330 PHILOSOPHICAL TRANSACTIONS. [aNNOI/IS. 



observations which clear up the point, and by showing the errors of those first 

 tables, has made us certain that we have seen the whole satellitum of Saturn 

 ourselves. Other observations of these satellites are in the Memoirs for J715. 



Having by the help of these late observations corrected the motions of the 

 satellites, which it was not possible for their first discoverer to settle truly, in 

 the short interval before 1687; and having fixed their epochs for the present 

 year, we were enabled to know where to expect them with more certainty, and 

 to distinguish them from one another, and from the small fixed stars appearing 

 with them. And Mr. James Pound having, by means of his steeple of Wan- 

 sted, provided a gnomon high enough for the purpose, and having fitted a very 

 commodious apparatus for using the Society's said long telescope, soon disco- 

 vered by it all these five satellites; and lately communicated the following very 

 curious observations. 



1718, April 21^ 10'' 40"^, the 3d and 4th satellites of Saturn were in Apogseo, 

 a little post their conjunction with Saturn, a perpendicular from the 4th to the 

 transverse axis of the ring, or line of the Ansae, fell a little without the eastern 

 Ansa; and a line through the 4th and 3d touched the eastern limb of Saturn. 



The first was northward of the line of the Ansae, and therefore in the Apo- 

 gason semicircle also, distant from the said line about as far as the end of the 

 conjugate axis of the ring was from the centre of Tp, viz. nearly -f- of Saturn's 

 semidiameter ; and it was about a semidiameter of the ring from the western 

 Ansa. 



The second was a very little southward of the line of the Ansae, and there- 

 fore in the Perigaeon semicircle, above a semidiameter of the ring, or about the 

 semidiameter of the ring -f- the semidiameter of Tp, from the western Ansa. 

 And the third, first, and second, were in a straight line. 



At 10^ SO'" a perpendicular from the 3d to the line of the Ansae, fell almost 

 on the middle of the bright part of the eastern Ansa, but somewhat nearer the 

 centre than the said middle. 



April 22^ 1 1'^ 5"", the four innermost satellites were all eastward of h). The 

 second and fourth in the Apogaeon, and the first and third in the Perigaeon 

 semicircle. A line through the second and fourth touched the south-east limb 

 of Tp, A line passing through the third, and the end of the conjugate axis of 

 the ring, was parallel to the line of the Ansae. 



At 1 1*' 10*", a perpendicular from the first to the line of the Ansae, fell on 

 the eastern extremity of the ring. 



These distances and directions were taken only by estimation, and not by any 

 actual measurement. The fifth, or outermost, satellite being at this time near 

 its greatest elongation eastwards, among several very small telescopic stars, he 



