232 REPORT— 1866. 



Addenda to Appendix I. 



Beer and Madler, with the view of determining the position of the north- 

 pole of the moon, ascertained by measures of the First Order, direct and 

 differential, the latitudes and longitudes of the following points (all moun- 

 tains): — Euctcmon c and I, Gioja y, three with high northern latitudes and 

 ~ west longitudes considerably exceeding 90°, Anaxagoras i within 5° of the 

 pole and 108° east longitude, and Gioja a within 2° of the pole and 7° east 

 longitude ; the last comes within the orthographical projection mean libra- 

 tion, the others are not visible in mean libration. The drawing of these and 

 neighbouring points (without the parallel and decUnatiou- circles) forms 

 Table I. of Beer and Miidler's ' Beitriige zur physischen Kenntniss der himm- 

 lischen Kor2)er im Sonnensysteme.' The observations and results are recorded 

 on pp. 6G and 67. The best time for comparing the drawing with the moon is 

 when she has high south latitude. 



Lat. Long. 



Euctemon e 78 1 46 N. 126 37 35 W. 



Euctemon Z 83 16 27 N. 118 40 W. 



Gioja y 86 44 33 N. 174 46 33 AV. 



Anaxagoras i 85 24 N. 108 14 35 E. 



Giojaa 88 4 41 N. 7 2 9 E. 



Appendix II. — Deteemhtation op Points op the Eiest Oedeb. 

 Explanation of Terms used in this Appendix, 



LiBRATiox nr lATirrDE arises principally from the northern and southern 

 parts of the lunar globe coming alternately into view in consequence of the 

 inclination of the plane of the moon's orbit to that of the ecliptic. 



LiBKATioN IN lONGiTTJDE aiiscs from thc same hemisphere of the moon 

 being constantly directed, not towards the earth, but towards the other focus 

 of the elliptic orbit of the moon, in conseq.uence of which, while the moon 

 describes the perigean portion of her orbit, the first meridian, from which 

 all seleuographical longitudes are reckoned, is gradually transferred from 

 west to east. The same meridian is transferred from east to west during the 

 period that the moon describes the apogean part of her orbit. The same 

 hemisphere being directed always towards the other focus of the elliptic orbit, 

 is the result of the uniformity of the rotation of the moon on her axis. 



Geocentric latitude and longitude of the moon's centre is the latitude 

 and longitude of the moon's centre as seen from the earth's centre reckoned 

 from and on the ecliptic. 



Selenocenteic latitudes and longitudes are latitudes and longitudes of 

 points on the moon's surface as seen from the centre of the moon. Lati- 

 tudes are reckoned from the moon's equator, and longitudes are reckoned 

 071 the moon's equator from the point at which the moon's equator intersects 

 the ecliptic. This point, which is the ascending node of the moon's equator, 

 is rigorously identical with the descending node of thc moon's orbit. 



Belenogeaphical latitudes and longitudes are the latitudes and longi- 

 tudes of points of the moon's surface reckoned as on the earth's surface 

 from the equator of the moon and the fii-st meridian. See fig. 6, p. 228. 



General Principles. 



1. The great importance of augmenting the number of points of the first 

 order — for the purpose of mapping the surface of the moon on a large scale, 

 and more especially for drawing up monograms of special portions on a still 



