Year: 1873

motions of the stars, telling which


are receding from and which ap
preaching towards US. This proc


turns upon the vibratory theory o


lig 1t. according to which light is


caused by exceedingly rapid mo-


tio1s of molecules. According tc


this theory the rays which strike tht


face of prism most rapidly are least


refracted from their course. If 9
body emitting light recedes rapidly


from prism less impulses will strike


the face of the Prism each second


than il it were standing still; if it ap.


proaches rapidly more impulses will


be received and transmitted. and the


lines in the spectrum of the light will


be bent in a direction opposite "a


that in which they will be bent if the


body be receding, because in Il c


first case the vibrations shifting the


prism with great velocity will be less


bent from their course than when the


luminous body is stationary, and in
the latter case will be more greatly
refracted. The spectrum of Sirius
shows that that star is receding from


the earth at the rate Of about thirty
or forty miles second Aldebaran
and others are. as Mr.. Higgins show
ed last summer, also receding, while
Arcturus is coming towards us with
a velocity of about filty-fve miles a
second. Some time ago Mr.. Proctor
asserted that certain FIVE stars in Ursa
Major had proper motion of their
own, and that if the spectroscope
should be turned upon them they
would be found to be going in the
same direction, and they have been
shown to be receding. Ifever a spec
troscobe shall be invented to take
cognizance of the thwart motions of
the stars vast and new field of knowl-
edge will be opened up. Thwart mo
tions can now be determined only by
comparing old astronomical tables
wi h new. and the observations must
be taken at least a hundred years
apart; the spectroscope can in ten
minutes do such work in regBrd to
motions to and from the earth. In
he solar eclipse of 1912 brilliant
Iro,uberances were noticed around
the limb of the moon at the moment
of total observation, and questions
arose as to their nature, which was
settled during the eclipse in India in
1868, When Lockyer aud Jansen and
Tennant saw the lines of the spectra
thus showing them to be Of incan-
descent gas; the spetra were so bright
it was thought they might be seen in
daylight, as Higgins bad said they
could be if the proluberances were gas
the experiment was tried and succeed.
ed; they may be examined every day
and their motions observed. The
spectrum of the chrOmosphere (of
which the protuberances are a part
is more complicated than it was once
thought to be, and only last summer
the speaker, while on a mountain
on the route of the Pacific Railroad,
had detected 273 bright lines; nor
has he any doubt that if it were pos.
sibl to get above the disturbing effect
Of the atmosphere, he would find the
whole solar spectrum reversed. The
changes in the chromosphere are as
rapid as those of the clouds on earth.
and by the means of measuring re
cession and approach already men
toned It can be toll when those char =
ges are taking place; sometimes the
line IN the spectrum will be bent one
way, sometimes another, and some
times broken up, and in this way the
speaker had measured masses of hy-
drogen coming towards the earth at
the rate of l50 and 200 miles a Sec
oud. During one Of his observations
he found violent disturbance at
particular time, and found that at
that instant violent magnetic storms
were raging on the earth. That night
there were brilliant displays of aurora
borealis, ,@and since then it has been
pretty we'll settled that disturbances
in the chromosphere instantly cause
changes in the earth. 1t
has been found from spectroscopic
observation that the temperature of
the cromosphere is sometimes low
enough to allow gasseS to combine =
In 1869 the corona was found to give
bright lines, showing it to be self-lu-
and is composed partly of
hydrogen. To conclude. 1t has
been shown by means of the spectre
scope within the last ten years that
the nebula and comets are seif-!a-
and therefore consists of
glowing gas; that some stars are re-
ceding from and others moving to-
wards us, and this splendid instru-
ment has detected the physical con-
,tituentS Of the sun. and its meteor
ology.