ON MAPPING THE SURFACE OF THE MOON. 4] 
Subzone No. 4. Lat. 7° to 9°S. Area IV As 13, 3, 44, 54, 62, 72, 82, 92, 
134, 144, 154, 184, 194, 21, 
22, 43?, 44, 45, 483, 61, 71, 
77, 95, 1072, 1152, 121. 
Subzone No. 6. Lat. 9° to 10° 8. Area IV AS 34, 50, 51, 53, 122. 
The lunar objects to which the above designating numbers in each area are 
appended have been examined since the construction of the maps of the areas, 
and may be regarded as testifying to the character of each object as it ex- 
isted at the time of examination, which in most cases agree with the descrip- 
tion in the catalogue. 
TII.—LINNE. 
Observations of this object continue to be made by gentlemen in concert 
with the Committee. In the last Report (Report, 1867, pp. 3 to 24) three 
essential features were described, viz. a large shallow crater, containing 
within it a small crater, both being replaced by a large ill-defined white 
spot under an increase of solar altitude. On the 26th of June 1868 Linné 
was observed under very favourable circumstances by Messrs. Huggins, Pen- 
rose, Birt, Webb, Carpenter, Joynson, and Williams, from 8.30 to 11.30 
G.M.T. During the earlier observations nothing was seen but a small cone, 
which cast a shadow to the east. This cone was not situated upon a ridge, 
the sixth of Schroter, as he states his spot v to be (see post, p. 44, and 
Report, 1867, p. 4), but appeared as if isolated, standing upon a slightly 
raised portion of the Mare Serenitatis, having Schroter’s sixth ridge to the 
south, the cone being in the line of prolongation of this ridge to the north. 
On the west a curvilinear ridge of lower altitude (given by Beer and Midler 
was seen, from the east foot of which the surface rose very slightly to the 
base of the cone. There was not the slightest indication of a shallow crater, 
nor was there the least appearance in the surface around the cone which 
might be considered indicative of its becoming a white spot, as the sun rose 
above it. The terminator was a little east of the cone, and the next ridge 
beyond the cone towards the east was becoming visible. 
Mr. Carpenter was the only observer who saw on the cone the crater- 
opening. From the drawings and descriptions of this object, it would appear 
to be very similar to a terrestrial volcanic cone, the eastern side being broken 
down. Messrs. Joynson and Williams record the cone as “a bright point,” 
an appearance it would present in telescopes of smaller aperture than those 
in which it was seen as a cone with crater-opening. 
During the earlier period of the observations the altitude of the sun was 
less than 1°, but as it became higher a change was observed, which will be 
described presently. The great importance of determining the true nature 
of this change is obvious. Was it actual, or was it optical? So far as the 
observations from 1866 (Oct. 16) to 1868 (Sept. 7) testify, this change takes 
place, more or less constantly, with /ow solar altitudes (see post, p. 45, points 
of contrast 7th and 8th). It is consequently of importance to ascertain by 
future observation whether the transition from the visibility of the lunar 
surface to that of a white spot, by orin which the character of the surface 
is no longer rendered apparent, is constant for solar altitudes and azi- 
muths of the same value. If the change be purely optical and dependent 
upon the two conditions following, viz. the nature of the lunar surface on 
the one hand, and the incidence of the solar rays on the other, as soon as 
the sun attains the requisite altitude and azimuth, the altered appearance 
1868. E 
