Northern Wisconsin advertiser. [volume] (Wabeno, Wis.) 1898-1925, 1903-08-27

examination of the plate, or series of
plates, that will reveal the full truth.
This is a privilege of which as
tronomers in various parts of the
world very frequently avail them
selves; for the value of the evidence
of these records cannot be easily over
estimated. An excellent example of
this appears in the information they
offer regarding Borelli's comet that is
now looking into the great dipper with
bubulous glance.
1t happens that photographs of the
region in which the comet first ap-
peared were taken at the observatory
in Cambridge on the nights of May %
and May SHAT is about three weeks
before the discovery-and, curiously
enough, there is a slight blur, which
may be the faint image of the distant
comet, on the plate for the former
date, though the one for May 80 shows
no such trace. Whether this blur
really is to be regarded as an initial
perhaps be determined when certain
negatives from Arequipa arrive to
furnish more definitely conclusive
evidence. 1t is known that the portion
of the sky in question was covered at
Arequpia on the dates of May 4, IA,
and 30, so that if the comet was bright
enough to come down." as the photo
grapher's term is, during the month
of May it should certainly appear on
one or more of the negatives made
at the Southern station. These have
not yet been received here but are
now on their way from South Ameri-
ca; for the present. Professor Pick
ering, with scientific caution, inclines
to the opinion that the comet was not
after June /.
So much by way of illustration of
the usefulness of the plates. How to
, render this unique collection of great
est value to astronomers generally by
placing in their hands some form of
useful copies has long been a per-
picking question to the Harvard
authorities. Indeed, the whole matter
of cooperation among astronomers is
so perplexing that Professor Pickering
was led recently to propose sort of
Astronomical trust" with provisions
for the endowment of special research
"a proposition which has been favor
ably received and is steadily making
progress. In the case of the collec-
ton of negatives it was proposed at
first to issue a series of engravings
on the same scale as the charts of the
great Durchmusterung, the star cata-
logue of the Germans, which is
classic among astronomical publica.
tions. But this plan, besides its great
expense, would not necessarily lead
to dependable results; that is to say,
the defects due to the use of ink and
paper would inevitably cause jevia-
lions from ideal accuracy. Then, too,
the difference in intensity between
black ink and white paper Is not
enough to represent fairly the diff
! ferences that occur on the glass
negative. The example also of the
failure of the so-called Paris plan"
under which the Photographic results
obtained by II European observatories
were to be printed regularly as OBJ
tanned may have had a lettering
effect, for 1t is no secret that only 800
out of the 1000 charts planned for
have been issued and that the under
taking has proved stupendous beyond
anybody's calculation.
some simple, workable scheme plain
ly must be evolved. Accordingly the
plan is to be tried of sending out
copies of the original negatives, in
the form of double contact prints.
These give a negative that for many
purposes is practically as useful in the
hands of anyone who is accustomed
to do astronomical work as the
original. The full set sent out consists
of 55 glass plates eight by ten inches.
covering the entire sky and contain
ing between one and two million stare.
some of these as faint as the twelfth
magnitude. The charge is less than
their actual cost, the balance being
paid from the advancement of
astronomical science fund of the Har-
ward observatory.