Boys' second book of inventionsBaker, Ray Stannard
Science
Boys' second book of inventions
Baker, Ray Stannard
Inventions; Technology -- Juvenile literature
as a Japanese makes a lacquered basket, was held in high esteem in
Japan, and for more than twenty years he studied earthquakes and
invented machines for recording them. Then he returned to his home in
England, where he is at work establishing earthquake stations in various
parts of the world, by means of which he expects to reduce earthquake
measurement to an exact science, an accomplishment which will have the
greatest practical value to the commercial interests of the world, as I
shall soon explain.
[Illustration: The Work of the Great Earthquake of 1891 in Neo Valley,
Japan.]
But first for a glimpse at the curious earthquake measurer itself. To
begin with, there are two kinds of instruments--one to measure near-by
disturbances, and the second to measure waves which come from great
distances. The former instrument was used by Professor Milne in Japan,
where earthquakes are frequent; the latter is used in England. The
technical name for the machine which measures distant disturbances
is the horizontal pendulum seismograph, and, like most wonderful
inventions, it is exceedingly simple in principle, yet doing its work
with marvellous delicacy and accuracy.
In brief, the central feature of the seismograph is a very finely poised
pendulum, which is jarred by the slightest disturbance of the earth, the
end of it being so arranged that a photograph is taken of every quiver.
Set a pendulum clock on the dining-table, jar the table, and the
pendulum will swing, indicating exactly with what force you have
disturbed the table. In exactly the same way the delicate pendulum of
the earthquake measurer indicates the shaking of the earth.
[Illustration: Diagram Showing Vertical and Horizontal Sections of the
More Sensitive of Professor Milne's Two Pendulums, or Seismographs.]
Public-domain text, read in full here on John Shaqi.
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