The Greenville journal. [volume] (Greenville, Ohio) 1850-1918, 1907-07-11

astronomy, whereby bldT pOSlIlOns,
spectra type, the variability Of stars
etc, can be determined, has vastly in
creased wo1nan's opportunity for work
in this department of science, measur-
ing Photographic plates being a spe-
cialty for which she Is admirably
adapted, since patience, persistency
and absolute accuracy are required.
The plates to be measured are
crossed by a network Of lines forming
small squares impressed on the plate
by a second exposure, independent of
that to the sky. and developed along
with the star images. Instead of
measuring the position Of one star
with regard to another, we measure
the position of all the stars with ref
erence to the network of lines, tech
nically termed reseau. Each star is
referred to the crosslines of the net
work in its immediate neighborhood,
and the relation of the different parts
of the reseau is determined once for
all.
The method may be compared with
that by which a person finds his way
in New York city, where the streets
cross at right angles and are at nearly
uniform distances apart. He knows
how many blocks to pass going east
ward and how many blocks to pass
going north and when he comes to the
particular block in which his friend
lives there is further subdivision in
to houses with numbers to guide him.
On star photograph the streets are
the CROSSINGS of the reseau and the
blocks are squares formed by them.
The place of a star in a particular
block is all that need be measured by
the micrometer and the simple knowl-
edge of the place of the block COM
pletes the desired information.
In accordance with plan adopted
at a congress of astronomers which
met at Paris In 1887, 1S observatories
in various parts of the world combined
together to make a series of photo
graphs covering the entire sky. No
fewer than 100000 stars find q
Quired and most of these have now
been finished. The further measure
ment of the pictures and the drawing
up of vast printed star catalogue are
also well under way, and altogether nc
fewer than 100000 stars will find a
place in this our latest directory of the
heavens. There is certainly no lack OF
material for women computers!
Prof. Edward c. Pickering of the
Harvard observatory, Cambridge, is
carrying on independent work Of the
same kind in connection with the Are
quipa observatory. About 1000 photo
| graphs are taken of the southern
heavens every year. They are of two
Iinds-spectrum and chart. The lat
Ter contain on their surface of eight
by ten inches thousands of star points
the spectrum plates showing the
spectrum of each star. Such plate
must be examined very carefully, if by
any chance new stars are to be found
and the work is extremely tedious.
All the photographs sent to Harvard
observatory are examined by , Mrs
Fleming, under whose supervision {
number of women are constantly EN-
ployed in assisting with this work
Mrs. Margaret Patton Fleming wa:
born in Scotland in 1857. In 1879 shC
came to the United States and secured
employment at Harvard Observatory
as computer. She is now in chargt
of the department for examination O
the thousands of Photographic plates
taken with the Draper telescope. Ii
this pursuit Mrs. Fleming has discov
cred large number of variable stars
and confirmed the discovery of severa
new stars. She has been ably assisted
in her work by Misses A. c. Maury
L. D. Wells, E. F. Leland and M. c
Stevens, all of whom have succeeded
in discovering new stars on their OWL
account.