" The comparison of comets to lances and swords
was, however, in the Middle Ages, very common in all languages. The great
comet of 1500, which was visible from April to June, was always termed by
the Italian writers of that time 'il Signor Astone' (see my 'Examen Critique
de l'Hist. de la G??ographie', t. v., p. 80). All the hypotheses that have
been advanced to show that Descartes (Cassini, p. 230; Mairan, p. 16), and
even Kepler (Delambre, t. i., p. 601), were acquainted with the zodiacal
light, appear to me altogether untenable. Descartes ('Principes', iii.,
art. 136, 137) is very obscure in his remarks on comets, observing that
their tails are formed "by oblique rays, which, falling on different parts
of the planetary orbs, strike the eye laterally by extraordinary
refraction," and that they might be seen morning and evening, "like a long
beam," when the Sun is between the comet and the Earth. This passage no
more refers to the zodiacal light than those in which Kepler ('Epit. Astron.
Copernican??', t. i., p. 57, and t. ii., p. 893) speaks of the existence of
a solar atmosphere (limbus circa solem, coma lucida), which, in eclipses of
the Sun, prevents it "from being quite night:" and even more uncertain, or
indeed erroneous, is the assumption that the "trabes quas [Greek word]
vocant" (Plin.
Pages:
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290