26 ‘ REPURT—1868. 
Area LV A&. 
58.| IV A®16 ..| Horrox.—The most conspicuous 
crater on Terra Astronomica, 
TA Fes 1517 9 seh. ae aa B. & M.b. | L.F.| Ph. 
The initials B. & M. signify that the crater is to be found in Beer and 
Miidler’s Map, L. in Lohrmann’s Sections, and Ph. on De La Rue’s and 
Rutherford’s Photograms. 
18(x). A depression W. of Horrow and the W. border of Hipparchus, nearly 
midway between LV Af 14 and IV Af 19%, It is very irregular in form, and 
filled with a mountain-mass which gradually ascends from the W. and N. to 
the very border of Hipparchus. This mountain-mass rises from the W. foot 
of IV Af 18, and culminates in the peak IV A* *5, which is the highest point 
in the W. border of Hipparchus. It has upon it a white spot, IV A* *7, just 
where the rise commences towards Hipparchus. This spot is probably the 
small crater given by B. & M. and Lohrmann*, It presents an appearance 
analogous to that of Zinné, both on the photogram and as seen in 1867, and 
should be watched attentively from time to time. It spreads gradually from 
a bright centre, and degrades in brilliancy as the valley at the foot of the 
mountain-mass is approached. The brightness of IV A& #7 scarcely equals 
that of Zinné on Rutherford’s photogram, 1865, March 6. 
A mountain-crest crosses [TV A* 18 from N.W. to 8.E., the N.E. side being 
filled with the mountain-mass IV Af 47, which also culminates on the border 
of Hipparchus. Between TV A**8 and IV A 47 is an inlet, [V A* 45, in the 
mountain-border facing the plain W. of Horrow. IV A*®!§ appears as a 
somewhat large bright spot in full moon, but is not a very conspicuous object 
at other times. 
**19(x). The middle of three very conspicuous craters W. of Hipparchus(see 
TV Af 14), Itis G of B. & M., who record it as of 7° of brightness, and E 
of Lohrmann’s Sec. I. It is the third crater in order upon area IV A®. Its 
longest diameter measures 9'-42, and shortest 8-48, mag. 0°53. This crater 
is very deep, and has a small crater, [V A®*!, adjoining it on the Fig. 7. 
N.E. It is situated on the sloping edge of the high land W. of 
Hipparchus, ard in the angle formed by the intersection of 
the fault IV A” TV A&2%0 TV A’? with the fault TV A’? 
IV Af & (see letterpress to azeas IV A*, IV AS, pp. 19, 20, 
and Report Brit. Assoc. 1866, pp. 255, 256). With a morning 
terminator advanced beyoad Copernicus, the interior shadow of the W. rim is 
decidedly gibbous (see fig. 7), the E. interior sloping upwards from it to the 
E. rim. Breadth of shacow at this stage of illumination 3-78, of illuminated 
interior 4°71. The proportion of shadow to illuminated interior of the 
E. slope is as 1: 1:25. This is not so small as the proportion of shadow to 
the bright interior of the crater IV Af; and this, with the shadow of 
IV Af !9 being more gibbous than that of IV A’ 4, indicates that IV A*! is 
the deeper crater. Po: 
The form of IV Af departs very considerably from that of a circle ; the 
2 1868, May 149» 45m G.M.T., it was seen with the Crossley equatorial, 7-3-in. aper- 
ture, most unmistakeably as a crater with gibbous interior shadow of about ‘33 of the dia- 
meter. On May 24 7h 25™ G.M.T., it exhibited some approximation to the class of“ light- 
centres.” See Brit. Assoc, Report, 1866, p. 218. : 
