SECT. IX.

habendus est, neglecto videlicet ejus incremento vel decremento nonnullo, quod à Cometæ motu inæquabili in orbe proprio oriri possit. Distantia verò Cometæ ex hac parallaxi sic colligitur. Designet S Solem, acT Orbem magnum, a locum Terræ in observatione prima, c locum Terræ in observatione secunda, T locum Terræ in observatione ultima, & T lineam rectam versus principium Arietis ductam. Sumatur angulus a r i e s . p n g ) * T V * æ q u a l i s a n g u l o [ ! [ A r i e s ] ( h t t p s : / / c o d a l . c c / a p i / m e d i a / f i l e / 420 ) ] ( h t t p s : / / g u t e n b e r g . p g l a f . o r g / c a c h e / e p u b / 28233 / i m a g e s / aries.png" rel="noopener noreferrer nofollow"> QF , hoc est æqualis longitudini Cometæ ubi Terra versatur in T . Jungatur ac , & producatur ea ad g , ut sit ag ad ac ut AG ad AC , & erit g locus quem Terra tempore observationis ultimæ, motu in recta ac uniformiter continuato, attingeret. Ideoque si ducatur g a r i e s . p n g ) i p s i * T * [ ! [ A r i e s ] ( h t t p s : / / c o d a l . c c / a p i / m e d i a / f i l e / 420 ) ] ( h t t p s : / / g u t e n b e r g . p g l a f . o r g / c a c h e / e p u b / 28233 / i m a g e s / aries.png" rel="noopener noreferrer nofollow"> parallela, & capiatur angulus a r i e s . p n g ) * g V * a n g u l o [ ! [ A r i e s ] ( h t t p s : / / c o d a l . c c / a p i / m e d i a / f i l e / 420 ) ] ( h t t p s : / / g u t e n b e r g . p g l a f . o r g / c a c h e / e p u b / 28233 / i m a g e s / aries.png" rel="noopener noreferrer nofollow"> QG æqualis, erit hic angulus gV Page 476 æqualis longitudini Cometæ è loco g spectati; & angulus TVg parallaxis erit,