IIt 
The spectroscopic analysis of its light was very important. On 
the 14th July, with the kind assistanee of Dr. Prince, he attached his 
automatic spectroscope to that gentleman’s telescope, and was enabled 
to see the spectrum of the different portions of the comet near the 
nucleus, and to measure the position of the bands observed. The 
tail exhibited a faint continuous spectrum as a background, with two 
bright lines, or rather diffused bands, lying across it, each of them 
fading off more abruptly on the red side. ‘He might have overlooked 
a third and fainter one, which had been seen by Dr. Huggins, but 
not by Mr. Christie, first assistant at Greenwich Observatory. Imme- 
diately noting the readings of the micrometer of his spectroscope for 
the position of the bands he had observed, he waited with some im- 
patience to compare them with measures of lines of some of the 
elements. Several months previously, he had entered in his note- 
book measures of all the lines visible in the flame spectrum of carbon, 
and he now found two of these lines coincide with the brightest parts 
of the two bands of the comet’s spectrum. The lines were situated, 
the one in the olive group half-way between D and E; the other in 
the green group between E and F, and both occupied the second place 
in their respective groups, reckoning from the redend. This would 
give a high probability that the lines in the spectrum of the comet were 
due to the presence of carbon in the state of vapour, in agreement with 
the announcements of Messrs. Huggins, Secchi, and Christie. But it 
was important to keep in mind that greater certainty in the matter 
would be attainable could the comet’s spectrum of bands be reduced 
to one of lines. Hitherto no one had announced that he had been 
able to do this. The spectrum of the coma was similar to that of the 
tail. The sector and the envelope gave spectra of a different order, 
being continuous, and suggesting the presence of incandescent solids, 
‘or the reflection of light from such. 
The most conspicuous part of the comet’s spectruny was that of 
the nucleus, which was bright and continuous, giving, as far as he 
could observe, no bright lines or bands. He saw it fade off gradually, 
but completely, before reaching the blue rays, and that at the red end 
there was a sudden diminution of its brightness, after which it could 
be traced for some distance, as if the red end was crossed by absorp- 
tion bands, and that the light was too much weakened to render them 
clearly visible as bands. He placed the micrometer on the sudden 
beginning of the partially-absorbed rays, and at once saw it was close 
