OBSERVATIONS OF LUNAR OBJECTS, 281 



crossing the east arm of the trident, terminates about halfway between the 

 hitter and the west limit of the sector. During the May and June lunations 

 I had faint glimpses of it, but it was then a more difficixlt object than it 

 is now." 



1870, September 6. — Mr. Gledhill recorded the floor as dark, =0-66. 

 Streaks very bright and well seen. 



1869, jS'ovcmber 15. — Mr. Pratt has the following remarks on the light- 

 streaks: — " The trident and sector were both reobserved complete, with the 

 exception of the shading off round spot No. 1. (See interval 72 to 84 hours, 

 ante,]). 280.) A comiderabh additioii ivas aho well observed. 1°. The sector 

 appeared widened out between spots Nos 3 and 4. 2°. The N.E. streak was 

 traced of the form sketched, and in contact with the border. [This appears 

 to be the earliest instance of the greater reflective power of the northern part 

 of the floor, which is independent of libration, inasmuch as both on August 

 26, when the streak was quite free froin the border, and on this day, when 

 in contact with it, the moon had south latitude. It is also independent of 

 illuminating angle, as it was most extensive and brightest at an interval of 

 24 to 36 hours (see that interval, May 9).] 3°. A tongue of light jutting 

 out from the border on the north of B. and M.'s ^, /. e. the high rock at the 

 east of Plato. [This is the streak »/, first recorded by Mr. Gledhill on Oc- 

 tober 19, 1869.] 40. The sector [or streak] on the north of spot No. 3 spread 

 out as far as the border, and enclosing spots No. 20 and 21. 5°. The streak 

 c made another contact with the border near spot No. 16 [this contact is 

 Webb's elbow]. The streak was connected with the N.W. arm (e) of the 

 trident, being continued beyond its usual termination near spot No. 13, and 

 could be traced to about halfway towards the middle arm (e), beyond which 

 it was quite invisible." [On the next luni-solar day, December 13, 1869, 

 interval 48 to 60 hours, the same general distribution of the streaks, with 

 the extension of the lighter surface to the north border, was seen by Mr. 

 Gledhill (see ante, p. 278).] In Mr. Gledhill's observations of November 15, 

 he does not mention the streaks separately, but gives on the diagram the 

 sector b diverging from spot No. 4. He does not indicate the widening out 

 between spots Nos. 3 and 4, as seen by Mr. Pratt. He gives y and /3 both 

 up to the border, also the streaks a and c, but does not give the continuation 

 into the trident, which it appears he did not observe except the streak B. 



1869, October 16. — Mr. Pratt recorded the junction of the trident as 

 difficult, especially so just west of spot No. 1 ; the sector and c much the 

 brightest. 



Summarif.— Suns altitude 25° 49'-5 to 28° 54' -3 ; tint of floor 0-52, 

 estimated from curve. Streaks generally visible — the sector and trident, the 

 N.E. streaks less frequent ; trident seen complete -with stem on October 16 

 and November 15 by Mr. Pratt. 



Interval 96 to 108 hours. 



1870, April 12. — Mr. Gledhill recorded the floor as dark, =0-66; he de- 

 scribed the streaks as all brighter than on the 11th. Mr. Pratt on the same 

 evening recorded the sector as very easy ; also I, k, c, a, and ft ; 7; was seen, 

 not as a streak, but a tongue of light running from the border towards spot 

 No. 4. The streak n (very rarely seen) was observed extending from spot 

 No. 1 to streak k ; <C and e, the eastern and the middle arms of the trident, were 

 difficult ; the western arm of the trident was very faint. The whole area 

 bounded by spots Nos. 14, 1, and 16 with the western border verrj hazy. 

 Crater G on the exterior N.W. slope well defined at times. 



