The San Francisco call., 1901-11-05
CAMERAS REVEAL
SOLAR SECRETS
Crocker Expedition to
Sumatra Benefits
Science.

LICK OBSERVATORY, Nov. L-Direc-
tor w. w. Campbell OF Lick Observatory
has made public a report showing the re-
suits achieved by the expedition sent TO
Sumatra In May 10 observe the eclipse OF
the sun. The report shows that success
crowned Astronomer Perrine's efforts
and that many valuable photographs
were obtained. II says that tho general
conclusion to be drawn from the many
valuable results obtained by the expedi-
tion Is that the coronal structure sur
rounding the sun Is made up OF matter
probably very finely divided. elected from
the surface Of the sun with great veloci-
ties. just as We have matter elected now
and then from terrestrial volcanoes with
comparatively small velocities. This con-
clUsion is entirely In accord with that
reached by Professor Schaeberle in 1893
from an entirely distinct set OF facts.
Regarding the operations of the expedi-
tion, the report says In npart:
the expedition sent to Sumatra from the Lick
Observatory, through the generosity OF William
II. Crocker. to observe the total solar eclipse
ment has been unduly delayed from the fact
that the scientific apparatus and the nstronom- =
sidetracked at an Asiatic port for three months
and have but recently arrived at Mount Ham,
iitcn: The expedition was In charge OF Acting
the Lick Observatory.
a site for the observing station was selected
Padang. the capital Of sumatra. located at
about the middle OF the west coast OF the
island. The ten instruments were mounted and
in perfect adjustment week before the day
The morning OF the eclipse dawned CLOUDY
and the clouds persisted until the middle OF
the afternoon. At the time OF tho eclipse.
which occurred a few minutes after noon. the
clouds were comparatively thin. The negatives
were developed in the week following The
photographs have reached home in perfect con.
dition.
The negatives obtained with the forty-foo,
and the smaller cameras show the inner corona
clouds to Interfere. but the longest recorded
streamers are limited to about one and third
solar diameters... The photographs are full Of
interesting details. some Of their features be.
ing unique They will be very valuable in
studies looking TO an explanation Of the origin
-Four cameras OF eleven feet focal length were
used in making an examination for a possible
planet nearer to the sun than the planet Mer-
curry. Photographs OF the portion OF the sky
TO be occupied by the eclipsed sun were OBJ
graphs Of this same region OF the sky were We're
During the nrst half OF totality. when the
clouds were thin. the negatives show stars
ing the latter half OF the eclipse with thicker
clouds no stars were recorded For about half
the area TO be examined the results were,
therefore, very satisfactory: but for the other
half nothing was secured. comparison of
the photographs made here and In Sur1atra
should lead TO the detection Of any unknown
bodies.
The Photographic results from the polari-
graph and the two spectrographs were better
by virtue OF the clouds than they would have
been with a clear sky. In new work OF this
kind there IS very little to guide the observer
in forming his estimate Of the length OF ex-
posture required. In this case It has happened
that the reduced brightness OF the sky gave
proper density TO the negatives whereas with
a perfectly clear sky the photographs would
have been over-exposed and some OF the de-
sired results thereby lost.
These fields OF work are highly technical IN
their nature: but II will interest many 10
learn that the outer part OF the corona shows
a large percentage OF polarized light. whereas
the light OF the inner corona IN polarized much
less strongly. The conclusion to be drawn from
these results Is that the light from the outer
corona is largely reflected or diffused sunlight,
whereas that from the inner corona originates
from the incandesceDt corona itself.
The spectrum OF the outer corona ms recorded
on the photographs appears to be Identical with
the solar spectrum. whereas the spectrum OF
the inner corona fs entirely different, in that
Il shows no trace of dark lines. The concjusion
to be drawn from these extremely valuable
results In precisely the conclusion drawn from
the polarigraphic results. !