St. Johnsbury Caledonian. [volume] (St. Johnsbury, Vt.) 1867-1919, 1892-02-18
SUN SPOT AND AURORA.
Some Interesting Points about both
these Phenomena.

Some Interesting Points about both
these Phenomena.
Written for the CALEDoNIAN1
Among the interesting statements
going the rounds of the press about
the sun spots and aurora of late, some
may be glad to know of observations
made with the telescope and spectre
scope used at the Academy. A care
full drawing was made of the spots
of the sun on Saturday and another
on Monday. These show that the
region about the spot now visible to
the properly shielded eye without a
telescope is one of great activity and
disturbance. The principal spot
seemed on Saturday to be the juno
ton of two large spots of the usual
type, as the penumbra was about
10000 miles long by perhaps one
half that width, while there were
two principal neuclei or deep black
portions, the eastern one itself cross
ed by bridge of the white photo
spheric material, as is often seen. On
Monday this eastern neucleus had
while the western one was greatly
reduced in size or broken up into
smaller fragments. The penumbra
also of the western portion was
greatly modified and broken up,
while numerous smaller neuclei,
perhaps dozen, were lying round
over a great area some of these hav-
ing little or no penumbra about
them. My estimate of the whole
disturbed region is not as large as
some statements would make it, but
it is safe to put it at 100000 miles
long by 10000 in width, or more
than twenty-five times the area of
all our earth's surface. Indeed, the
neuclei of this spot are 10000 to
| $1,000 miles in diameter, an area to
engulf our earth freely within its vast
scope. The area, named does not
include a line of smaller spots extend
ing to the northeast perhaps 2OO,-
900 miles. This line of spots, though
changed materially in those two
days, had not been the scene of such
violent commotion as in the greater
spot. Other spots were seen coming
on the eastern limb of the sun and
then had undergone considerable
change on Monday, while still others
had appeared. Near the centre, but
south of the equator, seen Mon
day, two small spots had made their
appearance.
was glad to avail myself of the
opportunity of seeing the aurora
with the new direct vision spectro-
scope lately procured in London for
the Academy. Schellen's Spectrum
Analysis gives the character of
various spectra noted by different
observers and they are found to vary
greatly. The one on Saturday gave
a spectrum much like one observed
by Zollner at Leipsic with a similar
instrument. Turning to the red
portion of the sky, a very dark red
line was seen, a bright line in the
yellow green, and faint, ill-detined
bands in the blue and violet Zollner
located a red line of greater refrangi-
bility than the lithium, but 1 judged
the red line to bee even further toward
the red end of the spectrum than the
lithium line. 1t was certainly quite
a distance from the D line Judged
of the position of the lines by turning
about and looking at the sun
spectrum from the moon. Where the
aurora was not red the same light
green line and faint bands beyond
were plainly visible, but no red line.
l also noted, as | find is recorded by
others, that in other parts of the sky
where no aurora was noticeable the
same light green line was distinctly
seen. The spectrum was notable for
entire absence of light in the region
between this red line and the light
green. S. H. BRACKETT.
NATURAL HISTORY SOCIETY.
The regular meeting of this society
was held in the Museum class room
on Tuesday evening and a varied and
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