NOTES. xxir 



apparence) par les vapeurs et revenant au meme point d'ou elles etoiem 

 parties." 



( m ) p. 56. Prinz Adalbert von Preussen, Aus meinem Tagebuche, 1847, 

 S. 213. May the phenomenon described by me be connected with that 

 which Carlini observed at the passage of the Pole star, and its oscillations of 

 10 12 seconds, with the strongly-magnifying meridian telescope at Milan ? 

 (See Zach, Correspondance astronomique et geogr. Vol. ii. 1819, p. 84). 

 Brandes (Gehler's umgearb. phys. Worterb. Bd. iv. S. 549) is disposed to 

 refer them to mirage. The star-like light of the heliotrope has also been seen 

 by an excellent and practised observer, Colonel Baeyer, often uctuating hori- 

 zontally to and fro. 



( 115 ) p. 60. The distinguished merit as an artist of Constantino Huygens, 

 who was secretary to King William III., has only recently been placed in its 

 true light by Uptenbrock, in the Oratio de fratribus Christiano atque Con- 

 stantino Hugenio, artis dioptricse cultoribus, 1838 ; and by the learned 

 Director of the Leydeu Observatory, Professor Kaiser, in Schumacher's Astr. 

 Nachr. No. 592, S. 246. 



( 116 ) p. 60. Arago, in the Annuaire for 1844, p. 381. 



( 117 ) p. 60. " Nous avons place ces grands verres," says Dominique 

 Cassini, " tantot sur un grand mat, tantot sur la tourde bois venue de Marty ; 

 enfin nous les. avons mis dans un tuyau monte sur un support en forme 

 d'echelle a trois faces, ce qui a eu (dans la decouverte des satellites de Saturne) 

 le succes que nous en avions espere." (Delambre, Hist, de 1'Astr. moderne, 

 T. ii. p. 785.) These excessive lengths of optical instruments remind us of 

 the Arabian quadrants of about 190 feet radius, in the divided limb of which the 

 image of the sun fell, as in a gnomon, through a small round aperture. There 

 was such a quadrant at Samarcand, probably imitated from an earlier-con- 

 structed sextant of Al-Chokandi, about 60 feet high. Compare Sedillot, 

 Prolegomenes des Tables d'Oloug Beigh, 1847, p. Ivii. and cxxix. 



( 118 ) p. 60. Delambre, Hist, de 1'Astr. mod. T. ii. p. 594. The Capuchin 

 Monk, Schyrle von Rheita, a mystic, but highly experienced in optical matters, 

 had previously spoken, in his Oculus Enoch et Elise (Antv. 1645), of the 

 expected possibility of soon obtaining magnifying powers of 4000 for tele- 

 scopes, in order to give accurate maps of the Moon. Compare Kosmos, Bd. 

 ii. S. 511, Note 48 (English edition, p. cxvi. Note 488). 



( 119 ) p. 61. Edinb. Encyclopedia, Vol. xx. p. 479. 



( 1JO ) p. 61. Struve, Etudes d'Astr. stellaire, 1847, Note 59, p. 24. I 

 have preserved in the text the denominations of Herschel's reflectors of 40, 



