Clusters and Nebulae* 259 



which, having a more hazy aspect than the rest, will be recog- 

 nized at once as a nebula by the naked eye in a clear nights 

 It is singular, therefore, that it should not have been included 

 among the " nebulosse " of the ancients ; and still more singular 

 that Galileo, in making the earliest telescopic delineation of ihis- 

 region of the sky, including the very stars in question, should. 

 have missed it ; for small as his instrument was, it was abun- 

 dantly adequate to disclose to him a marvellous appearance in 

 the midst of them. We can only suppose that he may haYe- 

 mistaken it for the effect of moisture upon his eye-glass, but if 

 so, his examination must have been a very cursory one: ancl 

 this, indeed, we should deduce from the roughness of his sketchy 

 unless, as is so frequently the case, engravers and copyists- 

 may have been in fault. The first notice of it which has been 

 found is a correct though incidental description of it by Cysatus- 

 shortly after, who compared with it the telescopic aspect of the- 

 grand comet of 1618. Huygens, not being aware of this r 

 announced it in 1656 as a discovery, the like of which he had 

 not been able to observe anywhere else among the stars, and. 

 sketched it roughly with a power of 100 in his 23 feet refractor. 

 His impression was that no telescopes but his would show it ; a 

 curious example of the amount of self-deception which may 

 result from unchallenged success, for we cannot imagine that 

 the object was less visible to the naked eye then than now.. 

 He saw, however, as it appears, only three of the stars in the- 

 trapezium, which forms so conspicuous a centre-piece; the 4th. 

 was added by Picart in 1673.* It was natural that so remark- 

 able an object should attract much notice, and many descrip- 

 tions and figures by the earlier astronomers are extant; but for 

 want of optical power their results are of little value. Sir W. 

 Herschel figured it in 1774; it was the first object viewed 

 with his 40 feet reflector in 1787 ; and he gave another design 

 in 1811 : Schroter represented it in 1794 ; Sir J. Herschel in 

 1824, and again at a greater altitude and in a clearer sky at 

 the Cape of Good Hope in 1837; and among other modern 

 observers, the Earl of Rosse, Lamont, Lassell, Bond, LiapounoVy 

 Struve, and Secchi, have directed much attention to it. Not- 

 withstanding the magnificent instrumental means and unques- 

 tioned ability brought to bear upon it by these great astronomers^. 

 their representations are not altogether accordant, and, gene- 

 rally speaking, they are not fully satisfied with each other's- 

 work. There must indeed be always a margin of uncertainty- 

 left as to these ill-defined and cloudy patches; and Sir J.. 



* Arago says, by Dominic Cassini; but -without reference: andtbig seeias im- 

 probable, as Mairan, who gives the exact date of Picart's discovery (March 20), 

 makes no mention of Cassini's. Picart's observation remained, however, in MS*, 

 till 1731. Cassini died in 1712. 



