298 R. Meldola—Bright Lines in the Solar Spectrum. 
The e hypothesis of a zone of combustion in the higher regions 
of the sun’s atmosphere, as already stated, furnishes suggestions 
for the explanation of many observed facts in solar physics 
hitherto unaccounted for 
T will first call attention to the intense brilliancy of the line 
D,; in the s watgsiccss of the chromosphere, and ‘the extreme 
i 
a ray of light emitted by the photosphere should be barely suffi- 
cient to reverse its spectrum. If the existence of a zone of com- 
bustion be granted, however, this region becomes the source of 
radiation of all gases which extend so far. Thus in the case of 
the D; element, which reaches ais the same level in the sun’s 
atmosphere as hydrogen, the stratum of gas exterior to the zone 
of combustion is, on the present view, alone concerned in revers- 
ing the line under consideration ; and this stratum may be of 
insufficient thickness to produce any marked absorption. The 
“1474” substance, however, which rises far above hydrogen, ap- 
ears to exist in sufficient quantity exterior to the supposed re- 
gion of combustion (or its specific absorptive power is sufficiently 
semen and aebanialatiens of oe quantities of compoan 
phere. The 
zone of combustion may be, so to speak, only a local phenome- 
* This line was seen in July, 1877, by H. C. Russell, at Sydney. The observer 
states that “‘it is a difficult line to see, and ow sw made out with high powers. 
The greatest dispersion of the s ig ge ployed was equal to eighteen 64° 
eor ns (Month. Not. Roy. Astr. Soc., Nov. 9. ST, pp. 30-32). 
r has wn (Compt. Proc. Roy. Soc., 
xxvii, a8) "that the blue line of lithium (w.-l. 4603) is represented in the solar 
spectrum, while the red line (w.- 05) has not hithe n detected. The 
i i hether the abse e may not also be 
existence of a region of busti The low atomic weight 
of lithium would lead to this element extends to a _ height in 
o bustion might be the source of 
the so! 
lithium eeepc and at the temperature of the sun the blue ine adh be the 
be sufficient to reverse eg blue, but insufficient to cite es hori red line. 
would here ask whether the bright red line so frequen f 
the chromosphere by gaan 9 1060, pp. 228 and nd 429), yan described 
as being less refrangible , may not be th pee 
a line] ‘ refrangible than C peo frequently in ogi eg a 
base of PrOeees. It i ly significant that di the eye 2 of 1868 ; 
blue line between F and G was seen by Rayet in the 
this is Ghe position that would be coset Ge Gas kine tee ot 4803. 
