The Daily bulletin. [volume] (Honolulu [Hawaii]) 1882-1895, 1892-02-27
kSTRON0MlC FACTS
Vac iations Of the Short Pc
Rod in Latitude.
lnQutrins Into Remarkable Phase
of the Ea.th'S M>Vement.

At the anniversary meeting of the
Royal Society of London, November
80, 1891, Sir William Thompson pre-
sided and delivered his annual adj
dress. An abstract of the address is
given in Nature for December Sd.
From this abstract the TO lowing
paragraphs are taken. Further ex-
plantations of this matter may be
found in the qualifications of the
Astronomical Society of the Pacific"
vol. ii, page 1856, and vol. iii, page
254.
A fundamental Investigation in as
tronomy, of great Importance in res
pect to the primary observatories,
and of exceeding interest in connec-
ton with tidal, meteorological and
geological observations and specula
tons, has been defnitively entered
upon during the past year, and has
already given substantial results of a
most promising character. The In
ternational Geodetic Union, at its
last meeting in the autumn of 1890,
on the motion of Prof. Forester, of
Berlin, resolved to send an astrono-
mlcai expedition to Honolulu, which
is within 8 deg. to the opposite meri
dian to Berlin on deg. west of Ber-
lin) for the purpose of making a
twelve mouths series of observations
on latitude corresponding to twelve
months analogous observations TO be
made in the Royal Observatory, Der
lin. Accordingly DR.. Marcuse went
from Berlin, and, along with Mr..
Preston, sent by the Coast and Geo
detic Survey Department of the
United States, began making latitude
observations in Honolulu about the
beginning of June, 1891. In a letter
from Professor Forester, received a
few weeks ago, he tells me that he
has already received from DR.. Mar
cuse, at Honolulu, Hawaiian Islands,
a first installment of several hundred
determinations of latitude made dar-
ing the first three months of the pro-
posed year of observations; and that,
in comparing these results with the
corresponding results Of the Berlin
Observatory, he finds beyond doubt
that in these three months the lati-
tude increased in Berlin by one-third
of second, and decreased in Homo
lulu by almost exactly the same
amount. Thus, we have decisive
demonstration that the motion, rela-
lively to the earth, Of the earth s
instantaneous axis of rotation is the
cause of variations of latitude, which
had been observed in Berlin, Green
wioh and other great Ubservatories,
and which could not be wholly at
tributed 10 errors of observation.
This, Professor Forester remarks,
gives observational proof of dy-
namical conclusion contained in my
presidential address to Section A Of
the British Association at Glasgow in
1876, to the effect that irregular
movements of the earth's axis to the
extent of half second may be pro-
duced by the temporary changes of
sea level due to meteorological causes.
1t is proposed that four permanent
stations for regular and continued
observations of latitude, at places of
approximately equal latitude and on
meridians approximately 80 deg.
apart, should be established under
the auspices of the International
Geodetic Union. The reason for this
is that change in the instantaneous
axis OF rotation in the direction per-
pendicular to the meridian of any
one place would not alter its latitude,
but would alter the latitude of a
place 80 deg. from it in longitude,
by an amount equal to the angular
change of the position of the axis.
Thus two stations in meridians differ
ing by 80 degrees would theoretically
suffice, by observations of latitude,
TO determine the changes in the posi-
ton of the instantaneous axis; but
differenlial results, such as those
already obtained between Berlin and
Honolulu, differing by approximately
$50 degrees in longitude, are neces-
sary for eliminating errors of obser-
walton sufficiently to give satisfactory
and useful results. 1t is to be hoped
that England and all other great
nations in which science is cultivated
will cooperate with the international
Geodetic Union in this important
work.