The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1899-07-18
Registers In London Earthquakes
in Japan.
A MOST DELICATE INSTRUMENT 7
Local Experiments Under Profes-
This Marvellous Machine.

Professor Alexander of the Survey
has finally received the |
sometimes termed sels-
mometer, forwarded by Professor John
Milne of London to British Commis-
sioner Kenny, which has been lying in
the local custom house for months.
Mr.. Kenny left for Japan in January
and the letters announcing the send
ing of the seismograph had to be for
warded TO him. He wrote to Professor
MAXWELL about the matter and the lat
ter after more correspondence finally
turned the instrument over to the Sur
vey Department OF the Hawaiian gov
ernment.
The seismograph, derived from two
Greek words meaning earthquake
writer" is one of the most delicate
machines ever invented. Ii consists OF
an iron bed plate and stand carried OH
three leveling screws. Resting against
a needle point or pivot projecting from
the base of the stand, and held in
nearly horizontal position by tie, is
a light aluminium boom. Attached to
the outer end of this boom there is
small rectangular plate in which there
are two Slits, one of which i large and
the other small. Partly for the pur-
pose of balancing the weight of the
outer end of the boom, and partly for
obtaining the steady poin OF sels-
mograph between the attachment OF Il
tie to the pivot, a weighted cross-bar
is pivoted. When the boom swings to
the right or left, the rectangular plate
with it's Sits passes to the right and
left across a fixed slit in the lid of a
box, inside of which n two-inch strip
of bromide paper is being driven by
clockwork. Light from a lamp Is re-
fiected downwards by a mirror To cover
the whole of the latter slit. II how
ever. only enters the box to the right
and left of the floating plate ana
through the Sits in the same. When
| the boom is steady, the resulting pho
ltogram on the moving bromide paper
will be. when developed, that of white
band equal in width to that of the
moving plate, down the center of which
band are two very clearly defined
lines. one of which is thick and the
ether thin. To the right and left of
this white band the parer will have
been blackened by the light which en-
| tered at the two ends of the fixed slit.
On one edge Of one of these black
bands. at intervals of about two inches,
| there will be seen a series of white
marks which have been produced by
the plinute hand of a watch, the broad
ened extremity of which has hourly
at the half hour passed over the end
of the fixed slit. and for a period oi
about one minute eclipsed the light
Should the clock At any time have fail
| ed to drive the bromide strip with re-
gularity this will at once be seen by
differences in the distances between
successive time marks.
The instrument may be placed or
any solid pier in an observatory. or or
a specially constructed pier in the
ground floor of an ordinary dwelling
or in a hut or shed in the open. This
room should be dry and amply ventilat'
ed with shutters, through one OF which
red light can be admitted.
This marvellous little instrument,
said Professor w. d. Alexander yes
terday, costs fifty pounds in England.
1t is loaned to the Hawaiian Govern
ment on the recommendation of Pro-
fessor Davidson OF San Francisco by
Professor John Milne, the great Lon
don scientist, who, with Professor
Gray. invented il. All the expenses
connected with sending the instrument
TO Honolulu have been paid by Profes-
sor Milne.
The British Association for the
: Advancement of Science has a special
committee of scientists, composed OF
such eminent men as Lord Kelvin. Sir
+. J. Bramwell. Professor Knott and
others. whose object is To determine
the velocity with which motion is
propagated around. or. possibly
through. the earth. To attain this the
committee desire records from given
stations of the times at which various