In
Camargo's manuscript 'Historia de Tlascala', the light rising in the east
almost to the zenith is, singularly enough, described as "sparkling, and as
if sown with stars." The description of this phenomenon, which lasted forty
days, can not in any way apply to volcanic eruptions of Popcatepetl, which
lies very near, in the southeastery direction. (Prescott, 'History of the
Conquest of Mesico', vol. i., p. 284.) Later commentators have confounded
this phenomenon, which Montezuma regarded as a warning of his misfortunes,
with the "estrella que humeava" (literally, 'which spring forth'; Mexican
'choloa, to leap or spring forth'). With respect to the connection of this
vapor with the star Citlal Choloha (Venus) and with "the mountain of the
star" (Citialtepetl, the volcano of Orizaba), see my 'Monumens', t. ii., p.
303.
This phenomenon, whose primordial antiquity can scarcely be doubted, and
which was first noticed in Europe by Childrey and Dominicus Cassini, is not
the luminous solar atmosphere itself, since this can not, in accordance with
mechanical laws, be more compressed than in the relation of 2 to 3, and
consequently can not be diffused beyond 9/20ths of Mercury's heliocentric
distance. These same laws teach us that the altitude of the extreme
boundaries of the atmosphere of a cosmical
p 141
body above its equator, that is to say, the point at which gravity and
centrifugal force are in equilibrium, must be the same as the altitude at
which a satellite would rotate round the central body simultaneously with
the diurnal revolution of the latter.
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