83 REPORT 1S71. 



yious impressions ; and I rather fear that telescopes much larger than my 

 own cannot help us out of the difficulty." 



The difficulty to which Mr. Pratt alludes is particularly felt with regard 

 to that indispensable method of determining positions " measirrement." Mr. 

 GledhUl has executed some measures of the positions of the principal spots 

 and the extremities of the light markings, and Mr. Pratt has aligned several 

 of the spots with objects on the border ; but so exceedingly delicate are the 

 details, and so seldom is the state of the atmosphere siifficiently translucent 

 and free from agitation, that to obtain an approximate plan of the spots and 

 markings from measurement is necessarily a work of time. Pending this, 

 in the above sketch both spots and markings have been inserted, partly on 

 alignment and partly bj' estimation. The two light regions are well sprink- 

 led with spots, as pointed out by Mr. Elger ; and it is not a Kttle interesting 

 to notice that the nearly spotless area coincides with the region between- 

 the "trident" and the " sector," with its prolongation to " Webb's Elbow" 

 near the X.W. border. In the absence of more accurate detail, which is likely 

 to be obtained from Mr. GledhiU's measurements, the sketch (fig. 7) will serve 

 as a guide for ascertaining if the spots and markings preserve their relative 

 positions ; and in this connexion the remarkable change of locality, if it be so, 

 of spot Xo. 5 may be mentioned, Mr. Elger having seen and recorded on three 

 occasions (1870, March 14, May 13, and October 10) its position on the eastern 

 edge of the eastern arm of the " trident." It is possible there may be two 

 neighbouring spots in this locality which have not yet been seen together. The 

 importance of recording with eveiy obsei'vation of spot Xo. 5 its position with 

 regard to the eastern ann of the "trident" is obvious. The light streak 

 supposed to be connected with No. 5 is too far south, or the sjjot is too far north,' 

 on the sketch. 



1870, May 13. Vide " Indications of intermittent visibility" (p. 88). 



1870, January 15. Mr. Gledhill observed as many as 22 spots, the second 

 greater number seen on any one occasion. Vide " Indications of inter- 

 mittent visibility." Spots Xos. 1, 3, and 17 are described as very easy, large, 

 bright, sharp objects ; Xo. 4 as jumping into view and not steadily seen. 

 Xo. 34 was discovered this evening ; it has not been observed since 

 March 13, 1870, when it was recorded as an easy object. 



1869, August 20, 21, and 23. Mr. Gledhill gives thi-ee spots close to the 

 X.W. border, which he has marked 13, 19, and 16. No. 16 being too far 

 east for that spot, I have regarded it as 20 ; if, however, Mr. Gledhill really 

 saw 16, its degree of visibility would be shghtly increased. On August 23 

 Mr. Pratt gives 16 in its proper position, and he observed the same number of 

 spots as Mr. GledhiU ; but Mr. Gledhill saw No. 12 and 31, which Mr. Pratt 

 did not see, Mr. Pratt recording Nos. 7 and 30, not seen by Mr. Gledhill. 



1870, September 8. Mr. Neison records spot No. 4 as a flat indistinct 

 spot; 17 sharp but bright, darkening on one side, and showing traces of a 

 crater-formation. 



Interval 144 to 156 hours. 



1870, August 10. Mr. Neison records spot No. 3 as apparently oval ; the 

 longer axis of the ellipse is in the direction of No. 31 . 



1870, October 8. Mr. Elger mentions No. 14 as very easy, 16 easy, and 

 17 seen only occasionally. 



Interval 156 to 168 hours. 

 1870, May 14. Mr. Elger recorded No. 16 easy; 5, 14, and 17 faint; 25 

 and 32 seen by glimpses. Mr. GledhiU records 1, 17, 3, and 6 as bright 

 disks. 4 not well seen, and 5 as a bright spot. 



