The sun. [volume] (New York [N.Y.]) 1833-1916, 1905-08-27

Of the sun itself, and would put us in the
way Of thorough knowledge OF many
perplexing questions.
Photographs OF the corona will be taken
with cameras Of all sizes and conditions
1t is only necessary to have a good lens
either small or large, in order to take a
satisfactory picture.
The greater the focal length Of the camera
lens the greater will be the diameter of the
sun on the finished picture; the greater the
ratio Of focal length to aperture the quicker
will be the speed Of the lens Ordinary
hand cameras land many such will be used)
will give a photograph one-sixteenth to
one-eighth of an inch across, with the corona
extending out quite little distance further.
With good lens, such as are made by the
c. P. Goerz Company, these photographs,
small as they are, show a surprising amount
of detail
GREAT CAMERAS TO DE USED.
But to be able to study this detail closely
1t is necessary to have a photograph on a
larger scale. The Lick Observatory will
send out three big cameras, each Of the
same size, forty feet long, and photographs
with these will give the sun over four inches
in diameter. One Of these instruments will
go to Labrador. to be used by DR.. Heber D
Curtis; the second will be in Spain. to be
used by Prof. W. W. Campbell and Prof
c. D. Perrine, and the third will be in Egypt,
up the Nile, with Prof. w. j. Hussey.
The eclipse OCCURS in Labrador at sunrise,
in Spain shortly after noon, and in Egypt
near sunset, and the astronomers wish to
learn If there is any change in the form and
appearance OF the corona during the time
it will take the shadow to move from Labra-
dor across to the possessions Of the Khe-
dive. Such change, evidently, would be
easily detected by means Of photographs
taken on the same scale.
These three telescopes will be mounted in
such way that they will point directly
toward the sun when it is collapsed. Since
the sun Is continually moving. 1t Ia necessary
to have the Photographic plate moved by
clockwork to keep up with the motion OF
the sun.
The party from the United States Naval
three huge cameras. placed in a horizontal
position, however, and with moving
mirror to reflect the light Of the sun into the
telescopes. Two Of these cameras will be
Of the same size as those to he used by the
Lick obeervers-forty feet in length, with
lenses five inches in diameter.
One will be used in Spain by Prof. W. s.
Eichelberger and DR.. s. A. Mitchell, tho
other in Tunis by L. E. Jewell and W. w.
Dinwiddie. Another camera, greater than
these, capable Of taking a photograph OF
the sun over seven inches In diameter, will
be in the hands OF G. H. Peters, photographer
at the United States Government Observa-
tory.
WIRELESS MESSAGES FROM THE SUN.
The light of the corona Is brightest near
the edge Of the sun and gradually fades on
AS is we'll known IL IS impossible to have
the same Photographic plate with the same
exposure satisfactorily portray the strong
lights and the faint, and so it becomes nee
essary to make exposures short and long
to photograph the inner and outer corona
in all their detail.
To got the faint outlying streamers-
they have been traced to a distance of ten |
millions of miles from the surface OF the !
sun--a camera with big lens and short focal !,
length, six inches aperture and thirty-two |
in focal length, il to be used by DR.. Mitchell |
in Spain.
How wonderfully the Photographic plate |
has revolutionized eclipse observations in
giving permanent record that may he
studied, and studied at leisure, instead of
fleei1g impression made while the OBJ
server II under high tension and nervous.
But when speotroscope and Photographic |
plate are used together the di'ooveries
i've been nothing short Of amazing.
The spectroscope was first used at the
eclipse Of 1868, and has been used for less
han an hour altogether Mt cclpses. The
irst photograph Of the spectrum was taken
IA recently az 1906. Since that year, when
indeed the photographs were in their ex-
state, there have been only three
,clipses observed, those Of 1898, 1900 and
1901, which altogether have lasted about
.en minutes, yet In those ten minutes
have been secured which
,learly show tho constitution OF the suns
atmosphere.
These photographs are wireless messages
rom the sun, sent, not like Marconi mes
ages from a distance Of a few hundred
miles, but from distance Of $4,000 900
miles. In wireless telegraphy the electric
waves are received and interpreted by an
instrument properly attuned, and II the
,ode is UNDERWOOD, it is possible to find out
what the operator hundreds Of miles away
s saying.
In wireless telegraphy from the sun the
comes by means Of the shorter