The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1901-06-09

a Photographic plate holder when it is de-
sired to use the apparatus a camera. or
an eye-piece, when the apparatus is to be
used usually. The plate holder is moved
automatically by an electric motor, and
all the governing instruments are control-
able by the observer in the upper building,
although, as a matter of convenience in
case of an accident to the machinery.
Professor Pickering has had an assistant
in the lower building during the progress of
observations. BY ingenious electrical
device the clock work governing the motors
at the lower end Of the telescope is regu-
lated by the observer 1876 feet away, so that
he may synchronize the movements of the
mirror TO follow the course of particular
star, quite as easily ne may shift its
position to bring any portion of the heavens
in the field of view.
THE MOON PHOTOGRAPHED
The mirrors, lenses and machinery of
the telescope were all taken from Cam
bridge early in October. but nearly three
months spent in the work of getting
ready. so that it was not until the morn
ing of the first day of the new century, a
few minutes after midnight, that the first
observations were made, and several days
obtained The tweve-inch lens is used
with stop" reducing it to a six-inches
diameter, for the Photographic work, and
exposures of eight minutes are made for
the quick plates and of a minute and a
half for the slow plates, the apparent in
consistency in the times of exposure being
due 10 the fact that the more sensitive
plates are used just after the lunar sun
the crescent Of the moon.
For Photographic purposes the moon was
divided into sixteen sections, and FIVE
views were taken of each section. Since
the lunar day is twenty-nine and a half
terrestrial days In length the first view
was taken at the lunar sunrise; the next
two days later, according to terrestrial
time; the next at the lunar moon the
next two days before the lunar sunset and
the last at the lunar sunset. Views were
also taken of the whole lunar sphere, so
that altogether the new atlas of the moon
will contain between ninety and one hun
dred plates arranged by sections on sheets
for the more convenient use of telescope
observers. for whose beneht the atlas is
largely intended. Larger plates are being
made and published at the Paris observa-
fined TO one of each section of the moon,
instead of the five of each section which
will be reproduced in Professor chickering's
new atlas. Since the Paris Observatory
is doing its particular work 10 the entire
satisfaction of the astronomers, Professor
Pickering has practically confined his work
TO these serial views. which have been at
tempted nowhere else and which are likely
10 be exceptionally useful in the identifca-
ton OF the moons various regions by rea-
son of the fact that they show them sys-
tematically at different stages. Such serial
views should also be of assistance in study
ing the dark spots which appear within
some OF the craters. and which seem 10
wax and wane with the lunar day and also
TO change somewhat in character during
a period OF years. 1t has been suggested
that these spots are caused by plants of
some low order possibly kind OF lichen.
which blossom in the sunlight and fade
as sunset approaches
SUCCESSFUL ENTERPRISE.
While the lunar geography is being
studied at jamaica. 1t appears that the
local geography y net without its pecu-