80 REPORT— 1871. 



and well defined ; this, as well as the remarks of Mr. Elger on May 9, may 

 tend to throw some light on the decreased visibility of Nos. 13 and 19 (see 

 Interval 24 to 36 hours). On this evening Mr. Whitley observed and described 

 the markings, giving a sketch of the same. Mr. Elger's sketch of the north 

 part of Plato and Mr. Whitley's are not in accordance. The time at which Mr. 

 Whitley made his observations is not mentioned; Mr. Elger's 8.45 to 11. 



1870, March 14. Mr. Elger writes : "The markings were not well seen; 

 the eastern arm of the ' trident' was the brightest, and could be traced from 

 the south rim to Jfo. 1, passing to the west of No. 5 : the marking y was 

 very plain, the rest of the markings were faint and difficult to make out." In 

 contrast with this indistinctness on Plato, Mr. Elger says, " [In spite of the hazi- 

 ness of the sky, the markings and minute details of the Mare Tnibnuni were seen 

 with unusual distinctness]." In the 'English Mechanic,' No. 312, March 17, 

 1871, p. 602, article "Mars," by E.R.A.S., the author speaks of the indi- 

 stinctness and partial dimming on the surface of the planet, accompanied by 

 the presence of dark lines in its spectrum, coincident with those referable 

 by Father Secchi to the vapour of water. The indistinctness and dimming 

 of detail are alike distinguishable on Mars and the Moon ; and in addition we 

 have on the Moon a number of spots becoming vividly bright with a high 

 sun. From Dr. Huggins's observations, the spectral lines of the vapour of 

 water are absent in the lunar spectrum. 



1870, June 10. Mr. Elger recorded No. 17 decidedly brighter than No. 5 and 

 equal to No. 3; 14 only glimpsed once or twice ; 16 and 25 frequently seen. 



1869, December 15. This evening Mr. Elger discovered spot No. 32. He 

 described it as N.E. of spot No. 3, nearly aligning with 17 and 4, and situ- 

 ated on a brush of light (GledhiU's streak /3), extending from No. 3 to the 

 N.E. rim of Plato. 



1871, March 3. Mr. Pratt observed 16 spots, viz. 1, 3, 4, 5, 14, 17, 21, 

 20, 23, 29, 0, 18, 13, 19, 7, 6, arranged according to relative brightness. 

 Of these Mr. Pratt speaks of Nos. 20 and 21 as being far above their usual 

 brightness. Situated as they are near the north border, the Moon going 

 north in latitude, they were not in the most favourable position for observa- 

 tion ; their great brightness is therefore remarkable, and connected with this 

 is an increase of brightness in the streak a. The new streak between Nos. 5 

 and 17 Mr. Pratt saw with ease, joining the east arm of the "trident" with 

 the " sector" from closely south of 17 to opposite 5. 



1870, October 6. Mr. Gledhill records Nos. 1, 17, and 30 as fine bright 

 disks ; Nos. 5 and 6 equal. Mr. Elger observed Nos. 14 and 16, not seen by 

 Mr. Gledhill ; 14 was equal to 5. 



Interval 108 to 120 hours, 



1870, September 7. Mr. GledhiU records Nos. 1 and 3 as fine sparkling 

 disks, and 4 as a hazy spot. Mr. Neison records Nos. 1, 3, 4, and 5 pretty 

 distinctly visible; 17 brilliant but not well defined; 14 and 16 faint and 

 very faint respectively. 



1869, November 16. Mr. GledhUl says, " I never saw the floor so bright. 

 The spots 1, 17, 9, 3, and 30 appeared just like small stars in the transit- 

 instrument on a windy night." At 10, 11, and 12 hours Mr. Gledhill 

 remarked that spots Nos. 3, 1, 9, and 17 formed a sparkling curve, and were 

 fine easy objects, seen at a glance at any moment ; he says they were very 

 striking. On the contrary, he speaks of spots 23, 16, 19, 13, and 14 as very 

 difficult objects ; none were ever easy objects. Of 9 and 11 he says, " I 

 never saw them so easily and well as to-night." The following notes are 



