Intelligence and Miscellaneous Articles, 403 



the line F and of the line b in those stars in which they are both 

 perceptible, like Aldebaran, Capella, &c. By this means I have as- 

 certained that the line of hydrogen is pretty well marked, even in a 

 of Orion, although it is not so characteristic as in Sirius, and that 

 it occupies the first place of a dark band after a beautiful band of 

 bright lines in the greenish blue. The stars hitherto examined be- 

 long to Canis Major, to Orion, to Canis Minor, to Leo, to Triangu- 

 lum, to the Bear, to Auriga, to Cassiopeia. 



The conclusion at which we have attained, though negative, is of 

 great importance ; for we have ascertained that among the stars ex- 

 amined there is none whose proper motion is five or six times as great 

 as that of the earth in its orbit. It is undoubtedly possible that we 

 may find similar motions for others ; but to obtain precision in those 

 I have examined means are necessary which at present are not at 

 my disposal. 



As the investigations relative to all the stars are not yet com- 

 pleted, I would have deferred this communication to the Aca- 

 demy until I had finished the examination of the entire heavens, but 

 for a reason which seemed to me important enough to decide me to 

 make it now. In fact the apparatus which I have described appeared 

 to me useful for other circumstances — and especially during solar 

 eclipses, in examining the protuberances. 



From what I remember of the luminous intensity observed of these 

 protuberances in Spain in 1860, I strongly doubt whether we should 

 succeed in analyzing them with a spectroscope with a slit, especially 

 with telescopes of small dimensions, which are the only ones used 

 for this purpose in distant expeditions, and which have not the equa- 

 torial movement given by a clockwork. Without this movement it 

 would be almost impossible to analyze a protuberance with the slit, 

 while with a direct simple spectroscope it could be easily done, since 

 the field is very extensive. The use of the electric spark or of arti- 

 ficial lights might be avoided by introducing the direct rays of the 

 spectroscope, as I do in the case of stars. The protuberances are 

 small enough to be observed with accuracy like the stars ; in fact 

 in the planet Venus I could very well observe the solar lines by 

 using a moderate magnifying-power and a very dispersive prism. 



The corona alone might be observed with the slit ; for it has too 

 great a superficies to enable us to distinguish the lines with the 

 simple spectroscope. But I think that with this instrument the 

 protuberances might be very well analyzed with a telescope of 10 

 centims. aperture. In any case it would be well to choose a tele- 

 scope of at least 6 inches ; for the relative intensity of the protube- 

 rances is greatly enfeebled by the light of the corona on which they 

 are projected ; moreover it seems that their radiation is more re- 

 markable for its chemical than for its luminous intensity. 



I may apologize for this digression, which is inspired by the inter- 

 est which all men of science take in the remarkable phenomenon we 

 expect next August. — Comptes Rendus, March 2, 1868. 



