ON MAPPING THE SURFACE OF THE MOON. 29 
This spot should be assiduously watched. The spot IV A¢*° TV A*17, de- 
scribed in letterpress to areas [TV A*, IV AS, pp. 15 and 26, and Report 
Brit. Assoc. 1866, pp: 251 and 262, as a bright spot, has been seen by the 
author and by the Rey. W. O. Williams as a crater—on one occasion (Oct. 18, 
1867) by Mr. Williams conspicuously so with a central cone casting a shadow. 
In the December lunation Mr. Williams was unable to detect any trace of 
a crater; but on January 3, 1868, the succeeding lunation, Mr. Baxendell saw 
it as a shallow crater about ? of the diameter of IV A*’. Mr. Williams has 
steadily continued his observations on this spot, from 1867, Oct. 7, to 1868, 
May 7, which I have arranged in the order of the sun’s altitude above it ; 
and as this arrangement illustrates the use of the Table on pp. 10, 11, it may 
be well to introduce it here, both as an example of referring observations to 
solar altitudes, and also as indicative of the changes of appearance dependent 
on the angle of illumination. 
OssEryations or TV A*!7 [VA$3; Larrrupe 5° §., LonerrupE 2° Wrst. 
Morning Illumination. 
Autho- | ©’s |Bright- 
No. Date. G.M.T. : Character. 
rity. alt. ness, 
1. |1867,May 11. | 83 | Birt 6-6 | ...2.. | A shallow crater. 
2. | 1868, Feb. 1. 5-6 | Williams| 6-12) ...... Crater well seen. 
3. | 1868, Mar. 31. 7k Birt 62121) Si. ee Crater well defined. 
4. | 1868, Jan. 3. 5-6 Williams | 12-18} ...... Discerned central cone,not certain. 
5. | 1868, Jan. 3. Baxendell| 12-18 | ...... Well-marked shallow erater. 
6. | 1867, Nov. 5. 9-10 | Williams | 18-24) 7 | Very bright, streak of interior sha- 
dow on the west. 
7. | 1868, April 1. 5-G | Williams | 18-24 4 | Whitish patch of light. 
8. | 1867, Dec. 5. 6-8 | Williams | 24-30 5 | Whitish spot; no crater. 
9. | 1868, May 1. 10-11 | Williams | 24-30} ...... | Whitish patch, line of interior sha- 
dow on the west. 
10, | 1867, Oct. 7. 83-10 | Williams | 24-30} ...... A very bright spot. 
11. | 1867, Nov. 6. 8-10 | Williams 30-386; 6 | A bright patch of light; streak of 
shadow scarcely discernible, 
12. | 1868, April 2. 5-6 | Williams | 30-36) 4 Whitish patch of light. 
4 
13. | 1868, April 2. 8h Birt 30-36 Very shallow crater with interior 
shadow. 
14. | 1867, Dec. 6. 9-10 | Williams | 36-42 5 Whitish spot ; no crater. 
15. | 1868, May 2. 63-10 | Williams | 36-42) ...... Long patch of light to east. 
16. | 1868, May 4. | 103-112) Williams | 48-54! ...... Two bright spots. 
17. | 1868, May 5. | 103-113) Williams | 60-66) ...... Two bright spots nearly equal and 
circular. 
18. | 1868, May 6. | 93-102 | Birt 72-78| 65 | Two bright spots. 
19. | 1868, May 7. | 113-12 | Williams | 83-€5) ...... Two bright spots; E. spot largest. 
; Evening Illumination. 
20. | 1867, Nov. 15 | 18-20 | Williams | 36-30; 10 | Very bright. 
21. | 1868, Feb. 12. 204 | Williams | 30-24| 6,4 | Crater very conspicuous; with east 
peak very bright; 6°. 
22. | 1867, Oct. 17. | 13-15 | Williams | 30-24 ...... Crater very conspicuous. 
23. | 1867, Oct. 17. 132 | Ingall 30-24] ...... Drawn as a crater. 
24. | 1867, Oct. 18. | 17-19 | Williams | 18-12} ...... Crater very conspicuous; small 
central cone casting ashadow. 
25. | 1868, Jan. 15. 201 | Williams }12- 6] ....... | The crater conspicuous, with inte- 
rior shadow on east, fully 
equal to that of IV A*’. 
