20 REPORT— 1868. 
interior as 1: 1°75 (see fig 3), breadth of shadow 1°61 +, illuminated inte- 
rior 2"-89+. 
*13(x). A mountain-range forming the N.W. portion of the boundary of the 
partly enclosed plain IV A®? IV AY 3; it is gently curved. Its W. por- 
tion is IV A’1!. The central part is hollowed interiorly ; length 13": rer 
breadth of base, the E. part, 7!:18, the central part 6"-71, the W. part 6”: 71. 
Pe la(x): The northern of three very conspicuous cr aters, W. of Hipparchus, 
which are seen under every variety of eater ne the second in order on 
area IV Af, 11”-19, mag. 0°66, E of B. & M. 7° of brightness, G of Lohr- 
mann, Sec. a, 8° of brightness. Position eae order x 14, b 
-0138 W.S.W. of photogram. It is N.W. of Horrov, and Fig. + 
has a small shallow crater, IV A* }, adjoining it on the S.E. A 
It is situated very nearly on the border of the high land form- Y 
ing the W. border of Hipparchus. It appears from the pho- Wow 
togram to be very deep. With a morning terminator ad- 
vanced beyond Copernicus, long. 21° E., the interior shadow of the W. rim 
is still gibbous, the E. interior sloping upwards from it tothe E.rim. At 
this stage of illumination the proportion of shadow to illuminated interior 
is as 1: 1-667 (see fig. 4). Breadth of shadow 4':20, of illuminated inte- 
rior 6-99. 
15(x). A small shallow crater adjoining ITV A* ! on the 8.E., the sixth 
in order upon area IV A*. It is shown by B. & M. and Lohrmann. 
Longest diameter 6:25, shortest 5°31, mag. 0°32. It is situated on the 
very border of the high land W. of Hipparchus, and on the “ fault” TV A” 12 
TVA B20 TH ASE. 
**16(x). Horrox’.—The largest crater on area TV A’. It is marked 6 on 
B &M.’smap, 232 on Lohrmann’s, and F on Lohrmann’s Sec. I. Position second 
order x 16, :0204 W. of [LV A®” on photogram. Longest diameter E. by N.- 
W. by 8. (nearly) 19”:67, shortest N. by W.-S. by E. 17-43, mag. 1:17. 
B. & M. record a brightness of 3° for the interior, and 5° for the border, 
when seen under favourable circumstances. Lohrmann’s value is from 4° to 
5°. Its form consists of a semiellipse on the east side, and two nearly rec- 
tilineal walls on the W., which are inclined to each other at an obtuse angle. 
It has a low central hill, [V Af 7, but not a very level floor, on which are 
two hillocks, IV Af? and IV Af 24, The interior is probably bowl-shaped. 
The E. interior slope rises from this floor, and with a morning terminator 
advanced beyond Copernicus is brightly illuminated; the KE. y,, 5 
boundary of the shadow of the W. border is nearly rectilinear. a 
Proportion at this stage:—shadow to illuminated portion as 
1:1-509 (see fig. 5); breadth of shadow 7’':84, of illuminated 
interior 11:83. There are two ridges on the interior W. slope. ‘3 
Horrox appears as an isolated crater on the lower level of the N.W. part of Hip- 
parchus. The space between the N.W. wall of Horrow and the fault TV A” ! 
TV A#20 TV A*? is mentioned by Lohrmann as a narrow valley (Topographie 
der sichtbaren Mondoberfliche, sec. i. p. 50). This appears to be the mouth 
of the valley IV A* #! IV A* 7, in which is the depression IV AF 78, 
17. Hieparcuvus?.—Lohrmann’s Map 233. The north-western part. Jhis 
formation is described in the letterpress to areas IV A*, IV AS, pp. 12, 138, 
and in the Report of the Brit. Assoc. 1866, pp. 248, 249. As itis only seen 
a Named in commemoration of Mr. Horrox, who computed and observed the transit of 
Venus in the year 1639. 
> Named by Riccioli in commemoration of Hipparchus, who compiled the first catalogue 
of the fixed stars in the second century before our era. 
ae 
