Intelligence and Miscellaneous Articles. 229 



If possible, by means of a graduated pearl scale or other equivalent 

 means, the breadth of the narrowest part of the annulus should be 

 measured several times about the middle of the time of the annular 

 appearance, as well as it can be estimated. 



At other places the eclipse will not be completely annular, and 

 here the principal object must be to make several measures of the 

 distance between the cusps about the time when that distance is 

 smallest. This measure may probably be made by means of a gra- 

 duated pearl scale, or by means of a divided object-glass applied in 

 front of the object-glass of the telescope, or by the use of a common 

 sextant. 



VI. As to the particular points of physical interest to which at- 

 tention should be directed, they may be stated as follows : — 



1 . It will be desirable in general to notice the fact of the appearance 

 of what are denominated " beads " and " threads " by the late Mr. 

 Baily and others, just before and after the completion of the annulus. 



For details of older observations the observer should consult 

 Ast. Soc. Memoirs, i. 142-146, x. 10-17, 33-38. 



The beads were observed by Mr. Baily, ib. x. 210, in 1842, 

 when they were not seen by Mr. Airy, ib. x. 218. 



They were observed by Prof. Henderson at Edinburgh. Ast. 

 Soc. Notices, v. 186. 



2. Whether in the neighbourhood of the cusp the limb either of 

 the sun or moon appears distorted ? 



Whether the beads appear steady or waving, disappearing and 

 reappearing, &c. ? 



See the observations of Mr. Caldecott at Trevandrum, Ast. Soc. 

 Notices, vi. 81. 

 Whether they present any peculiar changes when viewed through 

 differently coloured glasses, the observer alternating the colours, 

 which should be as dissimilar as possible, such as red and green ? 

 See Silliman's Journal, Jan. 1842. 



3. Whether they are seen when the eclipse is projected on a screen? 

 In this way Prof. Chevallier saw none when others with coloured 



glasses saw them. Ast. Soc. Notices, v. 186. 



4. The drawing out of the beads into threads when very near 

 junction; and whether they waver and change, and the number of them? 



See Ast. Soc. Mem., x. 15-17, 39 ; waving and changing, ib. x. 

 12, 13 ; not seen in 1842 by Mr. Baily, Notices, v. 210. 



5. Whether before and after the formation of the threads the 

 moon's dark disc is elongated towards the point of contact ? 



This was observed, ib. x. 29 ; and wavy motion in the limb, 

 ib. X. 12, 14, 30. 



6. The beads are ascribed by some to lunar mountains : What 

 mountains exist at that part of the limb ? 



See Ast. Soc. Mem., X. 9, 16, 30-36. 



7. The exact intervals of time elapsed between the first and last 

 complete contact, and that of the first and last formation of beads or 

 other irregularities in or about the cusps, should be determined. 

 The difiference of the times being all that is wanted, a good ordinary 

 watch will be sufficient. 



