The times., 1901-06-09

CAMBRIDGE. MASS June S.-A new
atlas of the moon is being prepared for
publication by Prof W. H Pickering OF
the Harvard Observatory, from material
obtained during the past season by means
of the Is6-foot telescope at the obserVa-
tors ternporarv astronomical station in
jamaica Although observations were IN
tarrupted bv the approach Of the rainy
Sc, ,on in May. the undertaking is sutfi-
cieDtIv advanced to be completed by mid
summer. and Prof Pickering has already
brought to Cambridge a full set of the
photographs necessary for the proposed
publication, although he hopes to be able
to secure better pictures to replace GER
tain of them which have proved not en-
tirely satisfactory.
The apparatus by which the photo
eraphs were taken has excited interest
all over the world, though undoubtedly
il would strike the average man at first
glance of inspection as being the most
impracticable ina ginabe. In the noun
tains Of Jamaica, at an altitude of 2."05
feet. two miles from Vaudeville, forty
from Kingston. in a particularly lonely
region, there are on a steep hillside two
buildings connected by a long box-like
structure set on poIes-which last con-
tains or rather is, the great lunar tele-
scope.
II is a fixed telescope and is placed
parallel to the axis of the earth. At the
equator its position would be horizontal.
but at Vaudeville. where the latitude is
eighteen degrees. the northern end of the
telescope must be raised at that angle,
so that the side of a hill of approximate
ly the right grade is utilized, the fact
that the instrument is thus in the posi-
ton of being pointed down hill being neu-
tralize6 by the further fact that the
celestial bodies are observed not directly
but through the medium of a mirror.
The little house at the foot of the hill
MAS a roof which is made in two parts
and is counter-balanced by weights so
that it can be pushed aside when obser-
Vations are to be made. A large mirror is
set on a concrete pedestal and attached
TO an. electric motor. so that while the
earth IS revolving from west to east the
mirror is being turned at the same rate
81 speed in the opposite direction. and
therefore may he kept fixed on any heav-
enjy object while it remains above the
horizon. On another pedestal, higher
than the mirror and opposite the aperture
OF the telescope, is a lens twelve inches
In diameter.
perfect cylinder of polished brass which
is always associated with a telescope in
the popular mind, but merely a rough
frame OF wood covered with wire netting
and builders paper, with a peaked roof
TO shed rain This box is not absolutely
iight-proof. but since the observations
are all made at night it serves its purpose
very well.
The upper end Of the box opens into
two-story building containing another
pedestal upon which may b> placed either
a Photographic plate holder. when it is
desired TO use the apparatus as camera
or an eye-piece when the apparatus is TO
be used visualIy. The plate holder is
moved automatically by an electric mo-
tor, and all the governing Instruments are
controllable by the observer in the upper
building, although, as matter OF con
venience in case of an accident to the
ma achinery, Prof. Pickering has had an
assistant in the lower building during
the progress Of observations.
BY an ingenious electrical device the
clock work governing the motors at the
lower end Of the telescope is regulated by
the observer l36 feet away so that he
may synchronize the movement OF the
mirror To follow the course Of a particu-
lar star. quite as easily as he may shift
its position to bring any portion Of th-
heavens in the field of view.
The mirrors, lenses. ard machinery of
the telescope were all taken from Cam
bridge early in October, but nearly three
months were spent in the work Of getting
ready, so that it was not until the morn
ing OF the first day Of the nesg century. a
lew minutes after midnight. that the FIRST
observations We're made and several DAYS
obtained The Pinch lens is used with
q stop reducing II 10 d 6-inch diameter
TOT tite photogTapic work, and exposures
% elEAl minutes are made for the quick
piates ana OF q minute and a half for
ti2e SLOW plates, the apparent inconsis,
tency Ia the times Of exposure being due
70 the fact that the more sensitive plates
are used Just after the lunar sunrise or
before the lunar sunset, when but little
llght Is obtainable from 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 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
We're also taken Of the whole lunar
sphere, so that altogether the new atlas
of the moon viii contain between 90 and
for the more convenient use Of telescopic
observers, for whose benefit the atlas is
largely intended. Larger plares are being
made and published at the Paris ObSer-
Vatory but the views taken there arc
confined TO one Of each section Of the
moon. instead Of the FIVE of each section
which Will be reproduced in Prof Picker
ing's new atlas.
Since the Paris Observatory IS doing its
particular work 20 the entire satisfaction
of the astronomers. Prof. Pickering has
practically confined his work TO these Sc
rial views, which have been attempted
else and which are likely to be
exceptionally useful in the Identification
of the moons various regions by reason
of the fact that they show them sys-
tematcally at different stages. Such Sc
rial views should also be OF assistance
IN studying the dark spots which appear
within some Of the craters, and which
seem TO Wa and Wane with the lunar
day anu also to change somewhat in char
acter during period Of years. II has
been suggested that these spots are
caused by plants OF some low order, Dos
sibly "A kind Of lichen. which blossom in
the sunlight and fade as sunset ap-
breaches.
While the lunar geography IS being
studied at Jamaica, il appears that the
local geography is not without it's pecu-
liar problems. The temporary station is |
In q lonely region surrounded by forests |
with but one other house In sight As II |
happens that no rain falls dur |
ing whole month the water supply Is a |
serious consideration Rain water is col |
lecred on cement platforms called barbe- |
c.ies. which are built primarily TOr the |
drying Of coffee and the pimentO berries |
which provide the allspice Of commerce.
The barbecue at the observatory is |
something like forty by eighty feet In |
size, slightly inclined 50 that the rainfall |
can be conducted TO a cement tank for /
Btorage II happens. however. that in the |
ne dew is exceedingly heavy |