354 COSMOS. 



process of the evolution of light, as it were a diminution of 

 intensity in the photosphere; 2. Obstructions (such as a 

 greater and denser formation of clouds) in the outermost 



626 A.D. According also to Abu'l-Farag. (Hist. Dynast. 

 pp. 94, 99), half of the Sun's disc continued obscured 

 for eight months. 



733 A.D. One year after the Arabs had been driven back 

 across the Pyrenees after the battle of Tours, the Sun 

 was so much darkened on the 19th of August, as to 

 excite universal terror. Schnurrer, Chron. theil i. 

 p. 164. 



807 A.D. A Sun-spot was observed, which was believed 

 to be the planet Mercury. Reuber, Vet. Script, p. 58 

 (see p. 375.) 



840 A.D. From the 28th of May to the 26th of August 

 (Assemani singularly enough gives the date of May, 

 839), the so-called transit of Venus across the Sun's 

 disc was observed. (See above, pp. 379-380.) The Chalif 

 Al-Motassem reigned from 834 to 841, when he was 

 succeeded by Harun-el-Watek, the ninth Chalif. 



934 A.D. In the valuable work Historia de Portugal, by 

 Faria y Souza, 1730, p. 147, I find the following pas- 

 sage: "En Portugal se vio sin luz la tierra por dos 

 meses. Avia el Sol perdido su splendor." The Earth 

 was without light for two months in Portugal, for the 

 Sun had lost its brightness. The heavens were then 

 opened in fissures " por fractura," by strong flashes of 

 lightning, when there was suddenly bright Sun-light. 



1091 A.D. On the 21st of September, the Sun was dark- 

 ened for three hours, and when the obscuration had 

 ceased, the Sun's disc still retained a peculiar colour. 

 " Fuit eclipsis Solis, 1 1 Kal. Octob. fere tres horas : 

 Sol circa meridiem dire nigrescebat." Martin Crusius, 

 Annales Suevici^ Francof. 1595, torn. i. p. 279; Schnurrer, 

 th. i. p. 219. 



1096 A.D. Sun-spots were seen by the naked eye on the 

 3rd of March. "Signum in Sole apparuit V, Nono 

 Marcii feria secunda incipientis quadragesimoG. Joh. 

 Staindelii, Presbyter! Pataviensis, Chronicon generale, 



