VOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. 733 



Stance, will undoubtedly throw some light on the situation and excentricity of 

 their orbits; as it will be found, that the calculated places of these conjunctions 

 require elliptical motions to bring the satellites to such appearances, which, in 

 circular orbits, could not so accurately have taken place. Nor can we ascribe 

 the disagreements to the fault of the observations, since a very few minutes will 

 suffice to determine the time of a conjunction, which never lasts long. For this 

 reason also, he carefully avoided deducing the epochae) from conjunctions, even 

 with the 6th satellite, which moves so rapidly, that at first sight we might think 

 those situations favourable. 



The mean motion of the 5 old satellites being sufficiently accurate for the 

 present purpose. Dr. H. has taken from the above-mentioned tables of De la 

 Lande; but those of the 6th and 7th, of course, are the result of his own ob- 

 servations. The geocentric place of Saturn, whose complement is to be added, 

 in order to reduce the Saturnicentric situation of the satellites to the apparent 

 one, he has taken from the nautical almanac to the nearest minute; and, as he 

 had always confined himself to a literal transcription of the observations from 

 the original journal, all the memorandums which are necessary either to explain 

 them, or to correct mistakes in the names of the satellites, are thrown into 

 notes, that there may be no interruption in the succession of the observations. 

 Dr. H. then gives a long series of the observations of all the satellites, as copied 

 from his original journal, with all the minute particulars, of course not necessary 

 to be re-printed here. 



Dr. H. then resumes his discourse. From the observations on the 7 satellites 

 of Saturn above-mentioned, and closely compared with their calculated places, it 

 appears evidently that the revolutions of these satellites are so well ascertained, 

 that we may, without hesitation, determine that no phenomenon on the ring of 

 Saturn, in the shape of lucid spot, protuberant point, or latent satellite, can be 

 occasioned by any of them, when, on computation, we find that the place of 

 the satellite differs from that where such appearances were observed. In con- 

 sequence of this deduction, he found that the observations could not be explained 

 by any of the known satellites; it remained therefore to be examined, to what 

 cause to ascribe the appearance of such lucid spots. 



The first idea that occurred was that of another satellite, still closer to the 

 ring than the 7th; and if a revolution, slower than about 15 hours and a quar- 

 ter, could have been found, which would have taken in the most material places 

 in which bright spots were seen, he should have continued of opinion that an 

 8th satellite, exterior to the ring, did exist, notwithstanding more observations 

 had been wanting to put the matter out of all doubt. But this being impracti- 

 cable, he examined, in the next place, what would be the result if these sup- 

 posed satellites, or protuberant points, were attached to the plane or edge of 

 the ring. 



