Planetary Nebula. 267 



equalled, and which is the brightest of all but Canopus 

 and Sirius ! It has since made a fresh jump and who 

 can say it will be the last ? 



One of the most beautiful objects in the southern 

 hemisphere is a pretty large, perfectly round, and very 

 well-defined planetary nebula, of a fine, full independent 

 blue colour the only object I have ever seen in the 

 heavens fairly entitled to be called independently blue, 

 i.e., not by contrast. Another superb and most striking 

 object is Lacaille's 30 Doradus, a nebula of great size in 

 the larger nubicula, of which it is impossible to give a 

 better idea than to compare it to a "true lover's knot," 

 or assemblage of nearly circular nebulous loops uniting 

 in a centre, in or near which is an exactly circular round 

 dark hole. Neither this nor the nebula about 77 Argus 

 have any, the slightest, resemblance to the representations 



given of them by Dunlop As you are so kind as to 



offer to obtain information on any points interesting to 

 me at Rome, here is one on which I earnestly desire to 

 obtain the means of forming a correct opinion, i.e., the 

 real powers and merits of De Vico's great refractor at the 

 Collegio Romano. De Vico's accounts of it appear to 

 me to have not a little of the extra-marvellous in them. 

 Saturn's two close satellites regularly observed eight 

 stars in the trapezium of Orion ! a Aquibe (as Schuma- 

 cher inquiringly writes to me) divided into three ! the 

 supernumerary divisions of Saturn's ring well seen, &c., 

 &c. And all by a Cauchoix refractor of eight inches ? I 

 fear me that these wonders are not for female eyes, the 

 good monks are too well aware of the penetrating quali- 

 ties of such optics to allow them entry within the seven- 

 fold walls of their Collegio. Has Somerville ever looked 

 through it? On his report I know I could quite rely. As 



