Intelligence and Miscellaneous Articles. 241 



it. The eye, relieved in this way from the bright solar spectrum, 

 would be in a more favourable state to examine the fainter spectrum 

 of the red prominence. 



Four of these instruments, made by Mr. Browning, have been 

 sent out by the Royal Society to India, to be placed in the hands 

 of observers stationed at different places along the central line of the 

 eclipse. This instrument would be specially suitable for use at sea. 



Postscript. — Mr. Browning has recently suggested a method of 

 diminishing the apparent velocity of meteors by the use of a con- 

 cave cylindrical lens placed with its axis perpendicular to the direc- 

 tion of their motion. This mode of observing may be applied to 

 the spectrum-telescope by substituting, when required, a plano-con- 

 vex cylindrical lens for the eye-lens of the eyepiece. If this lens be 

 placed with its axis parallel to the height of the compound prism 

 before the object-glass, and if the telescope be held in a position 

 such that the direction in which the light of the meteor is dispersed 

 is perpendicular to that of its motion, the spectrum of the meteor 

 will be magnified, as when the ordinary eye-lens is employed, but 

 the apparent velocity of the meteor will be less by an amount equal 

 to the magnifying -power of the eye-lens. 



XXVII. Intelligence and Miscellaneous Articles. 



ON STELLAR SPECTRA. BY FATHER SECCHI. 



T BEG to offer a continuation of my last communication on stellar 

 ■*■ spectra (Phil. Mag. vol. xxxv. p. 78). In continuing these inves- 

 tigations I was led to examine the red stars in order to ascertain 

 whether my supposition as to the nature of their spectra was 

 justified. 



A good catalogue of these stars is found in the Connaissance des 

 Temps, vol. xv., drawn up by Lalande ; and there is a more extensive 

 and complete one in the Astronomische Nachrichten, No. 1591. I have 

 examined a great number of those now visible, down to the 8th mag- 

 nitude. This limit is necessary, owing to the direct light of the sky, 

 which gives so much brightness in the field that the light of the small- 

 est stars spread by dispersion is no longer recognizable. It is seen 

 merely in the case of the nebulas, which only exhibit a very small 

 dispersion for some rays. There is thus probably an absolute limit, 

 even with a more powerful lens than one of nine inches. 



The conclusions at which I have arrived are as follows : — 



I. The red stars have generally spectra of the third type (like 

 a Orion, a Herculis, jS Pegasi, Antares, o Ceti ; when the colour is 

 pale, they might be referred to one intermediate to the second and 

 third. 



IL The spectra of a great number of these stars of the 5th or 

 6th magnitude are perfectly resolvable into bands, which again can 

 be resolved into lines more or less spread out. Such are the fol- 

 lowing : — 



Phil Mag. S. 4. Vol. 35. No. 236. March 1868. E 



