Watertown republican. [volume] (Watertown, Wis.) 1860-1906, 1877-10-03
TIE DISCOVERY OF MARS'S MOONS.
What Professor Hall thinks of DIR. ORA
ner'S Alleged Discovery.

Professor Hall of the Naval Observa-
tory in this city. who discovered the
moons of Mars, says that early last
spring he was impressed With the prob
ability of the existence of satellite to
Mars, and determined to make close
search at the earliest opportunity. 1t
is we'll known how on the night of the
18th of August he observed strange
object near Mars, which after repeated
observations and measurements, the
discovery of not only one moon but
two, was confirmed. Between the 18th
and the 10th, when the weather was
unfavorable for successful observations,
he both hoped and feared, but his wife,
TO whom alone he communicated his
discovery, was enthusiastic and conf
dent While patiently waiting to con-
firm his discovery his generous DISPOSE
ton almost induced him to commune
cate his chances of success to his assO-
ciates, SO that all could share the honor,
but the thought of his many years of
labor without any luck convinced
him that it would be foolish to throw
away his first real good chance. His
discovery is of great importance in
science; in fact it is inferior to only two
il the century, namely, the discovery
of Neptune in 1916 by DR.. Gale of Ber-
lin, and that of the ring of small plan
cts, or asteroids, in 1891, continued by
Peters of Clinton, n Y, and Watson of
Ann Arbor, Michigan. Surprise is often
expressed that the moons of Mars were
not discovered long ago, since they are
now so easily visible.
Several good reasons account for the
late discovery-the present position of
Mars, the perfection of our large tele-
scope and the energy, ability, and
shrewdness of Professor Hall being by
no means the least important. Mars
passed its opposition on the night of the
5th of September, and was then ut its
nearest distance to the earth-abOut
thirty-thfee million miles. Favorable
oppositions also occurred in 1916 and
1862, but Mars was farther off then
than now The opposition ia 1892 will
be us favorable for observing as the
present one. Previously, when Mars
was in opposition, astronomers were de-
voting all their attention to making OBJ
servations to determine its parallax,
and hence the distance of the sun, and
also to make drawings One astrono-
mer, however, previous to Professor
Hall searched for moon of Mars
d. Arrest, in 1862. He, however, thought
that if Mars had satellite it would bear
the same relation to the planet as our
moon to the earth. Consequently he
searched too far off, and his field of OBJ
servation did not include the suspected
satellite or satellites, and he was there
fore unsuccessful. Professor Hall thinks
that if D'Arrest had pointed his tele-
scope nearer the planet he could not
have failed to make the desired discov-
cry. And, too, the largest and finest
telescopes have only been made since
Mars was last in position for successful
observation. Although the newly-dis
covered moons can now be seen with
an Indifferent telescope, it musttbe re-
membered that it takes a much larger
instrument to make a discovery than
to see it when it is known just exactly
where to look. The great object in hav-
ing large telescopes is to afford an album
dance of light, SO that faint objects as
we'll as distant ones can be seen. 1t was
principally for the purpose of observing
closely the faint satellites of the outer
planets that the present large telescope
was constructed.
twill be remembered that DR.. Henry
Draper who has Il private observatory
at Dobbs Ferry, on the Hudson River,
says he has discovered, in connection
with Professor Holden, a third satellite;
the other two discovered by Professor
Hall, being distinctly visible at the same
time. Professor Hall, however, search
ing several nights at the same time with
DIR. Draper, has failed to confirm the
discovery claimed by the latter. He
does not say the third is not there, but
simply that he is unable to find it. Mr..
S. W. Durham. prominent amateur
astronom er at Chicago, who has a very
superior refractor, reports that he has
been unable to find it. Hundreds of
telescopes all over the world are turned
upon Mars every clear night, and al
though the two satellites discovered by
Professor Hall are distinctly visible, no
one has as yet confirmed the claim of a
third When Dr. Draper first claimed
his discovery it was deemed very proba-
bic, for he has an immense rejecting
telescope, little, if any, inferior in power
to the large refractor here at the OBJ
servatory DIR. Draper did not use this
telescope, however, when he claimed to
have found the third satellite, as it was
rugged for perfecting his recent import
ant discovery of oxygen III the sun.
The astronomer most likely to see the
third satellite, if it exists, is Mr.. r. L..
J. Ellery, government astronomer at
Melbourne. He has imm ense rejecting
telescope, and Mars passes the meridian
nearer his zenith than ours.
The famous twenty-six inch quatorial
telescope. which played such an i'm
portant part in the late astronomical
success, was mounted in 1878, and was
placed in charge Of Professor Newcomb
and later of Professor Hail. The tube
is ofsssteel, one-sixteenth of an inch in
thickness near the ends, and one-eighth
in the middle, and is made in three sec
tons. 1t is about thirty-two feet In
length, the middle third being about
thirty-one inches in diameter. From
this middle third the tube gradually
tapers to about twenty-eight inches at
i ,,ol,,