Difappearance of Saturn's Ring in tbe Year 1803. 221 



northern fide of it, which is turned from the fun. The ring 

 then, tor the firlt time, becomes to us invifible: but this 

 invifibihty is not of long continuance ; for, as may be feeii 

 by the figure, the earth on the i(l of January, by its Satur- 

 Uioceatric apparent reircgrade motion, pafles a fecond time 

 through the plane of the ring, and goes to the fouth- 

 ern or illuminated fide, and the ring then begins 10 apj:>ear 

 again as a Itraight line. In February, March, and April, 

 the earth recedes more and more from the plane, and the 

 ring becomes broader and more perceptible. But the fun 

 during thefe months approaches nearer to the plane of the 

 ring, and by thefe means it is illuminated in a more oblique 

 direAion. In the month of May the earth is at its greateft 

 dirtance from the plane of the ring, while the fun approaches 

 it more and more till the middle of June, when lie palTes 

 through the plane in e, and the ring for the fecond time be- 

 comes totally invifible to the earth, which is then on its dark 

 fide. From this period, during the month of July and till 

 Auguft, the ring will remain in this ftate. About the 18th 

 of Auguft the earth will pafs, for the third lime, through the 

 plane of the ring, as it will then be on the northern, which 

 is now the illuminated fide of the ring: it will a^ain appear 

 as a ftraight line, and be vifible when viewed through oood 

 telefcopes : it will increafc in li'j,ht and breadth in September 

 and Odober in proix)rtion as the earth and the fun recede 

 trom the plane. 



Between the+ft of November t8g2 and the iftofOftober 

 1803 the ring of Saturn twice difappears and twice reappears. 

 At the firlt difappearance on the 13th of December 1802, 

 Saturn in the morning will be in the eaftern part of the hea- 

 vens; and the firfi; reappearance will be about the yih of 

 January 1803 '■> Saturn in the night-time being on the lame 

 fide of the heavens. 



At the fecond difappearance in the middle of June, Saturn 

 in the night will be in the wtft, and, as he fets half an hour 

 after midnight, the pha^nomenon may be obfervcd. But at 

 the fecond anil laft difappearance in Auguft, Saturn will be 

 after the I'un, and therefore the phaiuomenon cannot be feen.^ 

 in the month of 0(itol)cr, when Saturn emerges from the 

 i'un's rays, he mav be fecn before fun-rife in the eaft, and 

 the ring then will be very vifible. 



li\ regard to the a!)Ove calculation of the times of the dif- 

 appearance and rcapjiearance of Saturn's ring, the accuracy 

 of them, and the correfpondenre of them with the phreno- 

 niena, mutt dci)end on the acctiracv of the tables and the 

 theory hitherto adopted in regard to the pofitiou oi the ring, 

 y The 



