The Portland daily press., 1889-02-15
cHARTINc THE HEAVENS.
Photography as a Factor in Astro-
nomicaI Science.

Some months or more ago Congress was
asked to appropriate $4,000 for the purchase
of Photographic telescope and pointer, the
construction of building, domes. and mount
ings for the same, and for material for photo
graphic work, to enable the Naval Obserya
tory to take part in the proposed information
al project of charting by Photographic pro-
cess. This request was the outcome of the
Photographic Congress held at Paris
about two years ago, at which 1t was decided
that the very important work of charting the
sky by Photographic process should be begun
as soon as practicable. Our Government
was among the number who sent representa-
tives there, few of whom had been author
lied by their Governments to pledge them to
the support of the plans agreed upon, and
the majority of the others have since pre-
pared the means for sharing in the work.
Germany, Brazil, Chill, England, Mexico,
Spain and the Argentine Republic have each
one instrument in process of construction.
France has one in Paris already completed
and three others In the, hands Of a construc-
tor while far. off Australia, occupying most
important geographical position, has beaten
most Of the other countries in having two
photographed telescopes under way. Eng
lish, Austrian and Russian instrument max
ers have quite number of telescopes under
construction for other nations, so that nearly
all will be ready for work at about the same
time. Only one of the thirteen instruments
whose construction is assured has been pro.
vided by private means, and that exception
is in the case of an established observatory,
In other words the plan has been fully adj
opted by the majority Of foreign Govern.
ments, including all of those which maintain
important astronomical observatories.
There can be no question whatever as to
the expediency of participation in this work
| by the National Observatory, which In the
portion of North America most thicklY in
| habted is the only establishment of the kind
| on which the scientific world can rely for the
| larger portion of the general work of astrO-
nomical research, the magnitude of which,
| from financial point of view. is beyond the
resources of private observatOries. Another
| important reason for urging immediate action
| on the part of Congress was the fact that this
| country has done already so much In the way
| of photographing the heavens as to be styled
.sthe home of astronomical photography"
and that unless the amount asked for be
granted we are likely to be left without rep
resentation in this great international I'M
dertaking. 1t is for such objects as these
that the National Observatory has been cre-
ated and maintained by the Government,
and failure to utilize upon this important
occasion its superior appliances and trained
staff of observers would be fatal error.
Astronomical investigations within the
recollection OF the majority Of us went little
beyond facts connected with the motions of
the heavenly bodies and their relative posi-
tions. Later years, however, have seen such
tremendous changes in chemistry and the
arts that the advanced thought of half cen
fury age. has given place to inquiries into the
chemical constitution of the heavenly bodies,
the condition of the matter of which they are
composed, their temperature, spectra and
brilliancy. Among astronomers today the
most prominent place is held by photography
by which truly wonderful features have been
disclosed, and as the early development of
this art, as applied to astronomy, has been
largely American, the subject with our as
tronomers receives very warm interest and
most cordial support. 7.ofr s8sa Hi
Prof. Young. IN most able paper, has set
forth the various steps that have been taken
from the first announcement of Arago in 1899
to the French Academy of Sciences of the
great invention of Daguerrean which time
he proposed to use the new art to obtain
pictures of the moon-t0 the time of the sit
ting of the Astro-P Photographic Congress in
Paris. According to this authority the first
really valuable result of stellar photography
was obtained by Bond in 1857, who took a
long series of photographs of the double star
Mizar, which have been followed by others
of more or less Importance, including the
remarkable star chart of Henry Brothers in
in the United States, whose amazing photo
graphs OF stellar Spectra obtained at Cam
bridge were the most admired of all. The
steady exposure of the Photographic plate
for length of time, rendered possible
by the latest processes employed in the pre-
paration of the plates, brings to bear power
very much superior to that possible to be ex-
| cited by the human eye, so that objects faint
| or and fainter gradually leave their impress
| sion, and show exqiusitely the details impOs-
| sible to be otherwise reproduced. The i'm
4 portant time element also enters largely into
the calculation, as the newer process renders
| it possible to secure in a few hours what il
by former methods would most likely have
required months to accomplish.
The object of the combined action of as
trOnOmers throughout the world is to obtain
| perfect charts OF the seventy millions or sc
| of stars that can be seen by telescopes, and
the applications of photography will expedite
| the work, and at the same time give more
correct results, as among faults eliminated
| that of the personal equation, that always
enters so largely into astronomical work,
and error will be entirely done away with
In photographing the stars one popularity
that has been noticed particularly is thai
with similar plates exposed to a given sky
| space for an equal length of time and ap
parently with equal clearness of sky, there
| are surprising differences in the number oil
stars that can at any time be photographed
| Experiments for three successive years, be
| ginning In 1885, resulted in 1924, 5023 and
| 1926 stars being taken during an exposure
| of go minutes duration in each case, yet the
| third year shows over five times as many
stars as the first. The numerous circum
stances, mechanical, chemical, and atmos-
| pheric, acting differ emily at different times
when to the eye everything is apparently the
same, naturally tend TO multiply the Difficult
ties encountered by those who attempt the
mapping of the heavens. and quite probably
| some similar influences may have caused the
determination not to extend the limits Of the
magnitude of the stars of the Photographic
| chart beyond those already defined by the
| Congress. in spite of strong pressure brought
to bear to the contrary.
| The recent improvements in astronomical
photography permit many problems to be at
tackled in far more satisfactory manner
| than formerly, and among the probabilities
is the discovery of the much-discussed satel
lite Of the moon, If such really exists, or il
| will be conclusively proved that no such OBJ.
wolves about the moon. The wonderful
| nebula of Orion has been continually in
creased and it is more than probable that
additional sensitiveness will join the vari-
Gus masses into vast nebula of many de
grees In length.
One extremely interesting feature, says
Prof Young, in Photographic photometry is
the fact that the size of the image of stal
on Photographic star chart is found to de.
| pend upon its brightness. The image of 8
bright star is no blacker in the negative thar
| that of a faint one, but it is very singular
| fact that its image is larger and that the
measuring of these images will result In q
determination Of the relative brightness OF
all the stars of which impressions have been
taken. 1t would seem from this that astron-
omy, which is one of the oldest of the scien-
ces, is yet capable of advancement beyond
what was ever dreamed of ia the first part of
this century and that lit is as active and Wig
orous as ever, growing and expanding in all
directions with a futuIa before IL the plorv