of the Total Eclipse of July 28, 1851. 105" 



27. Any observations for intensity, polarization, &c., which 

 were omitted before the total obscuration, can now be made 

 in a leisurely manner: and some measures of the interval 

 between the cusps may be made with the sextant. 



28. During the remainder of the eclipse there will be little 

 of interest to be done, except to repeat the observations of 

 radiation, and to make any observations applying to the me- 

 teorological state of the atmosphere. The instant of termi- 

 nation of the eclipse (a phenomenon which admits of accurate 

 observation) should be noted. The actinometer-observations 

 should be continued to a quarter of an hour after the last 

 contact. 



Appendix No. I. 



The following suggestions applying specially to the obser- 

 vation of the beads or strings sometimes seen, are principally 

 extracted from the " Suggestions for the observation of the 

 Annular Eclipse, October 9, 1817," in the Beport of the Seven- 

 teenth Meeting of tite British Association^ Transactions of the 

 Sections, p. 16. 



Whether the points of the cups are rounded ? 



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 ? 

 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 ? 



Whether they are seen when the telescope is out of focus ] 



Whether they are seen when the eclipse is projected on a 

 screen ? 



The drawing out of the beads into threads when very near 

 junction ; and whether they waver and change, and the num- 

 ber of them ? 



Whether before and after the formation of the threads 

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

 contact ? 



The beads are ascribed by some to lunar mountains. What 

 mountains exist at that part of the limb % 



The exact interval of time between the first formation of 

 beads and the first complete contact, and that between the 



