2 REPORT—1868. 
that the superstructure may be characterized by accuracy and precision as 
well in recording detail as in discussing observations, and that the results 
arrived at may be beyond dispute and fully capable of testing any question 
that may arise as to the state of the moon’s surface. 
Reeistration oF Ossects.—During the past Association year, the regis- 
tration of objects has proceeded in conformity with the mode adopted in pre- 
vious years. The numbers are as follows :— 
553 on 128 areas In Quadrant ik 
a5B- 8 86 33 IL. 
Pats sha 57 33 | ae 
642, 62 ss IV. 
Total ....-1763 333 
Ovuttine Mar.—The drawing of area IV Af has been prepared, engraved, 
and a number printed for distribution ; also a catalogue of 99 objects upon 
this area has been compiled and printed. Several corrections and additions 
to areas IV A* and IV A¢ have been made; so that the number of objects in- 
serted on the maps, either engraved or in MS., and included in the Catalogue, 
amounts to 337, which is a trifle less than 1+ of the number inserted in the 
folio registers. 
In preparing the catalogue, every care has been taken to meet the growing 
requirements of selenographical research. The doubts that surround the 
labours of earlier selenographers, as to correctness of details, many delinea- 
tions being conventional rather than actual, combined with the absence of 
precision in describing lunar features, render it essential that the description 
of an object should, if possible, embody its principal characteristics at a given 
epoch. The compilation of the catalogue was commenced with this view ; and 
it has been steadily maintained in the portion accompanying this Report as 
well in the previous ones, each description being as much as possible equiva- 
lent to a trustworthy observation. 
As the positions of objects on the outline map are for mean libration, it 
may be well to mention that the moon attains a state of mean libration 
(nearly) in 1868 on October 244 20" 8™. 
Resvtts or Osservations.—More than thirty-two gentlemen have under- 
taken the examination of special zones or particular objects. The work 
accomplished in accordance with the instructions in the letterpress of IV A*, 
TV AS is as follows :—106 objects in the three areas have been independently 
identified, 7. ¢. originally laid down from De La Rue’s and Rutherford’s pho- 
tograms, or from observations made by the Secretary; they have been reob- 
served by gentlemen in whose zones they occur. In seven cases the obser- 
vations were made by four independent observers, in six cases they 
were made by thrce independent observers, in 32 cases by two, and in 61 
by one observer only. Appendix II. contains the Association symbols of 
these objects, with such notes as may be deemed necessary, also the addi- 
tions to the map and catalogue. See post, pp. 40 and 41. ; 
Observations of this kind may be greatly facilitated by choosing “ test 
objects” in accordance with the suggestion of Mr. Slack, who recommends 
“ Crater-Row ” (IV A$28, TV As 14, TV AS 5, TV AS 18, TV AS 1°, five eraterlets) 
as very suitable for area IV A‘. If the craterlets, especially IV A$ 18 and 
TV A$ 19, come out sharply and well defined, and can be seen distinctly and 
without tremor, the earth’s atmosphere is in a good state for observation ; and 
if, at the same time, neighbouring objects are indistinct, hazy, and ill-defined 
(phenomena that may be occasionally noticed), then it would appear that this 
