Year: 1873

LECTURE By PROF. @. f. BARKER-THE WONDERS


OF STELLAR sPECTROSCOPY.


Prof. George f. Barker of Yale College de-


vered tue fifth of the Cooper Union free Of sci
entifo lectures Saturday evening to exceedingly
large audience. The topic OF the evening was 1.-The
Revelations of the stars through the spectroscope"


The lecturer began by speaking Of the suns corona
This is a radiant light shooting out from the sun
in all directions When examined through the spectre
scope gives peculiar spectrum. 1t Is partly contin-
nous showing that the light must be due to solids or
quds or condensed gases but it also gives spectrum
Of its own which proves that it shines by its light
and not merely by that OF the sun. May
not the corona be gas thrown by vol
canic eruption from the sun It's spectrum has
been obtained 100000 miles from the suns edge and
peculiar line resembling one OF those given by
iron it is hardly possible to imagine the heat there
TO be such convert iron into vapor 1t has been
supposed be dueto the presence Of mpurty Of the
iron which our refined methods wholly unable
20 eradicate Three lines have also been found in the
spectrum Of the corona and they correspond with three
in that Of the boreas. There some reason for
suppOsing the corona TO be immense aurora; still
more reason however, for supposng it to be matter
thrown the Passing from the sun on our way
70 the stars We first encounter the planets These the
spectroscOpe shows shine by the reflected light OF the
sun The spectrum obtained from each is that Of the
sun, having, however peculiar absorption bands due to
the character Of the surrounding atmosphere.





these bands pointed out. Continuing on our way
said the lecturer We come to the comets Thse bodies
are intrudcrs the community of the solar system and
therefore have be sharply watched by the spectre
scopc U has been observed that the spectTa given by
these bodies differ from that Of the sun. This demon
strates that they SHINE by their light. Moreover
their specra consist OF coored bands, which show them
20 be gaseous Thus much for one or two stopping
places on way. The specra Of the stars were OBJ
served 10y Fraunhoer, and compared by him with the
Spectrum OF the The star spectTa may be exam
ined by the ordinary Instruments There however
the following difficulties in the way: First there are
only a few nights in the year when such observations
are practicable second the light which comes TO US is
very feeble third there being disk to be viewed as
IN the case Of the sum- the image OF the star appearing
merely as a luminous point in the most accurate tele-
scopes. must be elongated in direction while being
spread out in the other by the prism. This causes Its
spectrum 10 be still feebly luminous When all these
matters considered II is not be wondered at that
little known concerning these bodies but that so
much has discovered The spectra given by stars
are continuous and marked by dark lines We thus as
certain that these bodies have, like sun, photo
sphere or shell OF light and an abs0rptive atmosphere
surrounding them. All the lines present in the suns
spectrum cannot be found In those OF stars. In like
manner these bodies give spectra which contain lines
not be found in the solar spectrum The stars, there
fore contain substances not IN the sum- and the sun con-
talns substances not IN the stars.


diagram showing the speetra OF the stars Aldebarsn
and Alpha OfiOnis then thrown on the and
explained In the spectrum Of Aldebaran' he said the
first red and the last In the blue those of
hydrogeH There are hydrogen lines in Alpha orio
pis. We therefore infer that hydrogen exists IN AIDE
baran but in Alpha 0ronis In this way IT has been
shown that antimony bismuh and telnrun, which are
,ot in the sun, are IN AldebaraD. brlns
winch is three millions OF millions W miles
distant from us has been examined, and the
reseDce In 1t Of four elements which we have on the
rpl has been made known. The light which we thus
eIamine took q years 10 reach and although the
star Is equal in hgbtving power TO co suns Ike ours
ef the Hight which comes 70 US from is only one SIX
IoiliOnth Of that which receive frOm the
snY I'm snife OF these drawbacks. however, may
snslvZe this light and determine the presence OF sub
n the Star readily as we examine b OF cop
80 ore an the earth The spectrOscOpe has also been
spped 10 tae determination Of Tue direction and rate VI