36] NOTE ON WILLIAM BALL'S OBSERVATIONS OF SATURN. 283 



1656, et alias adscriptum invenio, lineam obscuram fuisse evidentissimam, ec- 

 nempe positu, qui pag. 545 System. Saturnii memoratur." Pp. 624, 625. 



"Non segre nunc fidem habitum iri spero, turn mihi turn Anglis simul 

 observatoribus, qui anno 1657 oblonga Saturni brachia disco utrinque con- 

 juncta spectavimus, qualia exhibet figura Systematic mei pag. 545, quain hie 

 repono; non autem binorum orbiculorum forma a medio disco disjunctorum, 

 ut Eustacius se ilia eodem tempore vidisse dejerat. Adderem hie schema 

 quod mihi a D. Ball, supra memorato, advenit, nisi plane simile esset huic 

 nostro, hoc uno tantillum duntaxat abludens, quod brachia ilia ubique paulo 

 crassiora ille referat. 



"Earn vero formam a 5 Nov. 1656 ad 9 Jul. 1657 sibi apparuisse 

 scribit. Apertis autem brachiis, qualis pag. 547 Systematis mei et hie repre- 

 sentatur, talem a 9 Nov. 1657 ad 7 Jun. 1658, idem observator depingit, 

 simillima prorsus figura, nisi quod ad positum zonae obscurae attinet, de quo 

 dixi supra. Ac denique a 3 Jan. 1659 ad 17 Jun. ejusdem anni, ansis 

 paulo latius adhuc apertis. Et hsec quidem ille, ignarus adhuc mese hypo- 

 theseos, ne ob pra3conceptam opinionem aliquid indulsisse sibi existimetur. 

 Neque ego aliter quam se revera habent referre auderem, cum redarguere 

 me, si fallam, autori observationum in promptu sit." P. 626. 



The following extract comprises all that is material in the Paper in 

 the Philosophical Transactions : 



"This observation was made by Mr William Ball, accompanied by his 

 brother, Dr Ball, October 13, 1665 at six of the Clock, at Mainhead [Mamhead] 

 near Exeter in Devonshire, with a very good Telescope near 38 foot long, 

 and a double Eye-glass as the observer himself takes notice, adding, that 

 he never saw that planet more distinct. The observation is represented by 

 Fig. 3 concerning which, the Author saith in his letter to a friend, as 

 follows, This appear'd to me the present figure of Saturn, somewhat other- 

 wise, than I expected, thinking it would have been decreasing, but I found 

 it full as ever, and a little hollow above and below. Whereupon the 

 Person, to whom notice was sent hereof, examining this shape, hath by 

 letters desired the worthy Author of the System of this Planet, that he 

 would now attentively consider the present Figure of his Anses, or Ring, 

 to see whether the appearance be to him, as in this Figure, and conse- 

 quently whether he there meets with nothing that may make him think, 

 that it is not one body of a circular Figure, that embraces his Disk, but 

 two." 



362 



