112 J. N. Lockyer on the supposed Compound 
“We now turn to the jast and strongest series of protuber- 
ances pane on our photographs. The distance between this 
series and the one we have found reason for ere with 
y is very little greater than that between Hf and Hy. 
Assuming the distances equal, we conclude that the squares of 
the inverse wave- na apes of the three series are in arithmetical 
progression. This is true as a first approximation. We then 
calculated the patalesath of this unknown line, and found it 
to be approximately somewhat smaller than 3,957 tenth-meters. 
No great reliance can be placed, of course, on the number, but 
it appenr that the line must be close to the end of the visible 
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vacuum tubes prepared by Geissler containing hydrogen, 4 
strong line more refrangible than H is seen, but these same 
tubes show between Hy and H6, other lines known not to 
belong to hydrogen, and - Loree of the ultra-violet line is 
therefore difficult to make We have taken the pie in 
a part of ie svn and prevents any observation as 
point. 
“Should it turn out that the line is not due to hydrogen, 
the question will arise what substance it is due to. It is4 
ceo fact that the calculated wave-length comes vely 
oung has found that these calcium lines are 
always sgt erie in the penumbra and immediate neighborhood 
of every important sun-spot, and calcium must therefore go ™P 
high into the chromosphere. We draw attention to this coinel 
dence, a our as Pantgrepys do not allow us to draw any cer 
tain conclus 
“Ata ge te, it seems made out by our photographs that the 
photographic Tight of the protuberances is in great part due t 
an ultra-violet line which does not slag « fas ng to to hydro- 
gen. The protuberances as photographed by this ultra- violet 
seem to go up higher a the ydrogen protuberance; 
ast 
but this may be due to the relative wisp length of the jine.” | 
In my remarks upon calcium I have already referred to 
fact that the line which our checrtgtion led us to believe was 
due to wae in 1875, was traced to that element in this otha 8 
eclipse. he observations also show the curious connection that 
at the leg when the hydrogen lines were most brilliant in the 
corona, the calcium lines ‘were not detected ; next, when 
eae ee ee ee 
