380 COSMOS. 



observed a group of this kind on the 20th of July, 1643, which 

 covered the third part of the Sun's disc) have always been 

 accompanied by numerous faculoe, I am not much disposed to 



on the contrary, perfect uniformity. The o^/ta, the dappled 

 surface, is expressly ascribed to light clouds, the atmosphere 

 (the scholiast of Arastus says, to the thickness of the air) ; 

 hence we always hear of the morning and evening Sun, 

 because their disc, independently of all Sun-spots, are sup- 

 posed, even in the present day, according to an old belief, 

 not wholly unworthy of regard, to give notice to the farmer 

 and the mariner, as diaphanometera, of coming changes of 

 weather. The Sun's disc, on the horizon, gives an indication 

 of the condition of the lower atmospheric strata which are 

 nearer the Earth. The first of the Sun-spots noticed in the 

 text as visible to the naked eye, and falsely regarded in the 

 years 807 and 840 as transits of Mercury and Venus, is 

 recorded in the great historical collection of Justus Reuberus, 

 Veteres Scrip tores (1726), in the section Annales Regum 

 Francorum Piping Karoli Magni et Ludovici, a quodam ejus 

 cetatis Astronomo, Ludovici regis domestico, conscripti, p. 58. 

 These annals were originally ascribed to a Benedictine monk 

 (p. 28); but, subsequently, and correctly, to the celebrated 

 Eginhard, Charlemagne's secretary. See Annales Einhardi, 

 in Pertz, Monumenta Germanics historica, Script, torn. i. p. 

 194. The following is the passage referred to: u DCCCCVII. 

 Stella Mercurii xvi kal. April, visa est in Sole qualis parva 

 macula nigra, paululum superius medio centro ejusdem sideris, 

 qua a nobis octo dies conspicata est; sed quando primum 

 intravit vel exivit, nubibus impedientibus, minime notare 

 potuimus." " On the 15th of March, DCCCCVII., Mercury 

 appeared to be a small black spot on the Sun, a little above 

 his centre, and was visible to us in that position for eight 

 days ; but, owing to the obstruction offered by the clouds, we 

 were not able to see either when it reached or left that 

 place." The so-called transit of Venus, recorded by the 

 Arabian astronomers, is noticed by Simon Assemanus, in the 

 Introduction to* the Globus Caleztis Cufico-Arabicus Veliterni 

 Musei Borgiani, 1790, p. xxxviii: "Anno Hegyrse 225, 

 regnante Almootasemo Chalifa, visa est in Sole prope medium 



