Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-01-23
WAVES OF AIR.
From . Volcano They Travel Half Round
the World and Back.

the World and Back.
Prom the Leeds Mercury
Sir Robert Ball said that in any old atlas
they might look in vain for the name Of kra-
katoa, but every atlas that had been published
within the last few years would contain this
name appended TO little island in the Straits
OF Sunda- This little island was wholly nm
known to fame until the year 1855. when IL sud
denly sprsng into notoriety as the seat Of the
greatest volcanic outbreak OF which they had
any record Previous to this crisis in its his
tory twas known TO navicators who passed
through the Straits Of Sunda as beautiful
tropical island. 1t was uninhabited. though
occasionally visited by natives from the adjoin-
ing coasts of Sumatra and Java TO gather
the wild fruits that grew on it. BCt IN
1883 u began TO show symptoms of disturbance
that were wholly unusual TO it, 4 volcano,
which tradition had said was in action once
previously, began again, and speedily the
eruption increased until il began 10 attract in
terest in the surrounding parts. Some OF the
inhabitants of Batavia. 100 miles away. thought
1t might be nice place to have picnic. and
chartered q steamer for that purpose. The lit
tie information they had OF the early phases Of
the volcanic outbreak was derived from some
people who went on this picnic. Bat later on
some of the manifestations from Erakatoa in
creased and finally they eliminated in the vast
outbreak of August IS in that year. when. at 10
O'clock on Sunday morning, the eruption took
place, wholly unprecedented in the intensity Of
its character ana in the after effects with which
1t was followed
WHAT KRAKAroA MANS
1t would, perhaps, be rash to say that such
an outbreak never took place before. but no
outbreak Of volcano had ever been carefully
observed before which had anything like the
vehemence which krskstoa possessed To real
lie all that krakatoa meant they must not look
merely at the Straits Of Sunds- They had TO
look at ships logs all over the world, the
records of barometers from every continent
had to be examined. quantities of information
from the very antipoaes. even of hrakatoa.
had all to be brought together and focused
and discussed before they were able 20 realize
the mighty effects of that great convulsion.
The work occupied five or six years. and the
result had been published in an interesting
book by the Royal Society.
What we're the phenomena produced that
were OF worldwide Significance? When that
terrible upheaval took place tremendous
waves of the sea were set in motion, and one
OF the lines in which these waves Travelled was
from krakatoa to the Cape OF Good Hope.
There was a tide gauge TO show the height of
the water at the Cape of Good Hope. and they
saw that . wave which was not a tidal wave
had trayersed the whole OF that district. 1t
travelled right across the Indian ocean and
affected the tide gauge there, 5000 miles away.
The waves had been traced in other directions
also.
HUGE TIDAL WAVES.
On the low.lying shores of the islands near.
which we're densely inhabited, great waves
came in and swept the people away, and great
wave carried a vessel three miles high and dry
in the neighborhood Of Sumatra- Abiding to
the region over which the sounds Of the great
thunders of Krakatoa were heard, the lecturer
said that ships captains had a useful habit of
noting In their log anything unusual that
their attention WAS called to, ana at many
different points they heard sounds of an I'M
usual kind. They thought there was ship
in distress, and they made a note that
there were sounds like heavy guns being fred.
In the middle of Australia. also, the shepherds
were startled by the sound of heavy firing, and
II was afterward discovered that 1t was the
thunder of Krakatoa, 1900 miles away, which
they heard At the Island of Rodriguez the
coast guardsman noted that he heard from the
eastward very heavy guns but these sounds
came not from a ship, but from krakatoa,
which was s, 200 miles away.
1t SO happened that krakatoa was nearly on
the equator. Suppose they took a pebble and
dropped il into the water they knew the rIppes
il made; or let them notice the disturbance that
was caused in water by the bursting of tor
pedoes when the rippies would be seen break
ing on the shore some miles away from the
spot where the explosion took place.
RIPPLEs IN THE AIR.
He was going to speak of ripples taking place
not in the ocean. but in the air, and here they
were speaking on a subject which Krakatoa
alone had taught them. They had no kno Wedge
| OF any phenomena like that he was going to
describe except in the records of kraka;oa
They knew that the earth had the atmosphere
folded round it and supposed that il was AL
perfectly at rest On that memorable day when
krakatoa went up in terrific explosion it started
an agitation In the air not very unlike the agi-
tation produced in water when pebble was
thrown into 1T, and it set up ripples or waves in
| the air which formeda series OF circles. These
| ripples spread thousands OF miles; they spread
right round the whole earth and then they
began to converge until all the waves came to-
| gether at Central America, the antipodes of
| hrakatoa- They rebounded and went back
again on hrakatoa. The energy of krakatoa
was expended, but not the energy of the waves
| Again they started and came back to kralatoa
Each time they took sixteen hours to travel
from krakatoa to the antipodes and sixteen
hours back again.
These waves gradually declined in intensity
| until the seventh time, when the mighty infiu-
| ence was at length exhausted, and the instru-
! ments failed to record them any further. They
learned that from the recording barorueters
erected in observatories all over the world
Every one Of these barometers showed the pas
sage OF the wave. The wave passed over the
whole of England; the fluctuation was observed
IN the barometer at Kew, and Prof Thorpe
showed that it was observed at Leeds and when
these barometer records were brought together
they were able to read the course of this
mighty wave which caused the earth to trem-
bic. 1t gave them an idea of the shock which
the earth received by the outbreak in that mis-
cradle island in the Straits Of Sunda. When
the outbreak took place it shot a column of
smoke and ashes into the air, and the captain
oil ship who was some seventy miles away saw
this mighty column He measured il with his
| sextant and found that the column was about
eighteen miles high.
krakatoa dust told them Q great deal that
| they did not know before After this dust
went up eighteen miles high it was caught bv a
current and was swept across the Indian ocean.
then across Africa, the Atlantic ocean. America
! the Pacific ocean, and SO back again to kraka-
| toa in thirteen days. That dust showed them
that there was a regular current of air sweeping
| round the equator in thirteen DAYS By the
time the great cloud Of dust had got back again
1t had become diffused little, but it started
| again and went round the earth in thirteen
days Ii became more and more diffused. and
during the third round it was noticed for half
the way, but 1t got so spread that they were
not able to follow ii as they were in the two
| previous rounds. Ii continued going round
| the earth until it spread into the temperate re-
gions, and then We were permitted 10 enjoy
| some of the glories OF Krakatoa.
Every one would remember the marvellous
| sunsets that adorned our skies during the No
yember and December following. At that time
| it was said that they were due to Krakatoa.
The explanation Of il was that the atmosphere
M