The Minneapolis journal. [volume] (Minneapolis, Minn.) 1888-1939, 1902-06-07

New York, June lone OF the wonders
the weather bureau at Washington the
story of any seismic disturbance on any
portion of the globe in sixteen minutes
after it's occurrence, and no atmospheric
wave has any effect upon it.
The weather bureau seismoscope is a
pendulum with needle at the top. If one
attaches a weight to a lead pencil, with
the point held upward, against piece OF
paper, and then moves the weight around,
the idea may be underst God. There are
several kinds of seismoscopes, but the
principle of all is the samoa pendulum
whose supports rest upon slab OF cement
or stone partly buried in the earth. The
foundation is proof against superficial
earth Jars. ::
Df course the weight of the seismo-
scope is carefully balanced. The needle
has a plat mum point and it fits within a
platinum lined hole. The slightest trem-
or of the earth causes the balanced weight
to move. and of course that affects the
needle. If the point touches the rim of
Its Enclosure an electric circuit Is COM
pleted and a record is made on a revelv-
| ing drum Of paper. -
Passes Through the Earth.
The, wireless messages received by the
| seismoscope do rot follow the earth S
| surface. They come ri At through the
earth. This is proved by the fact that
there is only one impression ever re-
corded by the instrument. \. d.
One of the most remarkable things
about the seismoscope is the fact that it
| takes Just sixteen minutes for an earth
quake wave to reach Washington, or any
where else where there is an instrument
for4 that matter. The wave transmission
:. through the earth appears to be uniform
] This has been demonstrated time and
! time again.
| Whenever there is an earthquake In ia
! pan-they have about three day On ar
I average-it makes vastly greater dis.
| turbance on the other side Of the Worlt
than most pebDle imagine.
i If there is a good hard earthquake, the
ground in New York and Washington
| whether it Asupports a twenty story sky:
4 scraper or the national capitol, rises ant
| falls about three inches.
That is the estimate made by 2Johr
Milne, and he knows more about earth
uuakes and seismic disturbances general.
than any other man who has ever lived
i There isn't the slightest doubt abou
! the fact he declares. Whenever there il
! a big earthquake anywhere, the solit
i ground hereabouts rises and falls tire,
| inches.
The eart1ls crust undulates like waves
! of the sea. But people are not conscious
of the earth waves, because the waves arr
SO long One reason is that it takes
about fifteen seconds for the earth wav,
to lift and as many 70 descend. Then
too, the earth-waves are enormously long
probably as long as Manhattan islant
from crest to crest.
When it is understood that an earth
quake in Borneo or some other far of
place can make such a row in New Yorl
and Washington, the fact that instru
ments can record the disturbances ma,
| not seem SO remarkable.
Professor Mines Instrument.
Professor Milne has an ordinary seismo
4 scope at his home on the Isle of Wight
where. he studies earthquakes all owe
the world.
Z Resting on stone foundation is sor
of iron mast, from which is suspended
boom. This covers little slit that open
upon sensitized film. The rays Of
lamp are thrown upon the end of tn
boom by a mirror. The slightest move
ment makes that boom vibrate, and IT
movements are photographed automatical