266 . REPOiiT— ISrS. 



brightness on the north-west portion of the floor appears to have declined 

 since May 9. 



Lunation July 1870, from 117 hoiivs hefore to 81 hours after meridian 



passage. 



Three observations were obtained in this lunation, — on July 8, 60 to 72 

 hours after sunrise, when streak a was seen as a bright object ; on July 1-i 

 and 16, from 156 to 96 hours before sunset, a condensed brightness in the 

 central part of streak a being witnessed. 



Lunation August 1870, from 9 hours before to 141 hours after meridian 



^oassage. 



Three observations are the only ones recorded, the first ou Augaist 11 near 

 meridian. In a drawing by Mr. Elger streak a is shown as very narrow, 

 and quite separated from the north border, the west end crossed by the 

 projection c from Webb's elbow ; " o " was not seen. On the 13th the streak 

 was seen by Mr. GledhUI, a dark tint of iioor being recorded by Mr. Pratt. 

 On the 17th the streak was recorded by Mr. GledhUl as the brightest amongst 

 the faint streaks observed. 



Lunation October 1870, from 81 hours before to meridian passage. 



Two observations only were obtained, — the first on October 6, interval 96 

 to 108 hours, when streak c was seen quite detached from the border, and 

 figured as narrow by Mr, Elger ; the second on October 9, seen near meri- 

 dian, when it (a) was shown as narrow by Mr. Elger, quite separated from 

 the north border, the west end crossed by Webb's elbow and c ; these toge- 

 ther form a curved streak, concave towards the west border (see ante, pp. 263- 

 265), the continuation " o " being entirely absent. 



Lunation January 1871, from 168 to 132 hours before sunset. 



In the first of two observations in this lunation, made on January 7, the 

 north-west part of the floor is recorded as being in the same state as in 

 August 1869 (see post, p. 269) ; in the second, on January 8, Mr. Gledhill 

 recorded the streak a as sharply defined, bright, narrow, and straight. 



Lunation March 1871, from interval 72 to 81 hours to interval 96 to 108 



hours after sunrise. 



On the second interval, 72 to 8-1 hours, the streak a was seen extending 

 from spot No. 19 to spots Nos. 20 and 21 ; it is described as having been 

 very distinct. On the third interval. 96 to 108 hours, it was observed by 

 3Ir. Pratt as the fourth in order of brightness, the sector k and /3 being brighter. 



Erratum. — Fig. 9, p. 263, dele connexion between streaks ^ and e ; not in 

 original. 



*»' 



In the Eeport Brit. Assoc. 1871, p. 66, the position of streak a is given 

 as determined by three sets of measures by Mr. Gledhill of the two ends of 

 the streak on September 13 and December 9, 1870, and May 1, 1871. The 

 streak is shown in fig. 4 of that Eeport as long and narrow. The numerous 

 observations of the floor, including those of streak a, show that not only is 

 the north-west part of the floor variable as regards its tint (light or dark), 

 but that the positions of the streaks are also variable ; and this variation is 

 confirmed by the measures, which differ in value just as the recorded posi- 



