Saint Mary's beacon. [volume] (Leonard Town, Md.) 1867-1983, 1874-08-20

JwtN4lrxa % fH9 S3ARS.-Tho ouh.
}eee d the tvinkiisg e sfsss he's eseaRed Z
COED deal q stssssioe of lass ysas0. sad
sooe iuserestiag rssslss have bcea obtain.
ed A tsv yesrs ago the Italias astroao-
.mer. Reap;ehi. sasoeaesd' The. discovery
Of the sAsss u ssistillation. IN certain
DARK bssds vAisA: sees sesa 10 traverse
he spsetrsn of stsr. i1dSessiag ehanges
in the reftsnkIe1lies e sse. st1sephers,
from hot and cold strata. which pso9aeo
something Of the effect Of . passing mi
rage. A layer Of hot air would bend
rays less than the colder and deuser air
around. and thus the stars light would
not reach the observer. rays which trav-
ersed the hot stratum passing over his
head. and those which traverscd the cold
air below being bent % as to fall beneath
bis feet. As the rays Of different colors
are differently bout in their passage
through the air (the red rays being the
least rcfracted. } different parts Of stars
spectrum would Be thus cut o6 in success
sion as the relative temperatures Of the
layers Of air varied. Arago's not very
lucid explanation Of the phenomena. as
result of the interference Of light, is iu
this way completely disposed Of.
NJ. Montigny. Of Brussels, has been
investigating the amount Of scintillation
10 different stars BY the help Of an inge-
nious contrivancc. to which he gives the
name Of of.scinti.lomctcr. His plan is to
make use Of the persistence Of impressions
on the retina, BY causing thick plate Of
glass. mosntcd obliquely on an axis. par
allel to that Of the telescope used. and
6xcd just in front Of the eyepicce. to ro-
tate rapid y; the effect of this is to dis
place the stars image. to that. owing to
the varying inclination Of the glass plate.
the star appears to move in circle. which.
IL the rotation is rapid enough (shree or
four times in . second forms a couiin-
nous circle Of light. just as in the case Of
. burning stick whirled rapidly. The
changes in the color Of star will be seen
on this circle, the successive points Of
which give the appearance Of the object
at successive small fractions Of q second;
and in this way. BY counting the alterna.
tons Of co.or in the circumference Of this
circle of light. NJ. Moniigny has succeed.
ed in observing nearly two hundred alter
nations of color in second of time.
The point sough: to DO established was
the connection between these changes and
the constitution Of the stellar light. for
it Is easy 70 see that the rays which are
dcfcient cannot be acted on by undula.
tious Of the atmosphere. aud there will
therefore DO fewer changes Of color the
more dark bands there are in stars
spectrum. Now Sccchi has divided the
stars of which be has examined the spec
ira into four types. and NJ. Montigny has
observed the scintil!ations Of stars belong
ing to three Of these types. viz: blush
white stars exhibiting four black lines in
their spectrum; yellow stars. like our suu.
showing 6ne dark lines; aud orange stars,
which have spectrum somewhat resem-
bling . colonnsde. As far a the re-
suits obtained by NJ. Mon,igny 60.
it seems that the greatest amount Of
twinkling is to be found in the first type
(white stars. and the least in the third
type (orange stars.) and that the mere
brightness Of the star has no influence on the
phanomeua. But the principle Of combin-
ing observations ofdiherent nights with.
out any further correction. on which n
Moniigny has acted. is highly objcctional.
aud destroys our confidence in his conclu.
sions. The proper way Of treating such
measures is to arrange the stars in sequen-
ces representing the order Of scintillation.
Just as Sir John Herschel formed scqncn-
ces Of brightness As basis for his stand
ard magnitude Of stars.