The morning call., 1893-12-02

is proportionate variation in latitude all
over the world. TWAS thought at first that
the variation was only local. but latterly
IL has been discovered that il was
periodical change, common to every
quarter of the globe. and that its duration
was 427 days. In other words. that the
variation would increase from the be-
ginning of that period up to the one-half,
or two hundred and thirteenth day, and
tbeu diminish until on the four hundred
and twenty-seventh day there would be no
variation.
To ascertain just the amount of the
variation caused by the webbing axis the
GeodetIc Association is making investiga-
tons. The association is an International
affair, but the Investigations have been
left Chiefly to the Americans and Germans.
Germany has placed DR.. Marruse in an
observatory in Honolulu. and close by is
+. ID. Preston in another observatory for
the United States. Over on this con tinent
we have Professor George Davidson and
bis assistant. Frank Edmonds. for San
Francisco and Edward Smith at Washing
ton, ID. G. By these means all-around-the-
world observations are expected.
The Importance of the work may be
illustrated by a possible contingency n
running an International boundary. Sup
posing that at the beginning Of the period
of 427 days the representatives of the
British Government determined the bound
airy between British Columbia and WASH
ington. setting up monuments accordingly.
Then SUBJ Ose that 213 days later the
United States representatives came along
and, having determined the boundary.
found that in no case did it coincide
with that laid down by the British sur
vey. The difference might lead to an in
ternati0nal conflict of words. il not of
weapons. All that, however, would be
avoided il the little variation" were
known in that locality and could be figured
on as plus or minus quantity to be added
or subtracted in the calculations.
1t had always been an axiom in obser-
vatories that the position of the observa-
tory itself was a fixed point whose posi-
ton was known and could be taken as
standard whereby to calculate the position
! of unknown objects. But this webbing"
of the earth's axis disturbs this little
theory and practically moves thu observa-
tory about every 427 days and the observa-
tory men have TO figure on this now.
But, as one OF them observed yesterday,
lit is not to be wondered at that the earth
wobbles little on its axis, when you con-
slider that ii is not fixed to anything but
| Just swings and turns freely in space"
So loca! astronomers are reconcied to
| the fact of this variation aud are hard on
the trail of its determination. The work
is very difficult and laborious, requiring
special instruments. Perhaps it is only
| thO SpSCldi QclCdCy VI III
| struments that have made possible the
solution of this problem which has been
pulling the scientific world for a long
| time. Astronomers would make an obser-
walton at some observatory and later repeat
the Identical work only TO OBTAIN decided
discrepancy. This would be repeated
elsewhere and would be ascribed to
the instruments, mutation or vibratory mo-
tlon of the axis and other causes. Now it
is conceded TO have been due TO the varia-
ti0n-a perfectly constant" change, so to
! speak, aud one capable of complete scien-
tic determination.
| In order to determine the latitude or the
declinarion of the zenith the use of the
zenith telescope is required. The zenith
| telescope was originally introduced by
Captain Andrew Talcott. but has since
been materially improved by Professor
Davidson and others.
Referring to the accompanying cut,
which exhibits the instrument as now con-
structed, briet and general description
| of it will suffice. The telescope has an
aperture Of about 9 centimeters f3b
inches), and focal length of about Lid
centimeters (45 ;nches). and admits of OBJ
serving with convenience stars as small
| as the sixth and half or seventh magni-
| tude. The magnifying DO wer used varies
between 60 and 120. The telescope-tube
| turns about q horizontal axis nearly l8
centimeters e inches) in length, and is
| balanced by weight in such manner as
To prevent unequal pressure and hexure
of the axis. This Is supplied with a strid-
ing level. and when horizontal the line of
| collmati0n Of the telescope will move on a
! vertical plane; 1t is perforated and pol