Fig. 2. 



Tin' MUOII. revolving round the Ecutli and accompanvina it i/i 

 ^ its a?mual revolution round the Sun . describes a. peculiar 

 in the heavens termed OIL Epicvcloid -.Tliis curve is 

 formed of 22 arcs and one third nearly fa^.Z. A f .let the 

 ?arth. 1. advance an 8** part of 3O degrees to \.thc Moon, 

 whldi was at first at L. will have described round t/ie 

 Eaj-th the arc ii.S. or. an S^part of a tiination,& at the \ 

 same time accornparivina the Earth in its progress, will 1 

 have traced in the heavens the portion of 'the Epicycloid, 

 L.S . It is b}' a combination of t/ie movements previous- 

 ly noticed that tlie Moons phases or. the various aspects 

 under which she is seen from the Earai.are caused . The 

 central figure illustrates these changes of the Moons 

 appearance - thus , when in conjunction, i.e. between the 

 ^ un and t/ie Earth . she is not visible because her dark 

 side is turned towards us and she reaches the merid 

 -ion at noon.it is then New Moon rather less than four 

 days after, the Moon.which has reached the meridian 

 or an hour later each dav , is perceived as a slender 

 crescent with its points towards the east.sheis then45r. 

 distant fi-om the point of conjunction, at her first Oc- 

 tant when otdy a fourth part of her illuminated surface 

 is seen fiom the Earth as marked at BLO. she then reach- 

 es ttie meridian at 3 o'clock in me afternoon . Arrived 

 at 90? 'die point of conjiuiction. hob: of her disk is visible, 

 she is then said to be in her first quarter < reaches the 

 nuridian atGinthe ei'enina. At I35?is her second Octant 

 'hen 3 j of her disk are visible, she men reaches the mer- 

 idian at fl in the ei'enina. At 180? from the first point in 

 her orbit, she willbe again on the same line, in opposition 

 with the Sjin.& will present to the Earth the whole of her ill 

 ' undnated disk.rcachuu) the meridian at midniaht it is then 

 f ..^^^'^^ from this point inher o?-bit theMoon bea- 



-ins to wane A three or four days after at 225? is in her third Oc- 

 t. reaching the meridian at 3 in tttc morninci & turnina towards 

 the Earth % or her disk as in her second Octatit. thus erhibitina in 

 her decline appearances analogous to those in the earucr part of 

 her revolution . The two points in the Moons orbit where she is in 

 /* opposition or in conjunction with the Sun are named- Svzvgi 

 //those where she is iiiher first and last c/uarters - Quadratures . 



Drawn A Engraved byl.Ilower.FemoiiiaLU' Londi 



