Winter Blyth, the Medical 
Officer of Health of St. Marylebone, reported to the 
Board an extensive outbreak of scarlatina in his district. 
This he believed to be associated with the distribution of 
milk from a certain retailer in South Marylebone, who 
obtained his supplies from two farms, but the occurrence 
of the scarlatina appeared to be coincident with the milk- 
distribution from a certain farm at Hendon. Mr. Blyth 
had himself visited this farm, and, with the assistance of 
Dr. Cameron, the Hendon Medical Officer of Health, 
had carefully examined it, but was quite unable to dis- 
cover in its sanitary circumstances or in the health of 
those employed about it any sort of clue to the cause of 
the infection of the milk, Accordingly he went with his 
story to the Local Government Board. It will be seen 
that Mr. Blyth had done his work exceedingly well: in 
one of the most crowded districts of London he had suc- 
ceeded in tracing the scarlatina to a farm at Hendon ; that 
is, he had made out a strong prima facte reason for sus- 
pecting this farm; he had put a clue into Mr. Power’s 
hands which he had not been able to follow any further 
himself. The first question for Mr. Power to answer was 
whether the Hendon farm was at fault or not. When this 
was answered it would be time enough to pursue the 
inquiry more minutely: it would be loss of time to try to 
dig out the fox unless it was first ascertained that he was 
in that particular earth. With this object, then, Mr. Power 
traced the milk from the Hendon farm to other milk-re- 
tailers in St. John’s Wood, St. Pancras, Hampstead, and 
Hendon itself. From each of these, except St. John’s 
Wood, the same story came. Until the end of November 
or beginning of December the district had for some 
months been exceptionally free from scarlatina, but about 
