ZODIACAL LIGHT. 139 



1661. The first observation of the phenomenon may have 

 been made two or three years prior to this period ; but, not- 

 Ivithstanding, tiie merit of having (in the spring of 1683) been 

 the first to investigate the phenomenon in all its relations in 

 space is incontestably due to Dominions Cassini. The light 

 which he saw at Bologna in 1668, and which was observed 

 at the same time in Persia by the celebrated traveler Char- 

 din (the court astrologers of Ispahan called this light, which 

 had never before been observed, nyzek, a small lance), was 

 not the zodiacal light, as has often been asserted,* but the 



and of the retardation of the extremes of the effects in meteorological 

 processes. It is, however, to be regretted that our Baconian-philosophy- 

 loving author, who was Lord Henry Somerset's chaplain, fell into the 

 same error as Bernardin de St. Pierre, and regarded the Earth as elon- 

 gated at the poles (see p. 148). At the first, he believes that the Earth 

 was spherical, but supposes that the uninterrupted and increasing addi- 

 tion of layers of ice at both poles has changed its figure ; and that, as the 

 ice is formed from water, the quantify of that Uquid is every where 

 diminishing. 



* Dominicus Cassini {Mem. de VAcad., t. viii., 1730, p. 188), and 

 Mairan {Aurore Bor., p. 16), have even maintained that the phenome- 

 non observed in Persia in 1668 was the zodiacal light. Delambre 

 {Hist, de VAstron. Moderne, t. ii., p. 742), in very decided terms, ascribes 

 the discovery of this light to the celebrated traveler Chardin ; but in the 

 Couronnement de Soliman, and in several passages of the narrative of his 

 travels (ed. de Langles, t. iv., p. 326 ; t. x., p. 97), he only applies the 

 term niazouk (nyzek), or "petite lance," to " tlie great and famous 

 comet which appeared over nearly the whole world in 1608, and whose 

 head was so hidden in the west that it could not be perceived in the 

 horizon of Ispahan" {Atlas dit Voyage de Chardin, Ta|p. iv. ; from the 

 observations at Schiraz). The head or nucleus of the comet was, how- 

 ever, visible in the Brazils and in India (Pingre, Comitogr., t. ii., p. 22). 

 Regardhig the conjectured identity of the last great comet of March, 

 1843, with this, which Cassini mistook for the zodiacal light, see Schum., 

 Astr. Nachr., 1843, No. 476 and 480. In Persian, the term "nizehi 

 fiteschin" (fiery spears or lances) is also applied to the rays of the ris- 

 ing or setting sun, in the same way as " nay^zik," according to Frey- 

 tag's Arabic Lexicon, signifies " stelluc cadentes." 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 

 fi-ora April to June,, was always termed by the Italian writers of that 

 time il Signor Astone (see my Examen Critique de V Hist, de la G6o- 

 graphic, t. v., p. 80). All the hypotheses that have been advanced to 

 ehow that Descartes (Cassini, p. 230; Mairan, p. 16), and even Kepler 

 (Delambre, t. i., p. 601), were acquainted with the zodiacal hght, ap- 

 pear to me altogether untenable. Descartes {Pnncipes, iii., art. 130, 

 137) is veiy 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 extraoi-dinary 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 

 mora refers to the :/odi;ical light than those in which Kepler {Epit. Aa- 



