ON MAPPING THE SURFACE OF THE MOON. 7 
APPENDICES. 
I.— BRITISH ASSOCIATION OUTLINE? MAP OF THE MOON, 
Zone II., Anza IV Af. (See Plate I.) 
Preliminary Remarks. 
Tue principles upon which the map is constructed and the catalogue compiled, 
with the materials employed for these purposes, have been already mentioned 
in the Report presented at Nottingham in 1866. Instructions for observing 
the objects and correcting the detail will be found in the letterpress accom- 
panying the areas IV A* and IVY A¢. In preparing IV A for engraving and 
printing, a few additional notices have become requisite. In addition to the 
symbols for indicating certain objects on the maps, inserted on p. 4 of letter- 
press to areas IV A“, IV AS, and Report Brit. Assoc. 1866, p. 240, three 
others may be found useful; so that the revised code of symbols will be as 
follows :— 
Points of the first order. 
Points of the second order. 
Bright spots. 
Craters. 
Rings. 
Depressions. 
Mountains. 
Valleys. 
Mountain-slopes and valley-sides. 
Clefts. 
Very conspicuous objects. 
Easy objects. 
Difficult objects. 
Objects rarely visible. 
. Beer and Miidler. 
Lohrmann’s Sections. 
Lohrmann’s Map. 
Schmidt’s Rills. 
. English feet. 
Metres. 
Of the photograms employed, De La Rue’s, being so near the epoch of mean 
libration (Report Brit. Assoc. 1866, p. 215), is used for the determination of 
positions, while Rutherford’s is the most suitable for the measurement of 
the extents and distances of objects. The elements of this photogram are as 
under :— 
Epoch 1865, March 6. 
= 
is directed towards 
the lowest point. 
l=—e > (Ooc- 
N.B. The arrow ans 
* 
* 
Map x 
= 
& 
OF is a ee 
ah iol 
For illumination :—Longitude of terminator = 2 
Inclination of terminator to meridian = 
North pole enlightened. 
a This map is not intended to be a perfect or complete Lunar Map, but only a guide to 
observers in obtaining data for the construction ofa complete map. 
Ho 
6-1 E. 
6-6 
