NEBULiE 11 



circumstance which distinguished it from the nebulous stars 

 in Cancer, and from other nebulous clusters. All that could 

 DO recognized was a whitish glimmering appearance, bright- 

 er in the center, and fainter toward the margins. A\ith a di- 

 ameter of one fourth of a degree, the whole resembled a light 

 seen from a great distance through half-transparent horn 

 plates (similis fere spleiidoi' aj^paret, si a longinquo cande- 

 la ar dens per cornu pellucidiim de noetic ceniatur).^^ Si- 

 mon Marius hazards a conjecture whether this singular star 

 be not of recent formation, but will not give a decided opin 

 ion, although it strikes him as singular that Tycho Brahe, 

 who had enumerated all the stars in the girdle of Aiidromeda, 

 should have said nothing of this nehulosa. The Mundus Jo- 

 vialis, which first appeared in 1614, indicates, therefore, as I 

 have already observed elsewhere,* the difference between a 

 nebulous spot unresolvable by the telescopic powers of that 

 age, and a chister of stars,! to which the mutual proximity of 

 its numerous small stars, not visible to the naked eye, imparts 

 a nebulous luster. Notwithstanding the great improvements 

 made in optical instruments, the nebula in Andromeda was 

 considered for nearly two centuries and a half — as at its dis- 

 cover}^ — to be wholly devoid of stars, until two years since, the 

 transatlantic observer, George Bond, of Cambridge, in Massa- 

 chusetts, discovered 1500 small stars within the limits of the 

 nebula. I have not hesitated to class it among the stellar 

 clusters, althouofh the nucleus has not hitherto been resolved. -t 

 It is probably only to be ascribed to some singular acci- 

 dent that Galileo, who, when the Sidereus Nuntius appear- 

 ed in 1610, had already made frequent observations of the con- 

 stellation of Orion, should have subsequently mentioned, in 

 his Sas:siatore, no other nebulce in the firmament but those 

 which his own weak optical instruments had resolved into 

 stellar clusters, although he might long before have learned, 

 through the Mmuhis Jovialis, of the discovery of the starless 

 nebula in Andromeda. When he speaks of the nebulose del 

 Orionc e del Prescpe, he understands by the expression merely 

 "aggregations {coacervazioiii) oi innumerable small stars. "■^ 

 He successively delineates, under the deceptive designations of 

 nehidosce, capitis, cingidi, et ensis Orionis, clusters of stars, 



* Cosmos, vol. ii., p. 320. 



t Germ., Sternhaufeu ; French, amas d'etoiles. 

 X Cosmos, vol. iii., p. 142. 



§ Galilei notb che le Nebulose di Orione nnW altro erano clie wucchi t 

 cvacfvazioni d' innumerahili Sfelle.'^ — Nelli, Vita di Galilei, i , p. 208 



