Solar Eclipse 0/ Jult/ 28, IS51, 79 



if total in 1833, would, if central, be total (not annular) in 

 1842 ; and so on for four periods of nine years. 



The Lecturer then called attention to the great difference 

 in the directions of the shadow-paths across Europe, for the 

 eclipses of 1J842 and 1851 : (the former being from W.S.W. 

 to E.N.E. nearly, the latter from N.W. to S.E. nearly). 

 This arose in part from the circumstance that (as above ex- 

 plained) the former of these eclipses occurred when the node 

 or end of the intersection-line of the planes of orbits, turned 

 towards the July sun, was that at which the moon rises to 

 the north of the ecliptic, the latter when it is that at which 

 the moon is descending to the south of the ecliptic. But the 

 principal cause of the difference is this ; that the former 

 eclipse occurred early in the morning, the latter in the after- 

 noon : on placing a terrestrial globe in the proper position 

 for July, with its north pole inclined considerably towards 

 the sun, it is seen that, even if the moon moved precisely in 

 the ecliptic, the path of her shadow across Europe before 

 Europe came to the meridian would trend from the south to 

 the north ; but if Europe had passed the meridian it would 

 trend from the north to the south. 



Quitting the geometrical explanations, the Lecturer then 

 proceeded to describe some peculiar phenomena which had 

 been observed in eclipses, and first, one which had been ob- 

 served most distinctly in annular eclipses, and which is 

 known by the name of " Baily's beads and strings." When 

 the preceding limb of the moon, traversing the sun*s disk, 

 approaches very near the sun's limb, or when the following 

 limb of the moon is in the act of separating from the sun's 

 limb to enter on the sun's disk, the two limbs are joined for 

 a time — (no one has estimated the duration with accuracy) 

 — by alterations of black and white points or strings. Phe- 

 nomena, evidently of the same class, have been observed in 

 the transits of Venus and Mercury over the sun's disk ; the 

 black planet, when just lodged on the sun's disk, being pear- 

 shaped, with its point attached to the black sky. The Lec- 

 turer was able to stat^, in his own experience at the Royal 

 Observatory, that at the same transit of Mercury this pheno- 

 menon was seen witli some telescopes and was not seen with 



