METEOROLOGY. 237 
Atlantic ocean, N. L. 28°, on the night of Dec. 13, 1803. At that time it 
was visible as a reddish lustre in the evening twilight, of fifteen degrees in 
height; subsequently it extended more and more even to the zenith, near 
which it was about four degrees broad, the whole forming a triangle, whose 
base resting on the horizon was from eight to ten degrees in length. 
The true character of this remarkable phenomenon is veiled in the 
greatest obscurity. Dominic Cassini, and, after him, Laplace, Schubert, 
and Poisson, assumed a ring encompassing the sun and forming the orbitual 
path of an innumerable host of small planetary bodies revolving around the 
sun. According to Fatio de Duillier, the zodiacal light bears a great resem- 
blance to that of the tail of a comet ; according to Euler it is identical with 
this latter. Mairan, with most of his followers, supposed it to be the sun’s 
atmosphere; Hutton referred it to the agency of electricity; Thomas 
Young derived it from ahighly rarefied atmosphere of light revolving around 
the sun with a far greater rapidity than the earth. Regner, however, 
showed that there could be no luminous atmosphere around the sun, else it 
would be visible in total eclipses of the sun: he supposed the zodiacal light 
to be nothing else than light attracted and condensed by the illuminated 
hemisphere of our earth, and thus made visible at night. All these 
hypotheses are more or less untenable, particularly that which supposes the 
zodiacal light to be the luminous atmosphere of the sun, since, according to 
mechanical laws, this cannot be flattened more than in the ratio of 2: 3, the 
greater axis being thus to the minor as3:2. According to this computation 
it could not extend to more than ths of Mercury’s orbit, while the zodiacal 
light extends beyond the earth’s orbit, and the ratio of the two axes is at 
least as 1:5, and sometimes still greater. Perhaps the theory of Humboldt 
as to the material origin of the zodiacal light is the most probable. He 
assumes a greatly flattened ring of highly rarefied matter, revolving freely 
in space between the orbit of Venus and Mars, and consisting of particles 
of ether or other matter, revolving, according to the planetary laws, 
around the sun, their light being either independent of or derived from 
the sun. 
On the Fiery Phenomena of the Air. 
Excluding the electric and magnetic meteors, namely, lightning and the 
aurora, there remain to be considered, under this head, various phenomena 
more or less puzzling in their character. The principal of these are the 
ignis fatuus, the shooting stars, and the balls of fire; the two latter probably 
- identical in their nature. 
The ignis fatuus, also known as Will-o’-the. wisp and Jack-o’-lantern, is 
the faint light or flame, generally about the size of that of a taper, which is 
occasionally seen to hover over the earth at a certain height in the atmo- 
sphere, and flickering here and there, sometimes vanishing almost entirely. 
It is at times accompanied by a slight smell of sulphur. These are most 
numerous in churchyards, marshy places, and other localities where dead 
411 
