Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1889-12-08

scientific work, Prof Todd was enabled to
organize the expedition which consists OF 13
men with four assistants. The following
branches Of science are represented, astrono-
my, anthropology, biology including zoolo-
gy. entomology and botany, geology, meteor
0logy and Dhysics
Prof, Todd has charge Of the astronomical
work, and he is assisted by Profs. Loomis
and BigloE, OF Washington, Mr.. Jaeoby,
Of Columbia College, and Mr.. Davis, of
Princeton. All Of these gentlemen will be
engaged in making observations of the
eclipse. As has already been stated, the
eclipse will be total, by which is meant that
the moon will pass between the earth and
sun in such way as to totally obscure the
latter body. Partial eclipses also occur,
and the sun is then only partially obscured.
About 20 total solar cell pses occur in century
and in the present year there have been two
such eclipses. This has not happened for
over $50 years, and will not again occur for
over 100 years. The next total solar eclipse
available for astronomical observation will
take place in 1893. It has been the
custom of astronomers for something
over q century to observe solar eclipse
and probably about 100 total solar eclipses
have been accurately observed. The astron-
omers Of the expedition have been calculst-
ere to observe, but because of the uneer-
fainty Of the latitude and longitude of the
place where the observation is to be made
they experienced considerable difficulty.
According to what seems to be the best au-
fhority Tor the latitude and longitude the
eclipse will occur at o'clock SO minutes
and 81 seconds in the afternoon, which will
be O'Clock 45 minutes 30 seconds in the
morning by Washington time. With the
proper latitude and longitude the time of
the eclipse can be calculated to within one
or two seconds.
THREE MINUTES OF DARKNESS.
The duration OF the total eclipse will be
3 minutes and seconds, of the entire eclipse
about hours. There are several objects
IN making careful observations of a
total solar eclipse. One OF the principal is
% make Photographic records of all partial
phases. These will be valuable In correct
ing the tables of the motion of the moon
and this, of course, has an important bear
ing upon the subject of navigation.
Another and no less important aim of the
astronomers is to obtain photographs of the
corona of the sun. The corona is halo of
nilvery light that is seen around the sun
only during total eclipse, and never at any
other time. The object Of a study of the
corona Is to obtain better knowledge of the
constitution of the sun and surroundings
This has close relation to terrestrial meteor
ology, q science which is now in its infancy,
and one the knowledge Of which will greatly
conduce to human welfare.
Prof. Cleveland AbDe, Of the United
States Signal Service, is the meteorologist
Especial opportunities are offered for obser-
vations Of this kind, because Of the fact that
the route Of travel is longer than the usual
one, and partially optional. One of especial
lines Of research will be the systematic OBJ
servation of the movements of the air. The
emperature and pressure of the air will also
receive attention. Prof. Able uses several
methods for determining the movements of
the air. One is Dy means of anemo meters at
taehed 20 the npper part Of the shin, another
By the use Of balloons that are inflated with
hydrogen and set free, and q third with
peculiar mirrors arranged for observing tie
movements Of the clouds.
Mr.. =. D. Preston, of the coast survey,
vail DO the work in physics. The relative
forces Of gravity will be found at the differ
ent stations By means Of two reverse pendu-
lums Of invariable length. They will be
SLOWED 70 swing night and day, and the
1umbsr Of oscillations made in "a hours at
be separate stations being compared the
lative force Of gravity follow. The three
aRnetie elements declination, dip and in
usity viii be found by observations on
se successive days at each station If time
wits.
e. Harvey BrOvn. Of the National Mu-