84 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



planet was surrounded by a ring of light, as bright as the 

 Sun, that pushed the edge away from it; and no actual con- 

 tact could be observed." And yet there was no black drop, 

 no ligament and no distortion reported by the observer. 



It is admitted that there is no atmosphere enveloping 

 the Moon, and yet Royal Astronomer Stone at the Cape of 

 Good Hope observed the outline of the Moon projected 

 against the Sun's corona five minutes and eight seconds 

 before the total phase of a solar eclipse. We reported a very 

 faint exhibition of this phenomenon January nth, 1880. 

 If the corona of the Sun is the visible arc of illumination in 

 this case through contrast, we are entirely justified in as- 

 suming it to be the agent of illumination at the circumfer- 

 ence of Venus; and on account of the irregularity and 

 inequality of the brightest parts of the corona, it may be 

 seen at one part of the planet's circumference and not at 

 another, or it may be seen all around the planet. A critical 

 examination of the reports clearly demonstrates that this 

 faint illumination on the border of the dark body of the 

 planet is seen as (i) part of a circumference; (2) at dif- 

 ferent parts of the circumference; (3) of varying breadth 

 at different points of its length by the same observer; (4) 

 as wholly encircling the planet. If it were the atmosphere 

 of Venus it would be uniform and continuous, unless a 

 Venus cloud system interfered irregularly. Professor 

 Young says (p. 159) that at a total solar eclipse there is 

 "not any ring of light running out on the edge of the Moon 

 like that which encircles the disc of Venus at the time of 

 the transit." 



With a slight digression, we mention one or two vagaries 

 of observers of the transits of Mercury. 



At one of the recent transits where the observers were 

 side by side, one reported the "definition of Mercury sharp 

 and steady," and the "limb of the Sun undulating," as if the 

 two objects were unequally affected. The other observer 

 described the "limbs of the Sun and Mercury loosely con- 

 nected by a patch of haziness oscillating between them;" 

 and at another phase the "undulations of the Sun's limb 



