Intelligence and Miscellaneous Articles, 79 



It thus appears that hydrogen is the chief constituent of the stars 

 of this group. The peculiar phenomena in y Cassiopeia, where, in- 

 stead of the dark line/, there is a bright one, might be explained 

 by the fact that hydrogen gives at low temperatures a continuous spec- 

 trum in which the line /is bright, and that hydrogen, when present 

 in small quantity, does not invert the spectrum. There are doubtless 

 other lines between those of hydrogen, but they are relatively very 

 feeble ; the most prominent are those of magnesium and of sodium. 

 The second type, that of a Herculis, is far less numerous, but is re- 

 markably constant. Direct measurements gave exactly the same 

 lines in the same places in all stars of this type. The only difference 

 is in the circumstance that in the normal stars a Herculis, (3 Pegasi, 

 o Ceti, p Persei, the lines which separate the columns are quite sharp 

 and dark ; while in some, as in a Ononis and a Scorpionis, they occur, 

 though rather weak, in the less-refrangible part of the spectrum. 

 This peculiarity might be thought to indicate a difference which in 

 fact dees not exist. 



It is curious that this type embraces the strongly red-coloured and 

 the variable stars. The star o Ceti (Mira) is a remarkable proof of 

 this; I observed it last September, but its smallness did not justify 

 any conclusions. In March it was of the fourth and fifth magni- 

 tudes ; it exhibited the colonnade of a Herculis with surprising accu- 

 racy ; its feebleness, however, caused its spectrum to appear shorter, 

 and the outside lines to lie closer. The red star of Auriga (Lalande 

 12581) (right ascension 6 h 27 m , declination 38° 33') belongs also to 

 this type ; only the second and third columns coalesce, as well as also 

 the fourth and fifth. It is indeed surprising to observe such iden- 

 tity in the spectra of various stars. I imagine that the stars belong- 

 ing to this type are tolerably numerous ; but their colour is so dark 

 that their characters cannot be determined. 



The third type, that of the sun, would seem from its nature to 

 present a great number of differences ; yet this is not the case. The 

 chief differences are that there are fine lines in more or less compact 

 groups ; but these lines have the same position, which is not that of 

 the previous type. The magnesium line, which is very much deve- 

 loped in the third type, does not show the same union of adjacent 

 lines as in the second type ; moreover in the third type the line/ can 

 always be readily distinguished, while it is wanting in the second. 

 Owing to these differences it is easy to discriminate this type from 

 the others, even if the lines are so grouped that they appear similar 

 to it. The doubtful cases which I have met with may be resolved 

 by subsequent measurements undertaken at leisure. 



Certain types are peculiar to certain regions of the heavens, even 

 when the number of stars is tolerably large. The type Orion cha- 

 racterizes one portion of the image of the Dog and the Hare, but is 

 scarce in other parts of the heavens ; green predominates in these 

 stars, which is characteristic of the nebulae. The yellow stars, which 

 belong to the third type, are very numerous in the Whale and in 

 Eridanus. The Ox is formed exclusively of stars of the first type, 

 Aldebaran and some others excepted. 



