272 Secclii and Faye on the Sun. — Observations by Ghacornac. 



and nofc in front. He likewise recommends a blackened paper 

 to be placed behind the collodion film to absorb the light and 

 prevent reflection. 



OBSEEVATIONS BY M. CHACOEFAC. 



We are indebted to M. Chacornac for a copy of Bulletin 

 des Observations faites a Ville-Urbanne, on some groups of 

 sun spots seen on the 6th March, 1865, at 9h. Om. On this 

 occasion the regions of the penumbrse exhibited a series of 

 layers superposed in echelon. This appearance, M. Chacornac 

 remarks, is not rare, but in this case it coincided with an 

 analogous disposition of the interior strata, plunging down into 

 the dark regions of the central body. 



M. Chacornac observes that when spots close up it is nearly 

 always possible to perceive in their depths bridges, which take 

 the form of meshes of a net-work formed of a glutinous matter 

 (matiere glutineuse) , the superficial layers corresponding with 

 others at greater depths. In the spots seen at the above date 

 " the meshes of the pasty matter (corps pdteux) lying beneath 

 the photosphere had a stretched- out appearance, evidently 

 arising from traction movements operating in different direc- 

 tions, either by the expansive force of the gas visibly escaping 

 from the orifices, or by the fall of strata, which seemed to 

 plunge towards the centre through the weakening of the 

 strata that supported them ; or perhaps by reason of move- 

 ments of translation occurring in deep strata, and due to 

 currents in a direction opposite to those of the upper layers. 

 These phenomena show an evident relation between the pasty 

 shell (ecorce) and the liquid medium of the centre." 



M. Chacornac refers the formation of spots to two sorts of 

 actions. In the one he says it is like the enlargement of an 

 originally-formed aperture by the escape of vapours from a 

 pasty mass in fermentation. In the other it is as if the surface 

 was engulphed at certain points in such a manner as to form 

 an elevated margin, with a slope or talus more or less inclined 

 to the solar surface. This configuration has the aspect of vent 

 holes (soupiraux), having their axes inclined to a normal to the 

 sun's surface. 



When a large spot suddenly appears, the engulphing action 

 takes place at all points of the circumference, and almost simul- 

 taneously. " The changes effected by the concurrence of the 

 two kinds of action cause a dispersion of incandescence chiefly 

 in a vertical direction, and the spot no longer exhibits a pe- 

 numbra." When the engulphing action is rapid, it swallows 

 up small adjacent spots, and the size of the chief one becomes 

 enlarged. From the vicinity of several centres of activity, 



