364 Proceedings of the Royal Society 
been able to enlarge the number of lines distinctly characterised 
from 1400 to 2000. 
The reason why Angstrom’s table was deficient in these respects 
probably arose from the less favourable position at Upsala for 
obtaining the sun’s rays. When the body of the sun is near the 
horizon, as it always is in Northern Europe, its rays before reaching 
the earth must pass through a thicker and denser portion of the 
earth’s atmosphere than when it is at a greater angle of elevation. 
At Lisbon the observations could be, and were, taken by Professor 
Smyth when the sun was at an altitude of 70°, whereas at Upsala 
it would be much lower even at noon. 
Professor Smyth’s tables of these black lines interspersed among 
the different prismatic colours are of a most elaborate, comprehensive, 
and evidently trustworthy character. When he had doubts 
whether any of the black lines might not have been produced, or 
at all events affected, by the vapours of the earth’s atmosphere, he 
feays so. 
The great astronomical value of this table will be at once 
recognised by men of science when it becomes known ; for it will 
afford the means of ascertaining whether any secular change takes 
place in the composition or condition of the sun’s atmosphere, or in 
the more solid subjacent parts of that luminary. 
I understand that there are certain fixed stars known to 
astronomers under the name of variable , on account of changes 
taking place in their appearance as seen from the earth. These 
stars being in regions of space far beyond our planetary system, any 
change in them, I presume, can have little or no influence on our 
system. But it' might be greatly more serious for us were im- 
portant changes to occur in our sun, the centre of our system ; — 
and these changes would no doubt be at once detected by means 
of the spectroscope* and the comprehensive diagrams which Pro- 
fessor Piazzi Smyth has constructed of the solar spectrum, as it 
now exists. 
Having offered these explanations, which, however, I have done 
with the utmost diffidence both as regards this subject generally, 
and the merits of the paper before us, it only remains for me to 
deliver the prize into the hands of the distinguished author ; and 
at the same time to offer to him my humble, respectful, but very 
