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with the spectrum of the star. Thus, for example, while the 
eye was receiving the lines from the spectrum produced from 
the hght of Aldebaran, spectra of sodium, magnesium, or of 
other metals, were formed beside the astral spectrum. By this 
means it was determined that the lines produced by the 
spectra of sodiurrij magnesiurrij hydrogerij calcium^ iron, tel- 
lurium, antimony, and bismuth, were coincident with certain 
hnes in the spectrum of the star.* Seven other elements were 
compared with this star without any coincidence being 
detected; these were nitrogen, cobalt, tin, lead, cadmium, 
lithium, and barium. The spectrum of a Orionis comes next 
under consideration. The light of this star has an orange 
tinge ; none of the stars which we have examined,^^ write the 
observers, have a more complex or remarkable spectrum than 
this.^^ The spectra obtained from sixteen elementary bodies 
were observed simultaneously with the spectrum of this star. 
Of these, five only were found to present corresponding lines ; 
these were the lines of sodium, magnesium, calcium, iron, and 
bismuth, |3 Pegasi exhibited a spectrum very nearly re- 
sembling that of a Orionis ; two elements only have been 
satisfactorily determined as corresponding with lines in this 
spectrum ; those are sodium and magnesium ; and a third, 
barium, is probable. Sirius may be regarded as still under 
examination; four elementary bodies have been found to 
furnish spectra in which lines coincide with those of Sirius ; 
viz., sodium, magnesium, hydrogeiij and probably iron. 
- a Lyrae, Capella, Arcturus, Pollux, a Cygni, and Procion, 
have been all examined in the relations of their spectra to the 
lines of the metallic spectra. Sodium, hydrogen, magnesium, 
and iron have been detected. 
Pig. 5 shows the spectra of the double star j3 Cygni. By a 
very ingenious arrangement, the spectra of those stars are 
formed at the same time in the instrument. The hnes and 
bands in those spectra have not yet been measured, and 
these figures must be regarded as eye- estimations only of 
the general features of the two spectra.^^ In the spectrum A, 
the light of which is yellow tinted with orange, the absorp- 
tion is greatest in the violet and the blue ; for the strong lines 
in the orange and red, since they are narrow, would diminish 
in a much smaller degree the hght of these refrangibihties. 
The yellow and part of the green are free from strong hnes. 
The hght of the star giving the spectrum marked B ap- 
pears blue, passing, however, into green and greenish white. 
* These lines are marked on the plate as follows : — Fe, Iron ; Bi, Bismuth ; 
TZ, Tellurium ; Ca, Calcium ; Na, Sodium ; Bb, Antimony ; Mg, magnesium ; 
JSg, Hydrogen. N (fig. 6) is Nitrogen ; and Ba, Barium. 
