136 cosmos. 



That part of the Moon's edge which was not projected 

 upon the Sun's disk again became perceptible, especially 

 during the egress.* 



A group of Sun-spots was visible, though some minutes 

 distant from the edge of the Sun, where the largest red, 

 hook-formed projection was developed. On the opposite side, 

 not far from the feeble eastern projection, there was also a 

 Sun-spot near the edge. It is scarcely possible that these 

 funnel-shaped depressions can have furnished the material 

 constituting the red gaseous exhalations, on account of the 

 distance above mentioned ; but as the whole surface of the 

 Sun appears to be covered with pores, perhaps the most 

 probable conjecture is, that the same emanation of vapor and 

 gas, which, rising from the body of the Sun, forms the fun- 

 nels,! pours through these, which appear to us as Sun-spots 



* This outline of the Moon, clearly perceived by four observers dur- 

 ing the total eclipse of the Sun on the 8th of July, 1842, was never pre- 

 viously described as having been seen during similar eclipses. The 

 possibility of seeing an exterior outline appears to depend upon the 

 light which is given by the third outermost envelope of the Sun and 

 the ring of light (corona). " La Lune se projette en partie sur l'atmo- 

 sphere du Soleil. Dans la portion de la lunette ou l'image de la Lune 

 se forme, il n'y a que la lumiere provenant de l'atmosphere terrestre. 

 La Lune ne fournit rien de sensible, et, semblable a un ecran, elle ar- 

 rete tout ce qui provient de plus loin et lui correspond. En dehors de 

 cette image, et precisement a partir de son bord, le champ est eclaire 

 a la fois par la lumiere de l'atmosphere terrestre et par la lumiere de 

 V atmosphere solairc. Supposons que ces deux lumieres reunies forment 

 un total plus fort de ^L que la lumiere atmospherique terrestre, et, des 

 ce moment, le bord de la Lune sera visible. Ce genre de vision peut 

 prendre le nom de vision negative ; c'est en effet par une moindre intensity 

 de la portion du champ de la lunette ou existe l'image de la Lune, que le 

 contour de cette image est aper9ii. Si l'image etait plus intense que le 

 reste du champ, la vision serait positive." — Arago, Annuaire du Bureau 

 des Longitudes, p. 384. " The Moon is projected partially upon the at- 

 mosphere of the Sun. In that portion of the telescope where the image 

 of the Moon is formed, no other light enters except that of the terres- 

 trial atmosphere. The Moon gives no sensible light, and, like a screen, 

 it stops all that which comes from beyond and corresponds with it. 

 Outside the image, and immediately round its edge, the field is lighted 

 simultaneously by the light of the terrestrial atmosphere and by that of 

 the solar atmosphere. If we suppose that these two lights collectively 

 are J- stronger than the light of the terrestrial atmosphere, the Moon's 

 edge will be directly visible. This kind of vision may be designated 

 a negative vision, for it is, in fact, by the less intensity of that portion of 

 the field of the telescope in which is the image of the Moon, that the 

 outline of this image is perceptible. If this image were more intense 

 than the remaining part of the field, the vision would be positive." 

 (Compare also, on this subject, Cosmos, vol. iii., p. 56, note *.) 



* Cosmos, vol. iv., p. 63-o"7. 



