450 L. Troitveht— Physical Observations of Saturn. 



As Bond speaks of the [ 

 being perfectly elliptical," and ; 

 pected that it " was narrower in some places," it is to be inferred 

 that he had some faint glimpses of the phenomenon which I 

 have observed, and which possibly may be more conspicuous 

 now than twenty years ago. 



But the fact that this phenomenon has not been observed 

 earlier does not necessarily prove that it had no existence be- 

 fore ; as it is well known^ by those who have had experience 

 with the telescope, that one may look for a long while at a ce- 

 lestial object, and miss perceiving what he will readily see when 

 once he is told where to look, and what to look for. Seeing 

 what is new and unsuspected is quite different from seeing what 

 has been observed before. 



Though no noticeable changes in the position of the dark an- 

 gular forms could be observed in the course of two or three 

 hours, it does not follow that the system of rings does not rotate 

 upon an axis, as theory indicates ; since the supposed indenta- 

 tions seen on the ansae would be placed in the most unfavorable 

 positions for showing their motion, if they have any, because it 

 would be accomplished almost in a line with the visual ray, 

 either approaching or receding from the observer. 



Next to this division, but much less conspicuous, and to be 

 seen only on very good nights, is a narrow, grayish, and some- 

 what diffused line, called "the pencil line," shown at 6, fig. 1- 

 I have never been able to trace this line all around the planet, 

 as it diminishes very rapidly with the foreshortening, and is 

 soon lost. Probably I have never traced it more than 30° or 

 40° on each side of the major axis of the rings. The pencil line 

 has never appeared to me black and well defined, but rather 

 grayish and diffused. Sometimes I have had the impression 

 that it was irregular in width and in depth of tint. 



These two lines are the only ones I have observed, which 

 could, with a certain amount of probability, be said to be a sep- 

 aration of the rings ; though they might just as well be depres- 

 sions, or dark belts, especially the outer one. But the fact that 

 they have been observed on both surfaces north and south, ap- 

 parently corresponding in position, is in favor of their bemg 

 real separations of the rings. Though I have repeatedly endeav_ 

 ored to see the planet through the principal division between d 

 and e, fig. 1, I have never seen the faintest traces of it ; and I 

 am not aware that others have been more successful. 



K the principal division of the rings is, in fact, what it is said 

 to be, — viz : a space free from matter, and entirely disconnect- 

 ing the rings B and C,—l do not see why the planet has never 

 been seen through it. If the planet could be seen through that 

 space, the dark line forming the principal division would be m- 



