Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1845-12-04

netic needle? Another argument, that the stream
ers were sometimes heard to give sound as of
some rushing fluid is evidently false for a rush
heard when a streamer became lighted up must
exist only in the sympathy of the eye and ear OF
the observer, for no allowance was made for the
time the sound would take to travel from the stream
err to the observer
The voyagers to the Arctic regions believed they
saw streamer descend between them and some
distant hills Since the duration of the impression
of light the retina is about one-seventh of a
second, a streamer lighted up from above, down
wards to the horizon terminated by the hills would
appear to pass below the summit of the hills TO an
eye following its downward course, although 1t
were really far beyond them. Such arguments as
the above must seem undeservng of serious retu-
tation, yet they have weighed more with leading
scientific men of the present day, than legitimate
investigations, is evidenced by the proceedings
of the British Association and the Transactions OF
the Royal Society
Trigonometrical measures of the more perma-
nent portions Of the phenomena are the only sure
method of determining the height above the earth's
surface, and the arches are the best suited of any
Of them
If b. C, d, f, were places on the earth's surface
and on the same magnetic meridian, A, the highest
point of the arch above the horizon, would be the
same for all the places (the arch being supposed
perpendicular to the plane of the paper and if seen
northward at any considerable altitude at b and c.
many miles distant from B and G, if the height D.
A did not exceed five miles, which is the greatest
height attributed to the light heecy clouds, and
more dense clouds being often under one mile high
Such an arch would appear considerably to the
southwark at L, few miles further north than ID.
Now no such great paralactic effect is noticed
The arches as well as the other appearances, are
seen at places more than 100 miles distant on the
same magnetic meridian, with only moderate
change of altitude above the horizon showing that
the height above the earths surface must be many
times what we have just supposed.
Several philosophers of the last century endeav-
ored, with data less perfect than we can now use
since the magnetic character is established, to find
the height and obtained results 1873 to zoos miles.
The discordance of these a strong argument
against them; but we that the auroral light
must exist at great difference Of height
The more trustworthy measures have been made
in this country, and have acquired greater degree
of certainty since the magnetic theory was devel-
oped The first in point Of date is that made by
Cavendish from various observations on the aurora
of the Odd Feb 1884 These gave the height to
be betweed - and II miles.
DIR. Dalton, whilst living at Kendall, re-discover
ed the connection of the meteor with the earths
magnetism, not knowing that it had been proposed
more than seventy years before by DR.. Haley
Upon this he made preparations, in injunction
with friend at Keswick, nearly twenty miles
distant on the same magnetic meridian, to obtain
correct data for trlgonometrical determination of
the height, and, favorable display occurring, in
which the arch stationary, the observations
gave the height $50 miles. The next calculation
was made by DR.. Dalton on the aurora of the 29th
March 1926, on which good observations were made
at places so distant in England and Scotland that
he considered the data the best which had been
procured they gave the height 100 miles.
Having watched the displays of the Aurora with
assiduty for several years, | at length obtained,
whilst living near Manchester, an observation of
an arch contemporaneous with another by DIR. Bur-
ney at Gosport on the 18th Sept. 1928. NIanches-
ter and Gosport being about 1913 miles on the mag
netic meridian, gave an excellent base, and the
height for the upper edge proved to be between 1877
and 2lS miles, allowing the utmost limits ac-
count of the arch being in motion. 1t was seen to
the north of the zenith at Gospor and to the south
of it at Manchester.
The auroral arch of the 18th Dec $780, was OBJ
served by DIR. Burney at Gosport and by Mr.. John
I Blackwal at Crumpsall Hall, near Manchester
The height for the upper edge came out 80 miles.
If the altitude at Gosport nearer the first de-
termination given by Dr. Buiney, the height ght
be l34 miles. The height Of the upper edge cal
culated by formula | had investigated for finding
the height and distance from observations of the
altitude of the arch above, and its extent on the
horizon, on the condition thati was part Of small
circle round the magnetic axis came out los miles
An arch Of an Aurora Borealis on the 2lst March
1883, was observed at Armagh by DIR. Robinson
at Athboy by Lord Darney, and at Edinburgh by
Professor Forbes. The data being furnished to me
by Professor Forbes and Dr. Robinson, calculated
its height from their observation to be 1876 miles
. nearly from Lord Darney's and Professor Forbess
observations, | found that, thirteen minutes fou
o seconds later its height l43 miles nearly. The
g arch, whilst proceeding southwark, may have de
d scended nearer the earhs surface, but Lord Darn
ley's time was not accurately marked to MAKE
no ar
n the same magnetic meridian and used the method
: of taking the differences Of the distances Of tn
n places from the magnetic pole, as the basis. Ii
e consequence of the reading of my paper at thu
O meeting Of the British Association at Cambridge
+ in 1888 on the last calculation of the last mention
s. ed Aurora discussion arose, in which Dr. Whe
e well and Professor Airy advocated its being at
f. low elevation A committee being formed, and in
is structons for observing drawn up and distributed
l. extensive observations were obtained on the tw
a magnificent displays which occurred on the l7t
Sept and the 18th Oct. 1888. Up to this time
believe no calculation of them has been published
j. Mr.. Airy, by a method entirely graphical, says
m found the height of the arches to be between lift
rs and sixty miles, that of the 18th Sept being prof.
ably the higher. Sat the same time, the ProfessC
e. expressed his conviction that the streamers in tn
Aurora of Sept 18th were connected with tn
4 clouds visible at Cambridge" Now, the streamel
ne were from the descriptions in the observations
II luehty OOiiHcStcu WIN Nulph SIouuS, oul pas
$, sage just quoted leaves us to conclude they wer
or the ordinary clouds.
a. From the observations on the 18th September,
d. find on calculation, the arch which occurred earle
of in the evening had the height OF its under edge
rs and of its upper edge n miles Later in the eve
ming faint stationary arch was observed at Yor
n and Gosport, on which good observations wer
he made, and which gave the height $50 miles.
ar We see that the Aurora exists only beyond tn
in ordinary limits assigned to the earth's atmospher
n forty fifty miles,, and that it takes place wit
IN this for inferior limit at much greater heights Il
in cause must therefore, be sought in extraneous
ne ter arriving within the influence of the earths mag
y netism or electro-magnetism.
ir | have before given an opinion, which still bC
n lieve to be the correct vew and that the phenomt
I'd ma of the Aurora Boreais are caused by gaseou
I'd matter much more rare than kncke's or Bela
ut comets, which in its path in space comes With
at the earth's influence Such gas or vapor, wit