VISIBLE HEMISPHERE 



Of T//K 



D 



In urder tt> understand the phenomena e.rhibiJed bv the Jloa/i. 



the most <nrrrid and ticcwnff observation or'n-cn- part of tJie 



lunar disk is required '.at all the various periods of her Hbru 



twn .The position of remarkable spots must be detaminetl 



with the most ryoiuvus ejxictittide . as it is round, from 



the i-hanae of situation relative to snrrowuiinn appear 



Y#OV. consequent uf>on the Jfwris phases, that, a spot 



i-lenrlv distinguishable bt the naketi eye upon hersw 



face, when at the ridl. /// be with diftiadh' disnmed 



iien b\ the alas.* towards the last quarter . 



Thf iippftimnccs obsen-iil on the Moons surface are 



t-ansed. either l>\ difference of let'cl.or PV differ 



encr of the intensity of the liaht . The lif/ht ret 



lected mm the sun'ace of the Moon is plainly 



fi-n tr> be of different shades: although the tiaht 



fr parts are generally the niountains.it the dark 



er ones the low plains . still.airtrid obscn-aaon.' 



have shown that this ijt not iilwqvs the case. 



but that, the streaks or 'light. whicii at the full 



surpass in bri/liann all the adjacent parts, some 



-times e.rist entirely independent of mountains. 



and extend alike over heights and valleys with 



out beina affettetl bv them . Besides differmce 



in intensiti- or' the light, colours specirit-aUy differ 



ait may be observed. particularly gnvn .sometimes 



ii colour of a redilish tint. at others a yellowish brown. 



The derations ofthelfoon are in fieneral or' a much 



more />recif>itoiis nature than those of the eajfh.ln the 



plate, the edges of the steeper craters, more especially 



those or'small e.i-tent.aretjeneralh' shown b\' a plain iint- 



the narrow dais orrwines bv paralel lines without a cross 



tint . The middle edge or' thf Noon. i.e. the great circle which 



in the mean lilavtion seperates the hemisphere which is visible 



rrorn that whicii is invisible is iiivesmirilv delineated in ruiaile. 



Chains of miHintains. or mountainous regions of any importain-i: 



namfti after the inoiaitams of the mrth.and the various spots after 



d/stiniiitishfil men. on unne.n'd . To avoid confusina the objects in the 



plate bv a profusion of figures . the Moon's surface is divided into ft 



parts, the numbering of tlie spvt.t in eacJi (vmmeniina with unit . 



S < A L K 



