OC•EA^^ C DISCO V^ERIES. 281 



hei'oii the tcnninatioii of Mai^ellan's voyage of circumnaviga« 

 lion. He compares their mild effulgence to that of the Milky 

 Way. The larger cloud did not, however, escape the vigilance 

 of the Arabs, and it is probably the Avhite ox {El Bakar) of 

 their southern sky, the u-hite spot of which the astronomer 

 Abdyrrahman Sofi says that it could not be seen at Bagdad 

 or in northern Arabia, but at Tehama, and in the parallel of 

 the Straits of Bab-el-Mandeb. The Greeks and Romans, 

 who followed the same path under the Lagides and later, did 

 not observe, or, at least, make no mention, in their extant 

 writings, of a cloud of light, w4iich, nevertheless, between ll*^ 

 and 12^ north latitude, rose three degrees above the horizon 

 at the time of Ptolemy, and more than four degrees in that of 

 Abdurrahman, in the year 1000.=^ At the present daj'', the 

 altitude of the central part of the Nubecula major may be 

 about 5^ at Aden. The reason that seamen usually first see 

 the iNIagellanic clouds in much more southern latitudes, as, 

 for instance, near the equator, or even far to the south of it, 

 is probably to be ascribed to the character of the atmosphere, 

 and to the vapors near the horizon, which reflect white light. 

 In Southern Arabia, especially in the interior of the country, 

 the deep azure of the sky and the great dryness of the atmos- 

 phere must favor the recognition of the Magellanic clouds, as 

 we see exemplified by the visibility of comets' tails at daylight 

 between the tropics and in very southern latitudes. 



The arrangement of the stars near the antarctic pole into 

 new constellations was made in the seventeenth century. The 

 observations made with imperfect instruments by the Dutch 

 navigators Petrus Theodori of Erabden, and Friedrich Hout- 

 mann, who was a prisoner in Java and Sumatra to the King 

 of Bantam and Atschin (1596-1599), were incorporated in 

 the celestial charts of Hondius Bleaw (Jansonius Csesius) and 

 Bayer. 



* Pigafetta, Primo Viaggio intorno al Globo Terracqueo, publ. da C 

 Amoretti, 1800, p. 46 ; Ramnsio, vol. i., p. 355, c. ; Petr. Mart.. Ocean., 

 Dec. iii, lib. i., p. 217. (According to the events referred to by An- 

 ghiera, Dec. ii., lib. x, p. 204, and Dec. iii., lib. x., p. 232, the passage 

 in the Oceanica which speaks of the Magellanic clouds must have been 

 written between 1514 and 1516.) Andrea Corsali (Ramnsio, vol. i., 

 p. 177) also describes, in a letter to Giuliano de' Medici, the rotatoi^ 

 and translatory movement of " due nugolette di ragionevol grandezza.^ 

 The star which he repiesents between Nubecula major and minor ap 

 pears to me to be ,5 Hydras {Examen Crit., t. v., p. 234~2c3). Regard 

 ing Petrus Theodori oi'Embden, and Houtmann, the pupil of the math 

 ftmatician Plancius, see an historical article by Olbers, in Schumacher'^ 

 ■Sahrhuch fur 1840, s. 249 



