L. Trouvelot—Transit of Mercury. 127 
but irregularly and slightly serrated, either by black or grayish 
point is was particularly noticeable on the south preced- 
ing side, where the black disk seemed to be prolonged by a 
short grayish appendage. This peculiarity already observed in 
the morning soon after the first internal contact, was still visible 
during the afternoon when the sky was clear and the image 
steady ; although it was not then so apparent. 
A sharp watch was kept for the luminous ring, and I had 
almost lost all hope of seeing it, when soon after the sky cleared 
up, I saw a short and narrow arc of light hanging on the pre- 
ceding side of the black disc, and a little larger and wider one 
on the following side. Asa few small facule were scattered 
in the vicinity of the planet, I at first thought that Mercury 
was passing over some of these objects, but it soon became evi- 
dent that these luminous ares were really hanging to the dark 
disc, as I could soon see them passing over the solar granulations 
with the planet. Fig. 1. 
* 2. 
. rafal a cern 
Se MIC 
to me that if instead of having been on the granulations, the 
planet had been projected over some brilliant facule, by con- 
trast, it would have appeared surrounded by a grayish instead 
of a luminous ring. The outer edge of the ring did not appear 
sharply detined, except at its brightest parts, but its inner edge 
was much more apparent, and the irregularities of the black 
isc very visible on this luminous background, 
he ring did not appear perfectly concentric with the black 
