The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-09-29


Kirchhoffs theory suggests that the common
cause is the existence of hydrogen in the at
mospheres of the sun and certain stars, and
its exercise Of an absorbing action on the
light emitted from beneath.
Now by careful and repeated observations
with telescope furnished with spectre
scope of high dispersive power, Mr.. Higgins
found that the line, the one selected for OBJ
servation, in the spectrum of Sirius did not
exactly coincide with the corresponding
bright line of hydrogen spark, which latter
agrees in position with the solar F. but was
little less refrangible, while preserving the
same general appearance. What conclusion,
then, are we to draw from the result? Surely
it would be most unreasonable to attribute
the dark lines in the spectra of the sun and
of Sirius to distinct causes, and to regard
their almost exact coincidence as purely for
tuitous, when we have in proper motion 0erd
cdatSdto account for minute difference. And
if, as Kirchhoff's labors render almost certain,
the dark solar line depends on the existence of
hydrogen in the atmosphere of our sun, we
are led to infer that that element, with which
the chemist working in his laboratory is so
familiar, exists and is subject to the same
physical laws in that distant star, so distant
that, judging by the most probable value of
its annual parallax, light which would go
seven times round our earth in one second
would take fourteen years to travel from the
star. What grand conception of the unity
of plan pervading the universe do such con-
clusions present to our minds
Assuming, then, that the small difference of
refrangibility observed between the solar and
that of Sirius is due to proper motion, Mr..
Higgins concludes from his measures of the
minute difference of position that at the time
of the observation Sirius was receding from
the earth at the rate of Al 4 miles per second
A part of this was due to the motion of the
earth in its orbit; and on deducting the orbital
velocity of the earth resolved in the direc-
tlon of line drawn from the star, there re-
mained 294 miles per second as the velocity
with which Sirius and our sun are mutually
receding from each other. Considering the
minuteness of the quantity on which the
result depends, it is satisfactory to find that
Mr.. Higgins results as to the motion of
Sirius have been confirmed by the observa-
tions of Father Secchi made at Rome with
different instrument.
The determination of radal proper motion
in this way is still in its infancy. 1t is worthy
of note that, unlike the detection of transver-
sal proper motion by change of angular posi-
ton, it is equally applicable to stars at all dis
tances, provided they are bright enough to
render the observations possible. 1t is con-
ceivable that the results of these observations
may one day lead to determination of the
III
more trustworthy than that which has been
deduced from changes of position, as being
founded on a broader induction, and not con-
fined to conclusions derived from the stars in
our neighborhood. Should even the solar
system and the nearer stars be drifting along
as Sir John Herschel suggests, with an OPP
proximately common motion, like notes in a
sunbeam, it is conceivable that the circum-
stance might thus be capable of detection.
To hat do IaI 60,
the possible progress of our knowledge when
we put together what has been accomplished
in different branches of sciencel
PHENOMENA OF A SOLAR ECLIPSE.
turn now to another recent application of
spectral analysis. The phenomenon OF
total solar eclipse is described by those who
have seen it as one of the most imposing that
can be witnessed The rarity of it's occur
renee and the shortness of its duration afford,
however, opportunity for only hasty study
of the phenomena which may then present
themselves Among these, one of the most
remarkable-seen, indeed before, but first
brought prominently into notice by the OBJ
servers who watched the eclipse of July 7,
1842-consists in a series of mountain-l like or
cloud-like luminous objects seen outside the
dark disk of the moon. These have been
seen in subsequent total eclipses, and more
specially studied, by means of photography,
by Mr.. Warren De La Rue, in the eclipse of
June IS, 1860. The result of the various
observations, and especially the study,
which could be made at leisure of
the photographs obtained by Mr.. De La
Rue, proved conclusively that these appen-
dages belong to the sun, not to the moon.
The photographs proved further their light
to be remarkable for actinic power. Since
that time the method of spectral analysis has
been elaborated; and it seemed likely that
additional information bearing on the nature
of these objects might be obtained by the
application of the spectroscope. Accordingly
various expeditions were equipped for the
purpose of observing the total solar eclipse
which was to happen on August II, 1868. In
our own country an equatorially- mounted
| telescope provided with a spectroscope was
| procured for the purpose by the Royal So
ciety, which was entrusted to Lieutenant
| (now Captain) Herschel, who was going out
| to india one of the countries crossed by the
line of the central shadow, Another expedi-
ton was organized by the Royal Astronomical
Society, under the auspices of Major Tenant
who was foremost in pressing on the atten.
| ton of scientific men the Importance of avail
ing themselves of the opportunity.
Shortly before the conclusion of the meet
! mo of the Association at Norwich last year,
the first results of the observations were made
known to the meeting through the agency cf
tbe electric telegraph. In the telegram sent
bv M Jansen to the President of the Royal
Society. it was announced that the spectrum of
the prominences was very remarkable, show
ing bright lines while that OF the corona
showed none Brief as the message neces-
salily was. one point Was settled The
,1,o,ooinences could not be clouds in the strict