OBSERVATIONS OF LUNAR OBJECTS. 87 



small localities, there does appear to have been a wider and more gene- 

 ral disturbance in the brightness and definition of objects, all which dis- 

 turbance appears to be confined to the loiu-lying lands of that part of the 

 moon observed. Not that changes were not visible in high regions ; but 

 those are more easily referred to changes of illuminating and visual angle, 

 while the disturbances above mentioned are not so easily accounted for, 

 especially those changes in the visibUity of the light-streaks on the floor 

 and the striking differences of brightness of the spots." 



1809, October 26. In connexion with Mr. Gledhill's return of this date 

 I remark, " 'Crater Eow' being so well seen, and the border of Plato so sharp 

 and distinct, it is remarkable that spots Nos. 5, 6, 7, 13, 14, and 16 should 

 not have been well and easily seen, although it appears they were seen, also 

 that spot No. 3 should have been seen single, and that only sometimes, when ifc 

 was seen double the previous night." 



1870, November 14. Mr. Gledhill observed Nos. 1, 3, 30, and 17 as 

 craters, and says, " they look like bright elevated rings." 



Interval 24 to 12 hours. 

 1870, March 23. See ante. Interval 36 to 24 hours. 



1869, September 27. Mr. Gledhill recorded a broad band of brightness 

 parallel to the north border, enclosing spots Nos. 13, 19, and 16 ; he does 

 not say they were seen as well as the bright baud. I have, however, re- 

 corded them as having been seen. 



Interval 12 to hours or sunset. 



1870, November 15. The four craterlets Nos. 1, 3, 30, and 17 are de- 

 scribed by Mr. Gledhill as elevated crater-cones. 



1870, March 24. Mr. GledhiU writes :—" Terminator on N.E. end of 

 Apennines ; the eastern shadows lie on the floor. A line drawn along 

 the west edge of the ' sector,' and produced to the north border, separates 

 the bright east part of the floor from the darker west part ; the inner slope 

 of the west wall glows in sunlight, while the floor near it is the darkest 

 portion of the crater [Plato]." See ]}. 95, line 9. 



Additional Notes. 

 Differences of Visibility of neighbouring Objects. 



1869, August 26, 11 hours 30 minutes. Definition frequently exceed- 

 ingly good but disturbed, with much boiling at times. Mr. Pratt has fur- 

 nished the following record : — 



" There was a marked difference between the M. Imbnum, the M. 

 Serenitatis, and the M. Frigoris, in respect of the visibility of minute objects 

 on their surfaces. The Mare Imbrium was literally covered with small white 

 sjwts and streaks. The three streaks from Aristillus to the south border of 

 Plato were again traced. Archimedes had roughly four light streaks E. and 

 W., and about nine or ten easily discerned white spots. Beer and Mddler 

 and neighbourhood looked invitingly for a close study. 



" The Mare Serenitatis was of a dull grey, with few white spots and 

 comparatively few features visible. Gf those visible all were very indistinct, 

 EXCEPT THE MORE ELEVATED ONES ; thus, of the Small objects rouud Linne, 

 most were invisible, a few indistinct, even I E«i, I E^^, I Ev^ [the three small 

 craters N.W. of Linne] were almost obscured. Linne itself a cloudy white 

 spot, with knot of light in centre, but not nearly so bright as when seen 

 on the 23rd inst. Posidonius y was brighter and half the size of Linne. 

 Vessel was tolerably clear. About half the number of white spots S.E. of 



