308 
EASTMAN. 
Lecture and the discussion of cometary observations contained 
in this Appendix show that the vapors which are given out 
by the meteorites as the sun is approached are in an ap¬ 
proximate order: slight hydrogen, slight carbon compounds, 
magnesium, sodium, manganese, lead, and iron. Now, of 
these the hydrogen and carbon compounds are alone per¬ 
manent gases, and the idea is that they have been occluded 
as such by the meteorites.” 
“ The aurora being a low temperature phenomenon, we 
should expect to find in its spectrum lines and remnants of 
flutings seen in the spectra of meteorites at low temperatures. 
The characteristic line of the aurora is the remnant of the 
brightest manganese fluting at 558.” 
“ The spectrum of the nebulae, except in some cases, is 
associated with a certain amount of continuous spectrum, 
and meteorites glowing at a low temperature would be com¬ 
petent to give the continuous spectrum with its highest in¬ 
tensity in the yellow part of the spectrum.” 
“ Only seven lines in all have been recorded up to the 
present in the spectra of nebulae, three of which coincide 
with lines in the spectrum of hydrogen and three corre¬ 
spond to lines in magnesium. The magnesium lines rep¬ 
resented are the ultra-violet low-temperature line at 373, the 
line at 470, and the remnant of the magnesium fluting at 
500, the brightest part of the spectrum at the temperature 
of the Bunsen burner. The hydrogen lines are h, F, and 
H y. (434). Sometimes the 500 line is seen alone, but it is 
generally associated with F and a line at 495. The remain¬ 
ing lines do not all appear in one nebulae, but are associated 
one by one with the other three lines.” 
“ When a tube is used in experiments to determine the 
spectrum of meteoric dust at the lowest temperature we find 
that the dust in many cases gives a spectrum containing the 
magnesium fluting at 500, which is characteristic of the 
nebulae and is often seen alone in them. If the difference 
between nebulae and comets is merely of cosmographical 
position, one being out of the solar system and one being in 
